| Message ID | 20220705125931.3601-1-vasyl.vavrychuk@opensynergy.com |
|---|---|
| State | New |
| Headers | show |
| Series | Bluetooth: core: Fix deadlock due to `cancel_work_sync(&hdev->power_on)` from hci_power_on_sync. | expand |
This is an automated email and please do not reply to this email. Dear Submitter, Thank you for submitting the patches to the linux bluetooth mailing list. While preparing the CI tests, the patches you submitted couldn't be applied to the current HEAD of the repository. ----- Output ----- error: patch failed: net/bluetooth/hci_core.c:2675 error: net/bluetooth/hci_core.c: patch does not apply hint: Use 'git am --show-current-patch' to see the failed patch Please resolve the issue and submit the patches again. --- Regards, Linux Bluetooth
Hello: This patch was applied to netdev/net.git (master) by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>: On Tue, 5 Jul 2022 15:59:31 +0300 you wrote: > `cancel_work_sync(&hdev->power_on)` was moved to hci_dev_close_sync in > commit [1] to ensure that power_on work is canceled after HCI interface > down. > > But, in certain cases power_on work function may call hci_dev_close_sync > itself: hci_power_on -> hci_dev_do_close -> hci_dev_close_sync -> > cancel_work_sync(&hdev->power_on), causing deadlock. In particular, this > happens when device is rfkilled on boot. To avoid deadlock, move > power_on work canceling out of hci_dev_do_close/hci_dev_close_sync. > > [...] Here is the summary with links: - Bluetooth: core: Fix deadlock due to `cancel_work_sync(&hdev->power_on)` from hci_power_on_sync. https://git.kernel.org/netdev/net/c/e36bea6e78ab You are awesome, thank you!
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c index 59a5c1341c26..a0f99baafd35 100644 --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -571,6 +571,7 @@ int hci_dev_close(__u16 dev) goto done; } + cancel_work_sync(&hdev->power_on); if (hci_dev_test_and_clear_flag(hdev, HCI_AUTO_OFF)) cancel_delayed_work(&hdev->power_off); @@ -2675,6 +2676,8 @@ void hci_unregister_dev(struct hci_dev *hdev) list_del(&hdev->list); write_unlock(&hci_dev_list_lock); + cancel_work_sync(&hdev->power_on); + hci_cmd_sync_clear(hdev); if (!test_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks)) diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index 286d6767f017..1739e8cb3291 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -4088,7 +4088,6 @@ int hci_dev_close_sync(struct hci_dev *hdev) bt_dev_dbg(hdev, ""); - cancel_work_sync(&hdev->power_on); cancel_delayed_work(&hdev->power_off); cancel_delayed_work(&hdev->ncmd_timer);
`cancel_work_sync(&hdev->power_on)` was moved to hci_dev_close_sync in commit [1] to ensure that power_on work is canceled after HCI interface down. But, in certain cases power_on work function may call hci_dev_close_sync itself: hci_power_on -> hci_dev_do_close -> hci_dev_close_sync -> cancel_work_sync(&hdev->power_on), causing deadlock. In particular, this happens when device is rfkilled on boot. To avoid deadlock, move power_on work canceling out of hci_dev_do_close/hci_dev_close_sync. Deadlock introduced by commit [1] was reported in [2,3] as broken suspend. Suspend did not work because `hdev->req_lock` held as result of `power_on` work deadlock. In fact, other BT features were not working. It was not observed when testing [1] since it was verified without rfkill in place. NOTE: It is not needed to cancel power_on work from other places where hci_dev_do_close/hci_dev_close_sync is called in case: * Requests were serialized due to `hdev->req_workqueue`. The power_on work is first in that workqueue. * hci_rfkill_set_block which won't close device anyway until HCI_SETUP is on. * hci_sock_release which runs after hci_sock_bind which ensures HCI_SETUP was cleared. As result, behaviour is the same as in pre-dd06ed7 commit, except power_on work cancel added to hci_dev_close. [1]: commit dd06ed7ad057 ("Bluetooth: core: Fix missing power_on work cancel on HCI close") [2]: https://lore.kernel.org/lkml/20220614181706.26513-1-max.oss.09@gmail.com/ [2]: https://lore.kernel.org/lkml/1236061d-95dd-c3ad-a38f-2dae7aae51ef@o2.pl/ Fixes: commit dd06ed7ad057 ("Bluetooth: core: Fix missing power_on work cancel on HCI close") Signed-off-by: Vasyl Vavrychuk <vasyl.vavrychuk@opensynergy.com> Reported-by: Max Krummenacher <max.krummenacher@toradex.com> Reported-by: Mateusz Jonczyk <mat.jonczyk@o2.pl> --- net/bluetooth/hci_core.c | 3 +++ net/bluetooth/hci_sync.c | 1 - 2 files changed, 3 insertions(+), 1 deletion(-)