[1/2] Bluetooth: Add support for devcoredump

From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

Add devcoredump APIs to hci core so that drivers only have to provide
the dump skbs instead of managing the synchronization and timeouts.

The devcoredump APIs should be used in the following manner:
 - hci_devcoredump_init is called to allocate the dump.
 - hci_devcoredump_append is called to append any skbs with dump data
   OR hci_devcoredump_append_pattern is called to insert a pattern.
 - hci_devcoredump_complete is called when all dump packets have been
   sent OR hci_devcoredump_abort is called to indicate an error and
   cancel an ongoing dump collection.

The high level APIs just prepare some skbs with the appropriate data and
queue it for the dump to process. Packets part of the crashdump can be
intercepted in the driver in interrupt context and forwarded directly to
the devcoredump APIs.

Internally, there are 5 states for the dump: idle, active, complete,
abort and timeout. A devcoredump will only be in active state after it
has been initialized. Once active, it accepts data to be appended,
patterns to be inserted (i.e. memset) and a completion event or an abort
event to generate a devcoredump. The timeout is initialized at the same
time the dump is initialized (defaulting to 10s) and will be cleared
either when the timeout occurs or the dump is complete or aborted.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
---

 include/net/bluetooth/hci_core.h |  51 ++++
 net/bluetooth/hci_core.c         | 496 +++++++++++++++++++++++++++++++
 net/bluetooth/hci_sync.c         |   2 +
 3 files changed, 549 insertions(+)

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=624997

---Test result---

Test Summary:
CheckPatch                    FAIL      1.78 seconds
GitLint                       PASS      0.89 seconds
SubjectPrefix                 PASS      0.64 seconds
BuildKernel                   PASS      38.17 seconds
BuildKernel32                 PASS      33.98 seconds
Incremental Build with patchesPASS      53.60 seconds
TestRunner: Setup             PASS      594.46 seconds
TestRunner: l2cap-tester      PASS      18.39 seconds
TestRunner: bnep-tester       PASS      7.43 seconds
TestRunner: mgmt-tester       PASS      125.35 seconds
TestRunner: rfcomm-tester     PASS      9.63 seconds
TestRunner: sco-tester        PASS      9.35 seconds
TestRunner: smp-tester        PASS      9.48 seconds
TestRunner: userchan-tester   PASS      7.82 seconds

Details
##############################
Test: CheckPatch - FAIL - 1.78 seconds
Run checkpatch.pl script with rule in .checkpatch.conf
[1/2] Bluetooth: Add support for devcoredump\WARNING:SPLIT_STRING: quoted string split across lines
#498: FILE: net/bluetooth/hci_core.c:2696:
+				    "Devcoredump complete with size %u "
+				    "(expect %u)",

WARNING:SPLIT_STRING: quoted string split across lines
#517: FILE: net/bluetooth/hci_core.c:2715:
+				    "Devcoredump aborted with size %u "
+				    "(expect %u)",

WARNING:OOM_MESSAGE: Possible unnecessary 'out of memory' message
#598: FILE: net/bluetooth/hci_core.c:2796:
+	if (!skb) {
+		bt_dev_err(hdev, "Failed to allocate devcoredump init");

WARNING:OOM_MESSAGE: Possible unnecessary 'out of memory' message
#641: FILE: net/bluetooth/hci_core.c:2839:
+	if (!skb) {
+		bt_dev_err(hdev, "Failed to allocate devcoredump pattern");

WARNING:OOM_MESSAGE: Possible unnecessary 'out of memory' message
#667: FILE: net/bluetooth/hci_core.c:2865:
+	if (!skb) {
+		bt_dev_err(hdev, "Failed to allocate devcoredump complete");

WARNING:OOM_MESSAGE: Possible unnecessary 'out of memory' message
#689: FILE: net/bluetooth/hci_core.c:2887:
+	if (!skb) {
+		bt_dev_err(hdev, "Failed to allocate devcoredump abort");

total: 0 errors, 6 warnings, 0 checks, 599 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

/github/workspace/src/12786731.patch has style problems, please review.

NOTE: Ignored message types: UNKNOWN_COMMIT_ID

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.




---
Regards,
Linux Bluetooth

Hi Manish,

On Sun, Mar 20, 2022 at 6:34 PM Manish Mandlik <mmandlik@google.com> wrote:
>
> From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>
> Add devcoredump APIs to hci core so that drivers only have to provide
> the dump skbs instead of managing the synchronization and timeouts.
>
> The devcoredump APIs should be used in the following manner:
>  - hci_devcoredump_init is called to allocate the dump.
>  - hci_devcoredump_append is called to append any skbs with dump data
>    OR hci_devcoredump_append_pattern is called to insert a pattern.
>  - hci_devcoredump_complete is called when all dump packets have been
>    sent OR hci_devcoredump_abort is called to indicate an error and
>    cancel an ongoing dump collection.
>
> The high level APIs just prepare some skbs with the appropriate data and
> queue it for the dump to process. Packets part of the crashdump can be
> intercepted in the driver in interrupt context and forwarded directly to
> the devcoredump APIs.

If this sort of information comes from telemetry support it can be
intercepted by other means as well e.g. btmon, in fact I think that
would have been better since we already dump the backtrace of
bluetoothd crashes into the monitor as well. Anyway the kernel
devcoredump support seems to just be dumping the data into sysfs so we
could be fetching that information from there as well but I'm not
really sure what we would be gaining with that since we are just
adding yet another kernel dependency for something that userspace
could already be doing by itself.

> Internally, there are 5 states for the dump: idle, active, complete,
> abort and timeout. A devcoredump will only be in active state after it
> has been initialized. Once active, it accepts data to be appended,
> patterns to be inserted (i.e. memset) and a completion event or an abort
> event to generate a devcoredump. The timeout is initialized at the same
> time the dump is initialized (defaulting to 10s) and will be cleared
> either when the timeout occurs or the dump is complete or aborted.

Is there some userspace component parsing these dumps? Or we will need
to add some support for the likes of btmon to collect the logs from
sysfs?

> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Manish Mandlik <mmandlik@google.com>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> ---
>
>  include/net/bluetooth/hci_core.h |  51 ++++
>  net/bluetooth/hci_core.c         | 496 +++++++++++++++++++++++++++++++
>  net/bluetooth/hci_sync.c         |   2 +
>  3 files changed, 549 insertions(+)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index d5377740e99c..818ba3a43e8c 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -118,6 +118,43 @@ enum suspended_state {
>         BT_SUSPEND_CONFIGURE_WAKE,
>  };
>
> +#define DEVCOREDUMP_TIMEOUT    msecs_to_jiffies(100000)        /* 100 sec */
> +
> +typedef int  (*dmp_hdr_t)(struct hci_dev *hdev, char *buf, size_t size);
> +typedef void (*notify_change_t)(struct hci_dev *hdev, int state);
> +
> +/* struct hci_devcoredump - Devcoredump state
> + *
> + * @supported: Indicates if FW dump collection is supported by driver
> + * @state: Current state of dump collection
> + * @alloc_size: Total size of the dump
> + * @head: Start of the dump
> + * @tail: Pointer to current end of dump
> + * @end: head + alloc_size for easy comparisons
> + *
> + * @dmp_hdr: Create a dump header to identify controller/fw/driver info
> + * @notify_change: Notify driver when devcoredump state has changed
> + */
> +struct hci_devcoredump {
> +       bool            supported;
> +
> +       enum devcoredump_state {
> +               HCI_DEVCOREDUMP_IDLE,
> +               HCI_DEVCOREDUMP_ACTIVE,
> +               HCI_DEVCOREDUMP_DONE,
> +               HCI_DEVCOREDUMP_ABORT,
> +               HCI_DEVCOREDUMP_TIMEOUT
> +       } state;
> +
> +       u32             alloc_size;
> +       char            *head;
> +       char            *tail;
> +       char            *end;
> +
> +       dmp_hdr_t       dmp_hdr;
> +       notify_change_t notify_change;
> +};
> +
>  struct hci_conn_hash {
>         struct list_head list;
>         unsigned int     acl_num;
> @@ -568,6 +605,11 @@ struct hci_dev {
>         const char              *fw_info;
>         struct dentry           *debugfs;
>
> +       struct hci_devcoredump  dump;
> +       struct sk_buff_head     dump_q;
> +       struct work_struct      dump_rx;
> +       struct delayed_work     dump_timeout;
> +
>         struct device           dev;
>
>         struct rfkill           *rfkill;
> @@ -1308,6 +1350,15 @@ static inline void hci_set_aosp_capable(struct hci_dev *hdev)
>  #endif
>  }
>
> +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
> +                            notify_change_t notify_change);
> +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size);
> +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb);
> +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len);
> +int hci_devcoredump_complete(struct hci_dev *hdev);
> +int hci_devcoredump_abort(struct hci_dev *hdev);
> +void hci_devcoredump_reset(struct hci_dev *hdev);
> +
>  int hci_dev_open(__u16 dev);
>  int hci_dev_close(__u16 dev);
>  int hci_dev_do_close(struct hci_dev *hdev);
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index b4782a6c1025..76dbb6b28870 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -28,6 +28,7 @@
>  #include <linux/export.h>
>  #include <linux/rfkill.h>
>  #include <linux/debugfs.h>
> +#include <linux/devcoredump.h>
>  #include <linux/crypto.h>
>  #include <linux/property.h>
>  #include <linux/suspend.h>
> @@ -2404,6 +2405,498 @@ static int hci_suspend_notifier(struct notifier_block *nb, unsigned long action,
>         return NOTIFY_DONE;
>  }
>
> +enum hci_devcoredump_pkt_type {
> +       HCI_DEVCOREDUMP_PKT_INIT,
> +       HCI_DEVCOREDUMP_PKT_SKB,
> +       HCI_DEVCOREDUMP_PKT_PATTERN,
> +       HCI_DEVCOREDUMP_PKT_COMPLETE,
> +       HCI_DEVCOREDUMP_PKT_ABORT,
> +};
> +
> +struct hci_devcoredump_skb_cb {
> +       u16 pkt_type;
> +};
> +
> +struct hci_devcoredump_skb_pattern {
> +       u8 pattern;
> +       u32 len;
> +} __packed;
> +
> +#define hci_dmp_cb(skb)        ((struct hci_devcoredump_skb_cb *)((skb)->cb))
> +
> +#define MAX_DEVCOREDUMP_HDR_SIZE       512     /* bytes */
> +
> +static int hci_devcoredump_update_hdr_state(char *buf, size_t size, int state)
> +{
> +       if (!buf)
> +               return 0;
> +
> +       return snprintf(buf, size, "Bluetooth devcoredump\nState: %d\n", state);
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static int hci_devcoredump_update_state(struct hci_dev *hdev, int state)
> +{
> +       hdev->dump.state = state;
> +
> +       return hci_devcoredump_update_hdr_state(hdev->dump.head,
> +                                               hdev->dump.alloc_size, state);
> +}
> +
> +static int hci_devcoredump_mkheader(struct hci_dev *hdev, char *buf,
> +                                   size_t buf_size)
> +{
> +       char *ptr = buf;
> +       size_t rem = buf_size;
> +       size_t read = 0;
> +
> +       read = hci_devcoredump_update_hdr_state(ptr, rem, HCI_DEVCOREDUMP_IDLE);
> +       read += 1; /* update_hdr_state adds \0 at the end upon state rewrite */
> +       rem -= read;
> +       ptr += read;
> +
> +       if (hdev->dump.dmp_hdr) {
> +               /* dmp_hdr() should return number of bytes written */
> +               read = hdev->dump.dmp_hdr(hdev, ptr, rem);
> +               rem -= read;
> +               ptr += read;
> +       }
> +
> +       read = snprintf(ptr, rem, "--- Start dump ---\n");
> +       rem -= read;
> +       ptr += read;
> +
> +       return buf_size - rem;
> +}
> +
> +/* Do not call with hci_dev_lock since this calls driver code. */
> +static void hci_devcoredump_notify(struct hci_dev *hdev, int state)
> +{
> +       if (hdev->dump.notify_change)
> +               hdev->dump.notify_change(hdev, state);
> +}
> +
> +/* Call with hci_dev_lock only. */
> +void hci_devcoredump_reset(struct hci_dev *hdev)
> +{
> +       hdev->dump.head = NULL;
> +       hdev->dump.tail = NULL;
> +       hdev->dump.alloc_size = 0;
> +
> +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
> +
> +       cancel_delayed_work(&hdev->dump_timeout);
> +       skb_queue_purge(&hdev->dump_q);
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static void hci_devcoredump_free(struct hci_dev *hdev)
> +{
> +       if (hdev->dump.head)
> +               vfree(hdev->dump.head);
> +
> +       hci_devcoredump_reset(hdev);
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static int hci_devcoredump_alloc(struct hci_dev *hdev, u32 size)
> +{
> +       hdev->dump.head = vmalloc(size);
> +       if (!hdev->dump.head)
> +               return -ENOMEM;
> +
> +       hdev->dump.alloc_size = size;
> +       hdev->dump.tail = hdev->dump.head;
> +       hdev->dump.end = hdev->dump.head + size;
> +
> +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
> +
> +       return 0;
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static bool hci_devcoredump_copy(struct hci_dev *hdev, char *buf, u32 size)
> +{
> +       if (hdev->dump.tail + size > hdev->dump.end)
> +               return false;
> +
> +       memcpy(hdev->dump.tail, buf, size);
> +       hdev->dump.tail += size;
> +
> +       return true;
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static bool hci_devcoredump_memset(struct hci_dev *hdev, u8 pattern, u32 len)
> +{
> +       if (hdev->dump.tail + len > hdev->dump.end)
> +               return false;
> +
> +       memset(hdev->dump.tail, pattern, len);
> +       hdev->dump.tail += len;
> +
> +       return true;
> +}
> +
> +/* Call with hci_dev_lock only. */
> +static int hci_devcoredump_prepare(struct hci_dev *hdev, u32 dump_size)
> +{
> +       char *dump_hdr;
> +       int dump_hdr_size;
> +       u32 size;
> +       int err = 0;
> +
> +       dump_hdr = vmalloc(MAX_DEVCOREDUMP_HDR_SIZE);
> +       if (!dump_hdr) {
> +               err = -ENOMEM;
> +               goto hdr_free;
> +       }
> +
> +       dump_hdr_size = hci_devcoredump_mkheader(hdev, dump_hdr,
> +                                                MAX_DEVCOREDUMP_HDR_SIZE);
> +       size = dump_hdr_size + dump_size;
> +
> +       if (hci_devcoredump_alloc(hdev, size)) {
> +               err = -ENOMEM;
> +               goto hdr_free;
> +       }
> +
> +       /* Insert the device header */
> +       if (!hci_devcoredump_copy(hdev, dump_hdr, dump_hdr_size)) {
> +               bt_dev_err(hdev, "Failed to insert header");
> +               hci_devcoredump_free(hdev);
> +
> +               err = -ENOMEM;
> +               goto hdr_free;
> +       }
> +
> +hdr_free:
> +       if (dump_hdr)
> +               vfree(dump_hdr);
> +
> +       return err;
> +}
> +
> +/* Bluetooth devcoredump state machine.
> + *
> + * Devcoredump states:
> + *
> + *      HCI_DEVCOREDUMP_IDLE: The default state.
> + *
> + *      HCI_DEVCOREDUMP_ACTIVE: A devcoredump will be in this state once it has
> + *              been initialized using hci_devcoredump_init(). Once active, the
> + *              driver can append data using hci_devcoredump_append() or insert
> + *              a pattern using hci_devcoredump_append_pattern().
> + *
> + *      HCI_DEVCOREDUMP_DONE: Once the dump collection is complete, the drive
> + *              can signal the completion using hci_devcoredump_complete(). A
> + *              devcoredump is generated indicating the completion event and
> + *              then the state machine is reset to the default state.
> + *
> + *      HCI_DEVCOREDUMP_ABORT: The driver can cancel ongoing dump collection in
> + *              case of any error using hci_devcoredump_abort(). A devcoredump
> + *              is still generated with the available data indicating the abort
> + *              event and then the state machine is reset to the default state.
> + *
> + *      HCI_DEVCOREDUMP_TIMEOUT: A timeout timer for HCI_DEVCOREDUMP_TIMEOUT sec
> + *              is started during devcoredump initialization. Once the timeout
> + *              occurs, the driver is notified, a devcoredump is generated with
> + *              the available data indicating the timeout event and then the
> + *              state machine is reset to the default state.
> + *
> + * The driver must register using hci_devcoredump_register() before using the
> + * hci devcoredump APIs.
> + */
> +static void hci_devcoredump_rx(struct work_struct *work)
> +{
> +       struct hci_dev *hdev = container_of(work, struct hci_dev, dump_rx);
> +       struct sk_buff *skb;
> +       struct hci_devcoredump_skb_pattern *pattern;
> +       u32 dump_size;
> +       int start_state;
> +
> +#define DBG_UNEXPECTED_STATE() \
> +               bt_dev_dbg(hdev, \
> +                          "Unexpected packet (%d) for state (%d). ", \
> +                          hci_dmp_cb(skb)->pkt_type, hdev->dump.state)
> +
> +       while ((skb = skb_dequeue(&hdev->dump_q))) {
> +               hci_dev_lock(hdev);
> +               start_state = hdev->dump.state;
> +
> +               switch (hci_dmp_cb(skb)->pkt_type) {
> +               case HCI_DEVCOREDUMP_PKT_INIT:
> +                       if (hdev->dump.state != HCI_DEVCOREDUMP_IDLE) {
> +                               DBG_UNEXPECTED_STATE();
> +                               goto loop_continue;
> +                       }
> +
> +                       if (skb->len != sizeof(dump_size)) {
> +                               bt_dev_dbg(hdev, "Invalid dump init pkt");
> +                               goto loop_continue;
> +                       }
> +
> +                       dump_size = *((u32 *)skb->data);
> +                       if (!dump_size) {
> +                               bt_dev_err(hdev, "Zero size dump init pkt");
> +                               goto loop_continue;
> +                       }
> +
> +                       if (hci_devcoredump_prepare(hdev, dump_size)) {
> +                               bt_dev_err(hdev, "Failed to prepare for dump");
> +                               goto loop_continue;
> +                       }
> +
> +                       hci_devcoredump_update_state(hdev,
> +                                                    HCI_DEVCOREDUMP_ACTIVE);
> +                       queue_delayed_work(hdev->workqueue, &hdev->dump_timeout,
> +                                          DEVCOREDUMP_TIMEOUT);
> +                       break;
> +
> +               case HCI_DEVCOREDUMP_PKT_SKB:
> +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
> +                               DBG_UNEXPECTED_STATE();
> +                               goto loop_continue;
> +                       }
> +
> +                       if (!hci_devcoredump_copy(hdev, skb->data, skb->len))
> +                               bt_dev_dbg(hdev, "Failed to insert skb");
> +                       break;
> +
> +               case HCI_DEVCOREDUMP_PKT_PATTERN:
> +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
> +                               DBG_UNEXPECTED_STATE();
> +                               goto loop_continue;
> +                       }
> +
> +                       if (skb->len != sizeof(*pattern)) {
> +                               bt_dev_dbg(hdev, "Invalid pattern skb");
> +                               goto loop_continue;
> +                       }
> +
> +                       pattern = (void *)skb->data;
> +
> +                       if (!hci_devcoredump_memset(hdev, pattern->pattern,
> +                                                   pattern->len))
> +                               bt_dev_dbg(hdev, "Failed to set pattern");
> +                       break;
> +
> +               case HCI_DEVCOREDUMP_PKT_COMPLETE:
> +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
> +                               DBG_UNEXPECTED_STATE();
> +                               goto loop_continue;
> +                       }
> +
> +                       hci_devcoredump_update_state(hdev,
> +                                                    HCI_DEVCOREDUMP_DONE);
> +                       dump_size = hdev->dump.tail - hdev->dump.head;
> +
> +                       bt_dev_info(hdev,
> +                                   "Devcoredump complete with size %u "
> +                                   "(expect %u)",
> +                                   dump_size, hdev->dump.alloc_size);
> +
> +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
> +                                     GFP_KERNEL);
> +                       break;
> +
> +               case HCI_DEVCOREDUMP_PKT_ABORT:
> +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
> +                               DBG_UNEXPECTED_STATE();
> +                               goto loop_continue;
> +                       }
> +
> +                       hci_devcoredump_update_state(hdev,
> +                                                    HCI_DEVCOREDUMP_ABORT);
> +                       dump_size = hdev->dump.tail - hdev->dump.head;
> +
> +                       bt_dev_info(hdev,
> +                                   "Devcoredump aborted with size %u "
> +                                   "(expect %u)",
> +                                   dump_size, hdev->dump.alloc_size);
> +
> +                       /* Emit a devcoredump with the available data */
> +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
> +                                     GFP_KERNEL);
> +                       break;
> +
> +               default:
> +                       bt_dev_dbg(hdev,
> +                                  "Unknown packet (%d) for state (%d). ",
> +                                  hci_dmp_cb(skb)->pkt_type, hdev->dump.state);
> +                       break;
> +               }
> +
> +loop_continue:
> +               kfree_skb(skb);
> +               hci_dev_unlock(hdev);
> +
> +               if (start_state != hdev->dump.state)
> +                       hci_devcoredump_notify(hdev, hdev->dump.state);
> +
> +               hci_dev_lock(hdev);
> +               if (hdev->dump.state == HCI_DEVCOREDUMP_DONE ||
> +                   hdev->dump.state == HCI_DEVCOREDUMP_ABORT)
> +                       hci_devcoredump_reset(hdev);
> +               hci_dev_unlock(hdev);
> +       }
> +}
> +
> +static void hci_devcoredump_timeout(struct work_struct *work)
> +{
> +       struct hci_dev *hdev = container_of(work, struct hci_dev,
> +                                           dump_timeout.work);
> +       u32 dump_size;
> +
> +       hci_devcoredump_notify(hdev, HCI_DEVCOREDUMP_TIMEOUT);
> +
> +       hci_dev_lock(hdev);
> +
> +       cancel_work_sync(&hdev->dump_rx);
> +
> +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_TIMEOUT);
> +       dump_size = hdev->dump.tail - hdev->dump.head;
> +       bt_dev_info(hdev, "Devcoredump timeout with size %u (expect %u)",
> +                   dump_size, hdev->dump.alloc_size);
> +
> +       /* Emit a devcoredump with the available data */
> +       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
> +
> +       hci_devcoredump_reset(hdev);
> +
> +       hci_dev_unlock(hdev);
> +}
> +
> +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
> +                            notify_change_t notify_change)
> +{
> +       /* driver must implement dmp_hdr() function for bluetooth devcoredump */
> +       if (!dmp_hdr)
> +               return -EINVAL;
> +
> +       hci_dev_lock(hdev);
> +       hdev->dump.dmp_hdr = dmp_hdr;
> +       hdev->dump.notify_change = notify_change;
> +       hdev->dump.supported = true;
> +       hci_dev_unlock(hdev);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_register);
> +
> +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size)
> +{
> +       struct sk_buff *skb = NULL;
> +
> +       if (!hdev->dump.supported)
> +               return -EOPNOTSUPP;
> +
> +       skb = alloc_skb(sizeof(dmp_size), GFP_ATOMIC);
> +       if (!skb) {
> +               bt_dev_err(hdev, "Failed to allocate devcoredump init");
> +               return -ENOMEM;
> +       }
> +
> +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_INIT;
> +       skb_put_data(skb, &dmp_size, sizeof(dmp_size));
> +
> +       skb_queue_tail(&hdev->dump_q, skb);
> +       queue_work(hdev->workqueue, &hdev->dump_rx);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_init);
> +
> +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb)
> +{
> +       if (!skb)
> +               return -ENOMEM;
> +
> +       if (!hdev->dump.supported) {
> +               kfree_skb(skb);
> +               return -EOPNOTSUPP;
> +       }
> +
> +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_SKB;
> +
> +       skb_queue_tail(&hdev->dump_q, skb);
> +       queue_work(hdev->workqueue, &hdev->dump_rx);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_append);
> +
> +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len)
> +{
> +       struct hci_devcoredump_skb_pattern p;
> +       struct sk_buff *skb = NULL;
> +
> +       if (!hdev->dump.supported)
> +               return -EOPNOTSUPP;
> +
> +       skb = alloc_skb(sizeof(p), GFP_ATOMIC);
> +       if (!skb) {
> +               bt_dev_err(hdev, "Failed to allocate devcoredump pattern");
> +               return -ENOMEM;
> +       }
> +
> +       p.pattern = pattern;
> +       p.len = len;
> +
> +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_PATTERN;
> +       skb_put_data(skb, &p, sizeof(p));
> +
> +       skb_queue_tail(&hdev->dump_q, skb);
> +       queue_work(hdev->workqueue, &hdev->dump_rx);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_append_pattern);
> +
> +int hci_devcoredump_complete(struct hci_dev *hdev)
> +{
> +       struct sk_buff *skb = NULL;
> +
> +       if (!hdev->dump.supported)
> +               return -EOPNOTSUPP;
> +
> +       skb = alloc_skb(0, GFP_ATOMIC);
> +       if (!skb) {
> +               bt_dev_err(hdev, "Failed to allocate devcoredump complete");
> +               return -ENOMEM;
> +       }
> +
> +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_COMPLETE;
> +
> +       skb_queue_tail(&hdev->dump_q, skb);
> +       queue_work(hdev->workqueue, &hdev->dump_rx);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_complete);
> +
> +int hci_devcoredump_abort(struct hci_dev *hdev)
> +{
> +       struct sk_buff *skb = NULL;
> +
> +       if (!hdev->dump.supported)
> +               return -EOPNOTSUPP;
> +
> +       skb = alloc_skb(0, GFP_ATOMIC);
> +       if (!skb) {
> +               bt_dev_err(hdev, "Failed to allocate devcoredump abort");
> +               return -ENOMEM;
> +       }
> +
> +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_ABORT;
> +
> +       skb_queue_tail(&hdev->dump_q, skb);
> +       queue_work(hdev->workqueue, &hdev->dump_rx);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(hci_devcoredump_abort);
> +
>  /* Alloc HCI device */
>  struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>  {
> @@ -2511,14 +3004,17 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>         INIT_WORK(&hdev->tx_work, hci_tx_work);
>         INIT_WORK(&hdev->power_on, hci_power_on);
>         INIT_WORK(&hdev->error_reset, hci_error_reset);
> +       INIT_WORK(&hdev->dump_rx, hci_devcoredump_rx);
>
>         hci_cmd_sync_init(hdev);
>
>         INIT_DELAYED_WORK(&hdev->power_off, hci_power_off);
> +       INIT_DELAYED_WORK(&hdev->dump_timeout, hci_devcoredump_timeout);
>
>         skb_queue_head_init(&hdev->rx_q);
>         skb_queue_head_init(&hdev->cmd_q);
>         skb_queue_head_init(&hdev->raw_q);
> +       skb_queue_head_init(&hdev->dump_q);
>
>         init_waitqueue_head(&hdev->req_wait_q);
>
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index 8f4c5698913d..ec03fa871ef0 100644
> --- a/net/bluetooth/hci_sync.c
> +++ b/net/bluetooth/hci_sync.c
> @@ -3877,6 +3877,8 @@ int hci_dev_open_sync(struct hci_dev *hdev)
>                 goto done;
>         }
>
> +       hci_devcoredump_reset(hdev);
> +
>         set_bit(HCI_RUNNING, &hdev->flags);
>         hci_sock_dev_event(hdev, HCI_DEV_OPEN);
>
> --
> 2.35.1.894.gb6a874cedc-goog
>

Hi Manish,

On Tue, May 3, 2022 at 4:00 PM Manish Mandlik <mmandlik@google.com> wrote:
>
> Hi Luiz,
>
> On Mon, Mar 21, 2022 at 9:46 AM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>>
>> Hi Manish,
>>
>> On Sun, Mar 20, 2022 at 6:34 PM Manish Mandlik <mmandlik@google.com> wrote:
>> >
>> > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> >
>> > Add devcoredump APIs to hci core so that drivers only have to provide
>> > the dump skbs instead of managing the synchronization and timeouts.
>> >
>> > The devcoredump APIs should be used in the following manner:
>> >  - hci_devcoredump_init is called to allocate the dump.
>> >  - hci_devcoredump_append is called to append any skbs with dump data
>> >    OR hci_devcoredump_append_pattern is called to insert a pattern.
>> >  - hci_devcoredump_complete is called when all dump packets have been
>> >    sent OR hci_devcoredump_abort is called to indicate an error and
>> >    cancel an ongoing dump collection.
>> >
>> > The high level APIs just prepare some skbs with the appropriate data and
>> > queue it for the dump to process. Packets part of the crashdump can be
>> > intercepted in the driver in interrupt context and forwarded directly to
>> > the devcoredump APIs.
>>
>> If this sort of information comes from telemetry support it can be
>> intercepted by other means as well e.g. btmon, in fact I think that
>> would have been better since we already dump the backtrace of
>> bluetoothd crashes into the monitor as well. Anyway the kernel
>> devcoredump support seems to just be dumping the data into sysfs so we
>> could be fetching that information from there as well but I'm not
>> really sure what we would be gaining with that since we are just
>> adding yet another kernel dependency for something that userspace
>> could already be doing by itself.
>
> Currently every vendor has their own way of collecting firmware dumps. The main intention of adding devcoredump support for bluetooth is to provide a unified way to collect firmware crashdumps across all vendors/controllers. This will generate a dump file in the sysfs and vendors can use it for further debugging. There is no plan to include any information from these dumps into the btmon logs.
>
>>
>> > Internally, there are 5 states for the dump: idle, active, complete,
>> > abort and timeout. A devcoredump will only be in active state after it
>> > has been initialized. Once active, it accepts data to be appended,
>> > patterns to be inserted (i.e. memset) and a completion event or an abort
>> > event to generate a devcoredump. The timeout is initialized at the same
>> > time the dump is initialized (defaulting to 10s) and will be cleared
>> > either when the timeout occurs or the dump is complete or aborted.
>>
>> Is there some userspace component parsing these dumps? Or we will need
>> to add some support for the likes of btmon to collect the logs from
>> sysfs?
>
> Yes, user space component is required to parse these dumps. But these tools will be vendor specific and could be proprietary. However, ChromeOS would be using these dumps to identify bluetooth firmware crashes. I'll share more information on ChromeOS use case offline.

Fair enough, but we do need some way to exercise this code by the CI,
so at very least we need emulator support otherwise it needs to be
behind an experimental UUID until proper tests are introduced.

>>
>>
>> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> > Signed-off-by: Manish Mandlik <mmandlik@google.com>
>> > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> > ---
>> >
>> >  include/net/bluetooth/hci_core.h |  51 ++++
>> >  net/bluetooth/hci_core.c         | 496 +++++++++++++++++++++++++++++++
>> >  net/bluetooth/hci_sync.c         |   2 +
>> >  3 files changed, 549 insertions(+)
>> >
>> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
>> > index d5377740e99c..818ba3a43e8c 100644
>> > --- a/include/net/bluetooth/hci_core.h
>> > +++ b/include/net/bluetooth/hci_core.h
>> > @@ -118,6 +118,43 @@ enum suspended_state {
>> >         BT_SUSPEND_CONFIGURE_WAKE,
>> >  };
>> >
>> > +#define DEVCOREDUMP_TIMEOUT    msecs_to_jiffies(100000)        /* 100 sec */
>> > +
>> > +typedef int  (*dmp_hdr_t)(struct hci_dev *hdev, char *buf, size_t size);
>> > +typedef void (*notify_change_t)(struct hci_dev *hdev, int state);
>> > +
>> > +/* struct hci_devcoredump - Devcoredump state
>> > + *
>> > + * @supported: Indicates if FW dump collection is supported by driver
>> > + * @state: Current state of dump collection
>> > + * @alloc_size: Total size of the dump
>> > + * @head: Start of the dump
>> > + * @tail: Pointer to current end of dump
>> > + * @end: head + alloc_size for easy comparisons
>> > + *
>> > + * @dmp_hdr: Create a dump header to identify controller/fw/driver info
>> > + * @notify_change: Notify driver when devcoredump state has changed
>> > + */
>> > +struct hci_devcoredump {
>> > +       bool            supported;
>> > +
>> > +       enum devcoredump_state {
>> > +               HCI_DEVCOREDUMP_IDLE,
>> > +               HCI_DEVCOREDUMP_ACTIVE,
>> > +               HCI_DEVCOREDUMP_DONE,
>> > +               HCI_DEVCOREDUMP_ABORT,
>> > +               HCI_DEVCOREDUMP_TIMEOUT
>> > +       } state;
>> > +
>> > +       u32             alloc_size;
>> > +       char            *head;
>> > +       char            *tail;
>> > +       char            *end;
>> > +
>> > +       dmp_hdr_t       dmp_hdr;
>> > +       notify_change_t notify_change;
>> > +};
>> > +
>> >  struct hci_conn_hash {
>> >         struct list_head list;
>> >         unsigned int     acl_num;
>> > @@ -568,6 +605,11 @@ struct hci_dev {
>> >         const char              *fw_info;
>> >         struct dentry           *debugfs;
>> >
>> > +       struct hci_devcoredump  dump;
>> > +       struct sk_buff_head     dump_q;
>> > +       struct work_struct      dump_rx;
>> > +       struct delayed_work     dump_timeout;
>> > +
>> >         struct device           dev;
>> >
>> >         struct rfkill           *rfkill;
>> > @@ -1308,6 +1350,15 @@ static inline void hci_set_aosp_capable(struct hci_dev *hdev)
>> >  #endif
>> >  }
>> >
>> > +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
>> > +                            notify_change_t notify_change);
>> > +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size);
>> > +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb);
>> > +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len);
>> > +int hci_devcoredump_complete(struct hci_dev *hdev);
>> > +int hci_devcoredump_abort(struct hci_dev *hdev);
>> > +void hci_devcoredump_reset(struct hci_dev *hdev);
>> > +
>> >  int hci_dev_open(__u16 dev);
>> >  int hci_dev_close(__u16 dev);
>> >  int hci_dev_do_close(struct hci_dev *hdev);
>> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
>> > index b4782a6c1025..76dbb6b28870 100644
>> > --- a/net/bluetooth/hci_core.c
>> > +++ b/net/bluetooth/hci_core.c
>> > @@ -28,6 +28,7 @@
>> >  #include <linux/export.h>
>> >  #include <linux/rfkill.h>
>> >  #include <linux/debugfs.h>
>> > +#include <linux/devcoredump.h>
>> >  #include <linux/crypto.h>
>> >  #include <linux/property.h>
>> >  #include <linux/suspend.h>
>> > @@ -2404,6 +2405,498 @@ static int hci_suspend_notifier(struct notifier_block *nb, unsigned long action,
>> >         return NOTIFY_DONE;
>> >  }
>> >
>> > +enum hci_devcoredump_pkt_type {
>> > +       HCI_DEVCOREDUMP_PKT_INIT,
>> > +       HCI_DEVCOREDUMP_PKT_SKB,
>> > +       HCI_DEVCOREDUMP_PKT_PATTERN,
>> > +       HCI_DEVCOREDUMP_PKT_COMPLETE,
>> > +       HCI_DEVCOREDUMP_PKT_ABORT,
>> > +};

I'd move the documentation of the states here, also perhaps we should
have the handling of devcoredump in its own file e.g. coredump.c,
since hci_core.c is quite big already adding things that are not part
of HCI/core specification makes it even bigger.

>> > +struct hci_devcoredump_skb_cb {
>> > +       u16 pkt_type;
>> > +};
>> > +
>> > +struct hci_devcoredump_skb_pattern {
>> > +       u8 pattern;
>> > +       u32 len;
>> > +} __packed;
>> > +
>> > +#define hci_dmp_cb(skb)        ((struct hci_devcoredump_skb_cb *)((skb)->cb))
>> > +
>> > +#define MAX_DEVCOREDUMP_HDR_SIZE       512     /* bytes */
>> > +
>> > +static int hci_devcoredump_update_hdr_state(char *buf, size_t size, int state)
>> > +{
>> > +       if (!buf)
>> > +               return 0;
>> > +
>> > +       return snprintf(buf, size, "Bluetooth devcoredump\nState: %d\n", state);
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static int hci_devcoredump_update_state(struct hci_dev *hdev, int state)
>> > +{
>> > +       hdev->dump.state = state;
>> > +
>> > +       return hci_devcoredump_update_hdr_state(hdev->dump.head,
>> > +                                               hdev->dump.alloc_size, state);
>> > +}
>> > +
>> > +static int hci_devcoredump_mkheader(struct hci_dev *hdev, char *buf,
>> > +                                   size_t buf_size)
>> > +{
>> > +       char *ptr = buf;
>> > +       size_t rem = buf_size;
>> > +       size_t read = 0;
>> > +
>> > +       read = hci_devcoredump_update_hdr_state(ptr, rem, HCI_DEVCOREDUMP_IDLE);
>> > +       read += 1; /* update_hdr_state adds \0 at the end upon state rewrite */
>> > +       rem -= read;
>> > +       ptr += read;
>> > +
>> > +       if (hdev->dump.dmp_hdr) {
>> > +               /* dmp_hdr() should return number of bytes written */
>> > +               read = hdev->dump.dmp_hdr(hdev, ptr, rem);
>> > +               rem -= read;
>> > +               ptr += read;
>> > +       }
>> > +
>> > +       read = snprintf(ptr, rem, "--- Start dump ---\n");
>> > +       rem -= read;
>> > +       ptr += read;
>> > +
>> > +       return buf_size - rem;
>> > +}
>> > +
>> > +/* Do not call with hci_dev_lock since this calls driver code. */
>> > +static void hci_devcoredump_notify(struct hci_dev *hdev, int state)
>> > +{
>> > +       if (hdev->dump.notify_change)
>> > +               hdev->dump.notify_change(hdev, state);
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +void hci_devcoredump_reset(struct hci_dev *hdev)
>> > +{
>> > +       hdev->dump.head = NULL;
>> > +       hdev->dump.tail = NULL;
>> > +       hdev->dump.alloc_size = 0;
>> > +
>> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
>> > +
>> > +       cancel_delayed_work(&hdev->dump_timeout);
>> > +       skb_queue_purge(&hdev->dump_q);
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static void hci_devcoredump_free(struct hci_dev *hdev)
>> > +{
>> > +       if (hdev->dump.head)
>> > +               vfree(hdev->dump.head);
>> > +
>> > +       hci_devcoredump_reset(hdev);
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static int hci_devcoredump_alloc(struct hci_dev *hdev, u32 size)
>> > +{
>> > +       hdev->dump.head = vmalloc(size);
>> > +       if (!hdev->dump.head)
>> > +               return -ENOMEM;
>> > +
>> > +       hdev->dump.alloc_size = size;
>> > +       hdev->dump.tail = hdev->dump.head;
>> > +       hdev->dump.end = hdev->dump.head + size;
>> > +
>> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
>> > +
>> > +       return 0;
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static bool hci_devcoredump_copy(struct hci_dev *hdev, char *buf, u32 size)
>> > +{
>> > +       if (hdev->dump.tail + size > hdev->dump.end)
>> > +               return false;
>> > +
>> > +       memcpy(hdev->dump.tail, buf, size);
>> > +       hdev->dump.tail += size;
>> > +
>> > +       return true;
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static bool hci_devcoredump_memset(struct hci_dev *hdev, u8 pattern, u32 len)
>> > +{
>> > +       if (hdev->dump.tail + len > hdev->dump.end)
>> > +               return false;
>> > +
>> > +       memset(hdev->dump.tail, pattern, len);
>> > +       hdev->dump.tail += len;
>> > +
>> > +       return true;
>> > +}
>> > +
>> > +/* Call with hci_dev_lock only. */
>> > +static int hci_devcoredump_prepare(struct hci_dev *hdev, u32 dump_size)
>> > +{
>> > +       char *dump_hdr;
>> > +       int dump_hdr_size;
>> > +       u32 size;
>> > +       int err = 0;
>> > +
>> > +       dump_hdr = vmalloc(MAX_DEVCOREDUMP_HDR_SIZE);
>> > +       if (!dump_hdr) {
>> > +               err = -ENOMEM;
>> > +               goto hdr_free;
>> > +       }
>> > +
>> > +       dump_hdr_size = hci_devcoredump_mkheader(hdev, dump_hdr,
>> > +                                                MAX_DEVCOREDUMP_HDR_SIZE);
>> > +       size = dump_hdr_size + dump_size;
>> > +
>> > +       if (hci_devcoredump_alloc(hdev, size)) {
>> > +               err = -ENOMEM;
>> > +               goto hdr_free;
>> > +       }
>> > +
>> > +       /* Insert the device header */
>> > +       if (!hci_devcoredump_copy(hdev, dump_hdr, dump_hdr_size)) {
>> > +               bt_dev_err(hdev, "Failed to insert header");
>> > +               hci_devcoredump_free(hdev);
>> > +
>> > +               err = -ENOMEM;
>> > +               goto hdr_free;
>> > +       }
>> > +
>> > +hdr_free:
>> > +       if (dump_hdr)
>> > +               vfree(dump_hdr);
>> > +
>> > +       return err;
>> > +}
>> > +
>> > +/* Bluetooth devcoredump state machine.
>> > + *
>> > + * Devcoredump states:
>> > + *
>> > + *      HCI_DEVCOREDUMP_IDLE: The default state.
>> > + *
>> > + *      HCI_DEVCOREDUMP_ACTIVE: A devcoredump will be in this state once it has
>> > + *              been initialized using hci_devcoredump_init(). Once active, the
>> > + *              driver can append data using hci_devcoredump_append() or insert
>> > + *              a pattern using hci_devcoredump_append_pattern().
>> > + *
>> > + *      HCI_DEVCOREDUMP_DONE: Once the dump collection is complete, the drive
>> > + *              can signal the completion using hci_devcoredump_complete(). A
>> > + *              devcoredump is generated indicating the completion event and
>> > + *              then the state machine is reset to the default state.
>> > + *
>> > + *      HCI_DEVCOREDUMP_ABORT: The driver can cancel ongoing dump collection in
>> > + *              case of any error using hci_devcoredump_abort(). A devcoredump
>> > + *              is still generated with the available data indicating the abort
>> > + *              event and then the state machine is reset to the default state.
>> > + *
>> > + *      HCI_DEVCOREDUMP_TIMEOUT: A timeout timer for HCI_DEVCOREDUMP_TIMEOUT sec
>> > + *              is started during devcoredump initialization. Once the timeout
>> > + *              occurs, the driver is notified, a devcoredump is generated with
>> > + *              the available data indicating the timeout event and then the
>> > + *              state machine is reset to the default state.
>> > + *
>> > + * The driver must register using hci_devcoredump_register() before using the
>> > + * hci devcoredump APIs.
>> > + */
>> > +static void hci_devcoredump_rx(struct work_struct *work)
>> > +{
>> > +       struct hci_dev *hdev = container_of(work, struct hci_dev, dump_rx);
>> > +       struct sk_buff *skb;
>> > +       struct hci_devcoredump_skb_pattern *pattern;
>> > +       u32 dump_size;
>> > +       int start_state;
>> > +
>> > +#define DBG_UNEXPECTED_STATE() \
>> > +               bt_dev_dbg(hdev, \
>> > +                          "Unexpected packet (%d) for state (%d). ", \
>> > +                          hci_dmp_cb(skb)->pkt_type, hdev->dump.state)
>> > +
>> > +       while ((skb = skb_dequeue(&hdev->dump_q))) {
>> > +               hci_dev_lock(hdev);
>> > +               start_state = hdev->dump.state;
>> > +
>> > +               switch (hci_dmp_cb(skb)->pkt_type) {
>> > +               case HCI_DEVCOREDUMP_PKT_INIT:
>> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_IDLE) {
>> > +                               DBG_UNEXPECTED_STATE();
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       if (skb->len != sizeof(dump_size)) {
>> > +                               bt_dev_dbg(hdev, "Invalid dump init pkt");
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       dump_size = *((u32 *)skb->data);
>> > +                       if (!dump_size) {
>> > +                               bt_dev_err(hdev, "Zero size dump init pkt");
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       if (hci_devcoredump_prepare(hdev, dump_size)) {
>> > +                               bt_dev_err(hdev, "Failed to prepare for dump");
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       hci_devcoredump_update_state(hdev,
>> > +                                                    HCI_DEVCOREDUMP_ACTIVE);
>> > +                       queue_delayed_work(hdev->workqueue, &hdev->dump_timeout,
>> > +                                          DEVCOREDUMP_TIMEOUT);
>> > +                       break;
>> > +
>> > +               case HCI_DEVCOREDUMP_PKT_SKB:
>> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> > +                               DBG_UNEXPECTED_STATE();
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       if (!hci_devcoredump_copy(hdev, skb->data, skb->len))
>> > +                               bt_dev_dbg(hdev, "Failed to insert skb");
>> > +                       break;
>> > +
>> > +               case HCI_DEVCOREDUMP_PKT_PATTERN:
>> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> > +                               DBG_UNEXPECTED_STATE();
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       if (skb->len != sizeof(*pattern)) {
>> > +                               bt_dev_dbg(hdev, "Invalid pattern skb");
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       pattern = (void *)skb->data;
>> > +
>> > +                       if (!hci_devcoredump_memset(hdev, pattern->pattern,
>> > +                                                   pattern->len))
>> > +                               bt_dev_dbg(hdev, "Failed to set pattern");
>> > +                       break;
>> > +
>> > +               case HCI_DEVCOREDUMP_PKT_COMPLETE:
>> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> > +                               DBG_UNEXPECTED_STATE();
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       hci_devcoredump_update_state(hdev,
>> > +                                                    HCI_DEVCOREDUMP_DONE);
>> > +                       dump_size = hdev->dump.tail - hdev->dump.head;
>> > +
>> > +                       bt_dev_info(hdev,
>> > +                                   "Devcoredump complete with size %u "
>> > +                                   "(expect %u)",
>> > +                                   dump_size, hdev->dump.alloc_size);
>> > +
>> > +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
>> > +                                     GFP_KERNEL);
>> > +                       break;
>> > +
>> > +               case HCI_DEVCOREDUMP_PKT_ABORT:
>> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> > +                               DBG_UNEXPECTED_STATE();
>> > +                               goto loop_continue;
>> > +                       }
>> > +
>> > +                       hci_devcoredump_update_state(hdev,
>> > +                                                    HCI_DEVCOREDUMP_ABORT);
>> > +                       dump_size = hdev->dump.tail - hdev->dump.head;
>> > +
>> > +                       bt_dev_info(hdev,
>> > +                                   "Devcoredump aborted with size %u "
>> > +                                   "(expect %u)",
>> > +                                   dump_size, hdev->dump.alloc_size);
>> > +
>> > +                       /* Emit a devcoredump with the available data */
>> > +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
>> > +                                     GFP_KERNEL);
>> > +                       break;
>> > +
>> > +               default:
>> > +                       bt_dev_dbg(hdev,
>> > +                                  "Unknown packet (%d) for state (%d). ",
>> > +                                  hci_dmp_cb(skb)->pkt_type, hdev->dump.state);
>> > +                       break;
>> > +               }
>> > +
>> > +loop_continue:
>> > +               kfree_skb(skb);
>> > +               hci_dev_unlock(hdev);
>> > +
>> > +               if (start_state != hdev->dump.state)
>> > +                       hci_devcoredump_notify(hdev, hdev->dump.state);
>> > +
>> > +               hci_dev_lock(hdev);
>> > +               if (hdev->dump.state == HCI_DEVCOREDUMP_DONE ||
>> > +                   hdev->dump.state == HCI_DEVCOREDUMP_ABORT)
>> > +                       hci_devcoredump_reset(hdev);
>> > +               hci_dev_unlock(hdev);
>> > +       }
>> > +}
>> > +
>> > +static void hci_devcoredump_timeout(struct work_struct *work)
>> > +{
>> > +       struct hci_dev *hdev = container_of(work, struct hci_dev,
>> > +                                           dump_timeout.work);
>> > +       u32 dump_size;
>> > +
>> > +       hci_devcoredump_notify(hdev, HCI_DEVCOREDUMP_TIMEOUT);
>> > +
>> > +       hci_dev_lock(hdev);
>> > +
>> > +       cancel_work_sync(&hdev->dump_rx);
>> > +
>> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_TIMEOUT);
>> > +       dump_size = hdev->dump.tail - hdev->dump.head;
>> > +       bt_dev_info(hdev, "Devcoredump timeout with size %u (expect %u)",
>> > +                   dump_size, hdev->dump.alloc_size);
>> > +
>> > +       /* Emit a devcoredump with the available data */
>> > +       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
>> > +
>> > +       hci_devcoredump_reset(hdev);
>> > +
>> > +       hci_dev_unlock(hdev);
>> > +}
>> > +
>> > +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
>> > +                            notify_change_t notify_change)
>> > +{
>> > +       /* driver must implement dmp_hdr() function for bluetooth devcoredump */
>> > +       if (!dmp_hdr)
>> > +               return -EINVAL;
>> > +
>> > +       hci_dev_lock(hdev);
>> > +       hdev->dump.dmp_hdr = dmp_hdr;
>> > +       hdev->dump.notify_change = notify_change;
>> > +       hdev->dump.supported = true;
>> > +       hci_dev_unlock(hdev);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_register);
>> > +
>> > +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size)
>> > +{
>> > +       struct sk_buff *skb = NULL;
>> > +
>> > +       if (!hdev->dump.supported)
>> > +               return -EOPNOTSUPP;
>> > +
>> > +       skb = alloc_skb(sizeof(dmp_size), GFP_ATOMIC);
>> > +       if (!skb) {
>> > +               bt_dev_err(hdev, "Failed to allocate devcoredump init");
>> > +               return -ENOMEM;
>> > +       }
>> > +
>> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_INIT;
>> > +       skb_put_data(skb, &dmp_size, sizeof(dmp_size));
>> > +
>> > +       skb_queue_tail(&hdev->dump_q, skb);
>> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_init);
>> > +
>> > +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb)
>> > +{
>> > +       if (!skb)
>> > +               return -ENOMEM;
>> > +
>> > +       if (!hdev->dump.supported) {
>> > +               kfree_skb(skb);
>> > +               return -EOPNOTSUPP;
>> > +       }
>> > +
>> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_SKB;
>> > +
>> > +       skb_queue_tail(&hdev->dump_q, skb);
>> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_append);
>> > +
>> > +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len)
>> > +{
>> > +       struct hci_devcoredump_skb_pattern p;
>> > +       struct sk_buff *skb = NULL;
>> > +
>> > +       if (!hdev->dump.supported)
>> > +               return -EOPNOTSUPP;
>> > +
>> > +       skb = alloc_skb(sizeof(p), GFP_ATOMIC);
>> > +       if (!skb) {
>> > +               bt_dev_err(hdev, "Failed to allocate devcoredump pattern");
>> > +               return -ENOMEM;
>> > +       }
>> > +
>> > +       p.pattern = pattern;
>> > +       p.len = len;
>> > +
>> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_PATTERN;
>> > +       skb_put_data(skb, &p, sizeof(p));
>> > +
>> > +       skb_queue_tail(&hdev->dump_q, skb);
>> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_append_pattern);
>> > +
>> > +int hci_devcoredump_complete(struct hci_dev *hdev)
>> > +{
>> > +       struct sk_buff *skb = NULL;
>> > +
>> > +       if (!hdev->dump.supported)
>> > +               return -EOPNOTSUPP;
>> > +
>> > +       skb = alloc_skb(0, GFP_ATOMIC);
>> > +       if (!skb) {
>> > +               bt_dev_err(hdev, "Failed to allocate devcoredump complete");
>> > +               return -ENOMEM;
>> > +       }
>> > +
>> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_COMPLETE;
>> > +
>> > +       skb_queue_tail(&hdev->dump_q, skb);
>> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_complete);
>> > +
>> > +int hci_devcoredump_abort(struct hci_dev *hdev)
>> > +{
>> > +       struct sk_buff *skb = NULL;
>> > +
>> > +       if (!hdev->dump.supported)
>> > +               return -EOPNOTSUPP;
>> > +
>> > +       skb = alloc_skb(0, GFP_ATOMIC);
>> > +       if (!skb) {
>> > +               bt_dev_err(hdev, "Failed to allocate devcoredump abort");
>> > +               return -ENOMEM;
>> > +       }
>> > +
>> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_ABORT;
>> > +
>> > +       skb_queue_tail(&hdev->dump_q, skb);
>> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> > +
>> > +       return 0;
>> > +}
>> > +EXPORT_SYMBOL(hci_devcoredump_abort);
>> > +
>> >  /* Alloc HCI device */
>> >  struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>> >  {
>> > @@ -2511,14 +3004,17 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>> >         INIT_WORK(&hdev->tx_work, hci_tx_work);
>> >         INIT_WORK(&hdev->power_on, hci_power_on);
>> >         INIT_WORK(&hdev->error_reset, hci_error_reset);
>> > +       INIT_WORK(&hdev->dump_rx, hci_devcoredump_rx);
>> >
>> >         hci_cmd_sync_init(hdev);
>> >
>> >         INIT_DELAYED_WORK(&hdev->power_off, hci_power_off);
>> > +       INIT_DELAYED_WORK(&hdev->dump_timeout, hci_devcoredump_timeout);
>> >
>> >         skb_queue_head_init(&hdev->rx_q);
>> >         skb_queue_head_init(&hdev->cmd_q);
>> >         skb_queue_head_init(&hdev->raw_q);
>> > +       skb_queue_head_init(&hdev->dump_q);

Perhaps it is a better idea to have this fields as part of a dedicated
struct for coredumps e.g. struct hci_devcoredump, also perhaps they
need to be conditional to CONFIG_DEV_COREDUMP otherwise it just adds
things like a delayed work that will never going to be used, this just
reinforces the need of proper CI tests so we can exercise this code
with the likes of the emulator.

>> >         init_waitqueue_head(&hdev->req_wait_q);
>> >
>> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
>> > index 8f4c5698913d..ec03fa871ef0 100644
>> > --- a/net/bluetooth/hci_sync.c
>> > +++ b/net/bluetooth/hci_sync.c
>> > @@ -3877,6 +3877,8 @@ int hci_dev_open_sync(struct hci_dev *hdev)
>> >                 goto done;
>> >         }
>> >
>> > +       hci_devcoredump_reset(hdev);
>> > +
>> >         set_bit(HCI_RUNNING, &hdev->flags);
>> >         hci_sock_dev_event(hdev, HCI_DEV_OPEN);
>> >
>> > --
>> > 2.35.1.894.gb6a874cedc-goog
>> >
>>
>>
>> --
>> Luiz Augusto von Dentz
>
> Regards,
> Manish.

Hi Manish,

On Thu, Jun 23, 2022 at 12:43 PM Manish Mandlik <mmandlik@google.com> wrote:
>
> Hi Luiz,
>
> On Tue, May 3, 2022 at 5:04 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>>
>> Hi Manish,
>>
>> On Tue, May 3, 2022 at 4:00 PM Manish Mandlik <mmandlik@google.com> wrote:
>> >
>> > Hi Luiz,
>> >
>> > On Mon, Mar 21, 2022 at 9:46 AM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>> >>
>> >> Hi Manish,
>> >>
>> >> On Sun, Mar 20, 2022 at 6:34 PM Manish Mandlik <mmandlik@google.com> wrote:
>> >> >
>> >> > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> >> >
>> >> > Add devcoredump APIs to hci core so that drivers only have to provide
>> >> > the dump skbs instead of managing the synchronization and timeouts.
>> >> >
>> >> > The devcoredump APIs should be used in the following manner:
>> >> >  - hci_devcoredump_init is called to allocate the dump.
>> >> >  - hci_devcoredump_append is called to append any skbs with dump data
>> >> >    OR hci_devcoredump_append_pattern is called to insert a pattern.
>> >> >  - hci_devcoredump_complete is called when all dump packets have been
>> >> >    sent OR hci_devcoredump_abort is called to indicate an error and
>> >> >    cancel an ongoing dump collection.
>> >> >
>> >> > The high level APIs just prepare some skbs with the appropriate data and
>> >> > queue it for the dump to process. Packets part of the crashdump can be
>> >> > intercepted in the driver in interrupt context and forwarded directly to
>> >> > the devcoredump APIs.
>> >>
>> >> If this sort of information comes from telemetry support it can be
>> >> intercepted by other means as well e.g. btmon, in fact I think that
>> >> would have been better since we already dump the backtrace of
>> >> bluetoothd crashes into the monitor as well. Anyway the kernel
>> >> devcoredump support seems to just be dumping the data into sysfs so we
>> >> could be fetching that information from there as well but I'm not
>> >> really sure what we would be gaining with that since we are just
>> >> adding yet another kernel dependency for something that userspace
>> >> could already be doing by itself.
>> >
>> > Currently every vendor has their own way of collecting firmware dumps. The main intention of adding devcoredump support for bluetooth is to provide a unified way to collect firmware crashdumps across all vendors/controllers. This will generate a dump file in the sysfs and vendors can use it for further debugging. There is no plan to include any information from these dumps into the btmon logs.
>> >
>> >>
>> >> > Internally, there are 5 states for the dump: idle, active, complete,
>> >> > abort and timeout. A devcoredump will only be in active state after it
>> >> > has been initialized. Once active, it accepts data to be appended,
>> >> > patterns to be inserted (i.e. memset) and a completion event or an abort
>> >> > event to generate a devcoredump. The timeout is initialized at the same
>> >> > time the dump is initialized (defaulting to 10s) and will be cleared
>> >> > either when the timeout occurs or the dump is complete or aborted.
>> >>
>> >> Is there some userspace component parsing these dumps? Or we will need
>> >> to add some support for the likes of btmon to collect the logs from
>> >> sysfs?
>> >
>> > Yes, user space component is required to parse these dumps. But these tools will be vendor specific and could be proprietary. However, ChromeOS would be using these dumps to identify bluetooth firmware crashes. I'll share more information on ChromeOS use case offline.
>>
>> Fair enough, but we do need some way to exercise this code by the CI,
>> so at very least we need emulator support otherwise it needs to be
>> behind an experimental UUID until proper tests are introduced.
>
> I can add emulator support. Can you please share some instructions/documentation on how to create and run emulator tests? I'll send a separate patch for adding emulator support.

They are the same tests run in CI, have a look at:

https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/test-runner.txt

>>
>>
>> >>
>> >>
>> >> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> >> > Signed-off-by: Manish Mandlik <mmandlik@google.com>
>> >> > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
>> >> > ---
>> >> >
>> >> >  include/net/bluetooth/hci_core.h |  51 ++++
>> >> >  net/bluetooth/hci_core.c         | 496 +++++++++++++++++++++++++++++++
>> >> >  net/bluetooth/hci_sync.c         |   2 +
>> >> >  3 files changed, 549 insertions(+)
>> >> >
>> >> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
>> >> > index d5377740e99c..818ba3a43e8c 100644
>> >> > --- a/include/net/bluetooth/hci_core.h
>> >> > +++ b/include/net/bluetooth/hci_core.h
>> >> > @@ -118,6 +118,43 @@ enum suspended_state {
>> >> >         BT_SUSPEND_CONFIGURE_WAKE,
>> >> >  };
>> >> >
>> >> > +#define DEVCOREDUMP_TIMEOUT    msecs_to_jiffies(100000)        /* 100 sec */
>> >> > +
>> >> > +typedef int  (*dmp_hdr_t)(struct hci_dev *hdev, char *buf, size_t size);
>> >> > +typedef void (*notify_change_t)(struct hci_dev *hdev, int state);
>> >> > +
>> >> > +/* struct hci_devcoredump - Devcoredump state
>> >> > + *
>> >> > + * @supported: Indicates if FW dump collection is supported by driver
>> >> > + * @state: Current state of dump collection
>> >> > + * @alloc_size: Total size of the dump
>> >> > + * @head: Start of the dump
>> >> > + * @tail: Pointer to current end of dump
>> >> > + * @end: head + alloc_size for easy comparisons
>> >> > + *
>> >> > + * @dmp_hdr: Create a dump header to identify controller/fw/driver info
>> >> > + * @notify_change: Notify driver when devcoredump state has changed
>> >> > + */
>> >> > +struct hci_devcoredump {
>> >> > +       bool            supported;
>> >> > +
>> >> > +       enum devcoredump_state {
>> >> > +               HCI_DEVCOREDUMP_IDLE,
>> >> > +               HCI_DEVCOREDUMP_ACTIVE,
>> >> > +               HCI_DEVCOREDUMP_DONE,
>> >> > +               HCI_DEVCOREDUMP_ABORT,
>> >> > +               HCI_DEVCOREDUMP_TIMEOUT
>> >> > +       } state;
>> >> > +
>> >> > +       u32             alloc_size;
>> >> > +       char            *head;
>> >> > +       char            *tail;
>> >> > +       char            *end;
>> >> > +
>> >> > +       dmp_hdr_t       dmp_hdr;
>> >> > +       notify_change_t notify_change;
>> >> > +};
>> >> > +
>> >> >  struct hci_conn_hash {
>> >> >         struct list_head list;
>> >> >         unsigned int     acl_num;
>> >> > @@ -568,6 +605,11 @@ struct hci_dev {
>> >> >         const char              *fw_info;
>> >> >         struct dentry           *debugfs;
>> >> >
>> >> > +       struct hci_devcoredump  dump;
>> >> > +       struct sk_buff_head     dump_q;
>> >> > +       struct work_struct      dump_rx;
>> >> > +       struct delayed_work     dump_timeout;
>> >> > +
>> >> >         struct device           dev;
>> >> >
>> >> >         struct rfkill           *rfkill;
>> >> > @@ -1308,6 +1350,15 @@ static inline void hci_set_aosp_capable(struct hci_dev *hdev)
>> >> >  #endif
>> >> >  }
>> >> >
>> >> > +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
>> >> > +                            notify_change_t notify_change);
>> >> > +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size);
>> >> > +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb);
>> >> > +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len);
>> >> > +int hci_devcoredump_complete(struct hci_dev *hdev);
>> >> > +int hci_devcoredump_abort(struct hci_dev *hdev);
>> >> > +void hci_devcoredump_reset(struct hci_dev *hdev);
>> >> > +
>> >> >  int hci_dev_open(__u16 dev);
>> >> >  int hci_dev_close(__u16 dev);
>> >> >  int hci_dev_do_close(struct hci_dev *hdev);
>> >> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
>> >> > index b4782a6c1025..76dbb6b28870 100644
>> >> > --- a/net/bluetooth/hci_core.c
>> >> > +++ b/net/bluetooth/hci_core.c
>> >> > @@ -28,6 +28,7 @@
>> >> >  #include <linux/export.h>
>> >> >  #include <linux/rfkill.h>
>> >> >  #include <linux/debugfs.h>
>> >> > +#include <linux/devcoredump.h>
>> >> >  #include <linux/crypto.h>
>> >> >  #include <linux/property.h>
>> >> >  #include <linux/suspend.h>
>> >> > @@ -2404,6 +2405,498 @@ static int hci_suspend_notifier(struct notifier_block *nb, unsigned long action,
>> >> >         return NOTIFY_DONE;
>> >> >  }
>> >> >
>> >> > +enum hci_devcoredump_pkt_type {
>> >> > +       HCI_DEVCOREDUMP_PKT_INIT,
>> >> > +       HCI_DEVCOREDUMP_PKT_SKB,
>> >> > +       HCI_DEVCOREDUMP_PKT_PATTERN,
>> >> > +       HCI_DEVCOREDUMP_PKT_COMPLETE,
>> >> > +       HCI_DEVCOREDUMP_PKT_ABORT,
>> >> > +};
>>
>> I'd move the documentation of the states here, also perhaps we should
>> have the handling of devcoredump in its own file e.g. coredump.c,
>> since hci_core.c is quite big already adding things that are not part
>> of HCI/core specification makes it even bigger.
>
> Since these are just packet types, I'm keeping the documentation of the states with the state machine function hci_devcoredump_rx(). However, I have moved  all hci_devcoredump code to a new file - net/bluetooth/coredump.c.
>
>>
>> >> > +struct hci_devcoredump_skb_cb {
>> >> > +       u16 pkt_type;
>> >> > +};
>> >> > +
>> >> > +struct hci_devcoredump_skb_pattern {
>> >> > +       u8 pattern;
>> >> > +       u32 len;
>> >> > +} __packed;
>> >> > +
>> >> > +#define hci_dmp_cb(skb)        ((struct hci_devcoredump_skb_cb *)((skb)->cb))
>> >> > +
>> >> > +#define MAX_DEVCOREDUMP_HDR_SIZE       512     /* bytes */
>> >> > +
>> >> > +static int hci_devcoredump_update_hdr_state(char *buf, size_t size, int state)
>> >> > +{
>> >> > +       if (!buf)
>> >> > +               return 0;
>> >> > +
>> >> > +       return snprintf(buf, size, "Bluetooth devcoredump\nState: %d\n", state);
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static int hci_devcoredump_update_state(struct hci_dev *hdev, int state)
>> >> > +{
>> >> > +       hdev->dump.state = state;
>> >> > +
>> >> > +       return hci_devcoredump_update_hdr_state(hdev->dump.head,
>> >> > +                                               hdev->dump.alloc_size, state);
>> >> > +}
>> >> > +
>> >> > +static int hci_devcoredump_mkheader(struct hci_dev *hdev, char *buf,
>> >> > +                                   size_t buf_size)
>> >> > +{
>> >> > +       char *ptr = buf;
>> >> > +       size_t rem = buf_size;
>> >> > +       size_t read = 0;
>> >> > +
>> >> > +       read = hci_devcoredump_update_hdr_state(ptr, rem, HCI_DEVCOREDUMP_IDLE);
>> >> > +       read += 1; /* update_hdr_state adds \0 at the end upon state rewrite */
>> >> > +       rem -= read;
>> >> > +       ptr += read;
>> >> > +
>> >> > +       if (hdev->dump.dmp_hdr) {
>> >> > +               /* dmp_hdr() should return number of bytes written */
>> >> > +               read = hdev->dump.dmp_hdr(hdev, ptr, rem);
>> >> > +               rem -= read;
>> >> > +               ptr += read;
>> >> > +       }
>> >> > +
>> >> > +       read = snprintf(ptr, rem, "--- Start dump ---\n");
>> >> > +       rem -= read;
>> >> > +       ptr += read;
>> >> > +
>> >> > +       return buf_size - rem;
>> >> > +}
>> >> > +
>> >> > +/* Do not call with hci_dev_lock since this calls driver code. */
>> >> > +static void hci_devcoredump_notify(struct hci_dev *hdev, int state)
>> >> > +{
>> >> > +       if (hdev->dump.notify_change)
>> >> > +               hdev->dump.notify_change(hdev, state);
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +void hci_devcoredump_reset(struct hci_dev *hdev)
>> >> > +{
>> >> > +       hdev->dump.head = NULL;
>> >> > +       hdev->dump.tail = NULL;
>> >> > +       hdev->dump.alloc_size = 0;
>> >> > +
>> >> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
>> >> > +
>> >> > +       cancel_delayed_work(&hdev->dump_timeout);
>> >> > +       skb_queue_purge(&hdev->dump_q);
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static void hci_devcoredump_free(struct hci_dev *hdev)
>> >> > +{
>> >> > +       if (hdev->dump.head)
>> >> > +               vfree(hdev->dump.head);
>> >> > +
>> >> > +       hci_devcoredump_reset(hdev);
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static int hci_devcoredump_alloc(struct hci_dev *hdev, u32 size)
>> >> > +{
>> >> > +       hdev->dump.head = vmalloc(size);
>> >> > +       if (!hdev->dump.head)
>> >> > +               return -ENOMEM;
>> >> > +
>> >> > +       hdev->dump.alloc_size = size;
>> >> > +       hdev->dump.tail = hdev->dump.head;
>> >> > +       hdev->dump.end = hdev->dump.head + size;
>> >> > +
>> >> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static bool hci_devcoredump_copy(struct hci_dev *hdev, char *buf, u32 size)
>> >> > +{
>> >> > +       if (hdev->dump.tail + size > hdev->dump.end)
>> >> > +               return false;
>> >> > +
>> >> > +       memcpy(hdev->dump.tail, buf, size);
>> >> > +       hdev->dump.tail += size;
>> >> > +
>> >> > +       return true;
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static bool hci_devcoredump_memset(struct hci_dev *hdev, u8 pattern, u32 len)
>> >> > +{
>> >> > +       if (hdev->dump.tail + len > hdev->dump.end)
>> >> > +               return false;
>> >> > +
>> >> > +       memset(hdev->dump.tail, pattern, len);
>> >> > +       hdev->dump.tail += len;
>> >> > +
>> >> > +       return true;
>> >> > +}
>> >> > +
>> >> > +/* Call with hci_dev_lock only. */
>> >> > +static int hci_devcoredump_prepare(struct hci_dev *hdev, u32 dump_size)
>> >> > +{
>> >> > +       char *dump_hdr;
>> >> > +       int dump_hdr_size;
>> >> > +       u32 size;
>> >> > +       int err = 0;
>> >> > +
>> >> > +       dump_hdr = vmalloc(MAX_DEVCOREDUMP_HDR_SIZE);
>> >> > +       if (!dump_hdr) {
>> >> > +               err = -ENOMEM;
>> >> > +               goto hdr_free;
>> >> > +       }
>> >> > +
>> >> > +       dump_hdr_size = hci_devcoredump_mkheader(hdev, dump_hdr,
>> >> > +                                                MAX_DEVCOREDUMP_HDR_SIZE);
>> >> > +       size = dump_hdr_size + dump_size;
>> >> > +
>> >> > +       if (hci_devcoredump_alloc(hdev, size)) {
>> >> > +               err = -ENOMEM;
>> >> > +               goto hdr_free;
>> >> > +       }
>> >> > +
>> >> > +       /* Insert the device header */
>> >> > +       if (!hci_devcoredump_copy(hdev, dump_hdr, dump_hdr_size)) {
>> >> > +               bt_dev_err(hdev, "Failed to insert header");
>> >> > +               hci_devcoredump_free(hdev);
>> >> > +
>> >> > +               err = -ENOMEM;
>> >> > +               goto hdr_free;
>> >> > +       }
>> >> > +
>> >> > +hdr_free:
>> >> > +       if (dump_hdr)
>> >> > +               vfree(dump_hdr);
>> >> > +
>> >> > +       return err;
>> >> > +}
>> >> > +
>> >> > +/* Bluetooth devcoredump state machine.
>> >> > + *
>> >> > + * Devcoredump states:
>> >> > + *
>> >> > + *      HCI_DEVCOREDUMP_IDLE: The default state.
>> >> > + *
>> >> > + *      HCI_DEVCOREDUMP_ACTIVE: A devcoredump will be in this state once it has
>> >> > + *              been initialized using hci_devcoredump_init(). Once active, the
>> >> > + *              driver can append data using hci_devcoredump_append() or insert
>> >> > + *              a pattern using hci_devcoredump_append_pattern().
>> >> > + *
>> >> > + *      HCI_DEVCOREDUMP_DONE: Once the dump collection is complete, the drive
>> >> > + *              can signal the completion using hci_devcoredump_complete(). A
>> >> > + *              devcoredump is generated indicating the completion event and
>> >> > + *              then the state machine is reset to the default state.
>> >> > + *
>> >> > + *      HCI_DEVCOREDUMP_ABORT: The driver can cancel ongoing dump collection in
>> >> > + *              case of any error using hci_devcoredump_abort(). A devcoredump
>> >> > + *              is still generated with the available data indicating the abort
>> >> > + *              event and then the state machine is reset to the default state.
>> >> > + *
>> >> > + *      HCI_DEVCOREDUMP_TIMEOUT: A timeout timer for HCI_DEVCOREDUMP_TIMEOUT sec
>> >> > + *              is started during devcoredump initialization. Once the timeout
>> >> > + *              occurs, the driver is notified, a devcoredump is generated with
>> >> > + *              the available data indicating the timeout event and then the
>> >> > + *              state machine is reset to the default state.
>> >> > + *
>> >> > + * The driver must register using hci_devcoredump_register() before using the
>> >> > + * hci devcoredump APIs.
>> >> > + */
>> >> > +static void hci_devcoredump_rx(struct work_struct *work)
>> >> > +{
>> >> > +       struct hci_dev *hdev = container_of(work, struct hci_dev, dump_rx);
>> >> > +       struct sk_buff *skb;
>> >> > +       struct hci_devcoredump_skb_pattern *pattern;
>> >> > +       u32 dump_size;
>> >> > +       int start_state;
>> >> > +
>> >> > +#define DBG_UNEXPECTED_STATE() \
>> >> > +               bt_dev_dbg(hdev, \
>> >> > +                          "Unexpected packet (%d) for state (%d). ", \
>> >> > +                          hci_dmp_cb(skb)->pkt_type, hdev->dump.state)
>> >> > +
>> >> > +       while ((skb = skb_dequeue(&hdev->dump_q))) {
>> >> > +               hci_dev_lock(hdev);
>> >> > +               start_state = hdev->dump.state;
>> >> > +
>> >> > +               switch (hci_dmp_cb(skb)->pkt_type) {
>> >> > +               case HCI_DEVCOREDUMP_PKT_INIT:
>> >> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_IDLE) {
>> >> > +                               DBG_UNEXPECTED_STATE();
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       if (skb->len != sizeof(dump_size)) {
>> >> > +                               bt_dev_dbg(hdev, "Invalid dump init pkt");
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       dump_size = *((u32 *)skb->data);
>> >> > +                       if (!dump_size) {
>> >> > +                               bt_dev_err(hdev, "Zero size dump init pkt");
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       if (hci_devcoredump_prepare(hdev, dump_size)) {
>> >> > +                               bt_dev_err(hdev, "Failed to prepare for dump");
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       hci_devcoredump_update_state(hdev,
>> >> > +                                                    HCI_DEVCOREDUMP_ACTIVE);
>> >> > +                       queue_delayed_work(hdev->workqueue, &hdev->dump_timeout,
>> >> > +                                          DEVCOREDUMP_TIMEOUT);
>> >> > +                       break;
>> >> > +
>> >> > +               case HCI_DEVCOREDUMP_PKT_SKB:
>> >> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> >> > +                               DBG_UNEXPECTED_STATE();
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       if (!hci_devcoredump_copy(hdev, skb->data, skb->len))
>> >> > +                               bt_dev_dbg(hdev, "Failed to insert skb");
>> >> > +                       break;
>> >> > +
>> >> > +               case HCI_DEVCOREDUMP_PKT_PATTERN:
>> >> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> >> > +                               DBG_UNEXPECTED_STATE();
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       if (skb->len != sizeof(*pattern)) {
>> >> > +                               bt_dev_dbg(hdev, "Invalid pattern skb");
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       pattern = (void *)skb->data;
>> >> > +
>> >> > +                       if (!hci_devcoredump_memset(hdev, pattern->pattern,
>> >> > +                                                   pattern->len))
>> >> > +                               bt_dev_dbg(hdev, "Failed to set pattern");
>> >> > +                       break;
>> >> > +
>> >> > +               case HCI_DEVCOREDUMP_PKT_COMPLETE:
>> >> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> >> > +                               DBG_UNEXPECTED_STATE();
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       hci_devcoredump_update_state(hdev,
>> >> > +                                                    HCI_DEVCOREDUMP_DONE);
>> >> > +                       dump_size = hdev->dump.tail - hdev->dump.head;
>> >> > +
>> >> > +                       bt_dev_info(hdev,
>> >> > +                                   "Devcoredump complete with size %u "
>> >> > +                                   "(expect %u)",
>> >> > +                                   dump_size, hdev->dump.alloc_size);
>> >> > +
>> >> > +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
>> >> > +                                     GFP_KERNEL);
>> >> > +                       break;
>> >> > +
>> >> > +               case HCI_DEVCOREDUMP_PKT_ABORT:
>> >> > +                       if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
>> >> > +                               DBG_UNEXPECTED_STATE();
>> >> > +                               goto loop_continue;
>> >> > +                       }
>> >> > +
>> >> > +                       hci_devcoredump_update_state(hdev,
>> >> > +                                                    HCI_DEVCOREDUMP_ABORT);
>> >> > +                       dump_size = hdev->dump.tail - hdev->dump.head;
>> >> > +
>> >> > +                       bt_dev_info(hdev,
>> >> > +                                   "Devcoredump aborted with size %u "
>> >> > +                                   "(expect %u)",
>> >> > +                                   dump_size, hdev->dump.alloc_size);
>> >> > +
>> >> > +                       /* Emit a devcoredump with the available data */
>> >> > +                       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size,
>> >> > +                                     GFP_KERNEL);
>> >> > +                       break;
>> >> > +
>> >> > +               default:
>> >> > +                       bt_dev_dbg(hdev,
>> >> > +                                  "Unknown packet (%d) for state (%d). ",
>> >> > +                                  hci_dmp_cb(skb)->pkt_type, hdev->dump.state);
>> >> > +                       break;
>> >> > +               }
>> >> > +
>> >> > +loop_continue:
>> >> > +               kfree_skb(skb);
>> >> > +               hci_dev_unlock(hdev);
>> >> > +
>> >> > +               if (start_state != hdev->dump.state)
>> >> > +                       hci_devcoredump_notify(hdev, hdev->dump.state);
>> >> > +
>> >> > +               hci_dev_lock(hdev);
>> >> > +               if (hdev->dump.state == HCI_DEVCOREDUMP_DONE ||
>> >> > +                   hdev->dump.state == HCI_DEVCOREDUMP_ABORT)
>> >> > +                       hci_devcoredump_reset(hdev);
>> >> > +               hci_dev_unlock(hdev);
>> >> > +       }
>> >> > +}
>> >> > +
>> >> > +static void hci_devcoredump_timeout(struct work_struct *work)
>> >> > +{
>> >> > +       struct hci_dev *hdev = container_of(work, struct hci_dev,
>> >> > +                                           dump_timeout.work);
>> >> > +       u32 dump_size;
>> >> > +
>> >> > +       hci_devcoredump_notify(hdev, HCI_DEVCOREDUMP_TIMEOUT);
>> >> > +
>> >> > +       hci_dev_lock(hdev);
>> >> > +
>> >> > +       cancel_work_sync(&hdev->dump_rx);
>> >> > +
>> >> > +       hci_devcoredump_update_state(hdev, HCI_DEVCOREDUMP_TIMEOUT);
>> >> > +       dump_size = hdev->dump.tail - hdev->dump.head;
>> >> > +       bt_dev_info(hdev, "Devcoredump timeout with size %u (expect %u)",
>> >> > +                   dump_size, hdev->dump.alloc_size);
>> >> > +
>> >> > +       /* Emit a devcoredump with the available data */
>> >> > +       dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
>> >> > +
>> >> > +       hci_devcoredump_reset(hdev);
>> >> > +
>> >> > +       hci_dev_unlock(hdev);
>> >> > +}
>> >> > +
>> >> > +int hci_devcoredump_register(struct hci_dev *hdev, dmp_hdr_t dmp_hdr,
>> >> > +                            notify_change_t notify_change)
>> >> > +{
>> >> > +       /* driver must implement dmp_hdr() function for bluetooth devcoredump */
>> >> > +       if (!dmp_hdr)
>> >> > +               return -EINVAL;
>> >> > +
>> >> > +       hci_dev_lock(hdev);
>> >> > +       hdev->dump.dmp_hdr = dmp_hdr;
>> >> > +       hdev->dump.notify_change = notify_change;
>> >> > +       hdev->dump.supported = true;
>> >> > +       hci_dev_unlock(hdev);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_register);
>> >> > +
>> >> > +int hci_devcoredump_init(struct hci_dev *hdev, u32 dmp_size)
>> >> > +{
>> >> > +       struct sk_buff *skb = NULL;
>> >> > +
>> >> > +       if (!hdev->dump.supported)
>> >> > +               return -EOPNOTSUPP;
>> >> > +
>> >> > +       skb = alloc_skb(sizeof(dmp_size), GFP_ATOMIC);
>> >> > +       if (!skb) {
>> >> > +               bt_dev_err(hdev, "Failed to allocate devcoredump init");
>> >> > +               return -ENOMEM;
>> >> > +       }
>> >> > +
>> >> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_INIT;
>> >> > +       skb_put_data(skb, &dmp_size, sizeof(dmp_size));
>> >> > +
>> >> > +       skb_queue_tail(&hdev->dump_q, skb);
>> >> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_init);
>> >> > +
>> >> > +int hci_devcoredump_append(struct hci_dev *hdev, struct sk_buff *skb)
>> >> > +{
>> >> > +       if (!skb)
>> >> > +               return -ENOMEM;
>> >> > +
>> >> > +       if (!hdev->dump.supported) {
>> >> > +               kfree_skb(skb);
>> >> > +               return -EOPNOTSUPP;
>> >> > +       }
>> >> > +
>> >> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_SKB;
>> >> > +
>> >> > +       skb_queue_tail(&hdev->dump_q, skb);
>> >> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_append);
>> >> > +
>> >> > +int hci_devcoredump_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len)
>> >> > +{
>> >> > +       struct hci_devcoredump_skb_pattern p;
>> >> > +       struct sk_buff *skb = NULL;
>> >> > +
>> >> > +       if (!hdev->dump.supported)
>> >> > +               return -EOPNOTSUPP;
>> >> > +
>> >> > +       skb = alloc_skb(sizeof(p), GFP_ATOMIC);
>> >> > +       if (!skb) {
>> >> > +               bt_dev_err(hdev, "Failed to allocate devcoredump pattern");
>> >> > +               return -ENOMEM;
>> >> > +       }
>> >> > +
>> >> > +       p.pattern = pattern;
>> >> > +       p.len = len;
>> >> > +
>> >> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_PATTERN;
>> >> > +       skb_put_data(skb, &p, sizeof(p));
>> >> > +
>> >> > +       skb_queue_tail(&hdev->dump_q, skb);
>> >> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_append_pattern);
>> >> > +
>> >> > +int hci_devcoredump_complete(struct hci_dev *hdev)
>> >> > +{
>> >> > +       struct sk_buff *skb = NULL;
>> >> > +
>> >> > +       if (!hdev->dump.supported)
>> >> > +               return -EOPNOTSUPP;
>> >> > +
>> >> > +       skb = alloc_skb(0, GFP_ATOMIC);
>> >> > +       if (!skb) {
>> >> > +               bt_dev_err(hdev, "Failed to allocate devcoredump complete");
>> >> > +               return -ENOMEM;
>> >> > +       }
>> >> > +
>> >> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_COMPLETE;
>> >> > +
>> >> > +       skb_queue_tail(&hdev->dump_q, skb);
>> >> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_complete);
>> >> > +
>> >> > +int hci_devcoredump_abort(struct hci_dev *hdev)
>> >> > +{
>> >> > +       struct sk_buff *skb = NULL;
>> >> > +
>> >> > +       if (!hdev->dump.supported)
>> >> > +               return -EOPNOTSUPP;
>> >> > +
>> >> > +       skb = alloc_skb(0, GFP_ATOMIC);
>> >> > +       if (!skb) {
>> >> > +               bt_dev_err(hdev, "Failed to allocate devcoredump abort");
>> >> > +               return -ENOMEM;
>> >> > +       }
>> >> > +
>> >> > +       hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_ABORT;
>> >> > +
>> >> > +       skb_queue_tail(&hdev->dump_q, skb);
>> >> > +       queue_work(hdev->workqueue, &hdev->dump_rx);
>> >> > +
>> >> > +       return 0;
>> >> > +}
>> >> > +EXPORT_SYMBOL(hci_devcoredump_abort);
>> >> > +
>> >> >  /* Alloc HCI device */
>> >> >  struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>> >> >  {
>> >> > @@ -2511,14 +3004,17 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>> >> >         INIT_WORK(&hdev->tx_work, hci_tx_work);
>> >> >         INIT_WORK(&hdev->power_on, hci_power_on);
>> >> >         INIT_WORK(&hdev->error_reset, hci_error_reset);
>> >> > +       INIT_WORK(&hdev->dump_rx, hci_devcoredump_rx);
>> >> >
>> >> >         hci_cmd_sync_init(hdev);
>> >> >
>> >> >         INIT_DELAYED_WORK(&hdev->power_off, hci_power_off);
>> >> > +       INIT_DELAYED_WORK(&hdev->dump_timeout, hci_devcoredump_timeout);
>> >> >
>> >> >         skb_queue_head_init(&hdev->rx_q);
>> >> >         skb_queue_head_init(&hdev->cmd_q);
>> >> >         skb_queue_head_init(&hdev->raw_q);
>> >> > +       skb_queue_head_init(&hdev->dump_q);
>>
>> Perhaps it is a better idea to have this fields as part of a dedicated
>> struct for coredumps e.g. struct hci_devcoredump, also perhaps they
>> need to be conditional to CONFIG_DEV_COREDUMP otherwise it just adds
>> things like a delayed work that will never going to be used, this just
>> reinforces the need of proper CI tests so we can exercise this code
>> with the likes of the emulator.
>
> Done. I just submitted a v2 patch series with all above changes. Please take a look.
>
>>
>>
>> >> >         init_waitqueue_head(&hdev->req_wait_q);
>> >> >
>> >> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
>> >> > index 8f4c5698913d..ec03fa871ef0 100644
>> >> > --- a/net/bluetooth/hci_sync.c
>> >> > +++ b/net/bluetooth/hci_sync.c
>> >> > @@ -3877,6 +3877,8 @@ int hci_dev_open_sync(struct hci_dev *hdev)
>> >> >                 goto done;
>> >> >         }
>> >> >
>> >> > +       hci_devcoredump_reset(hdev);
>> >> > +
>> >> >         set_bit(HCI_RUNNING, &hdev->flags);
>> >> >         hci_sock_dev_event(hdev, HCI_DEV_OPEN);
>> >> >
>> >> > --
>> >> > 2.35.1.894.gb6a874cedc-goog
>> >> >
>> >>
>> >>
>> >> --
>> >> Luiz Augusto von Dentz
>> >
>> > Regards,
>> > Manish.
>>
>>
>>
>> --
>> Luiz Augusto von Dentz
>
> Regards,
> Manish.