diff mbox series

[V2,1/2] driver core: Add ability to delete device links of unregistered devices

Message ID 20210709064341.6206-2-adrian.hunter@intel.com
State New
Headers show
Series [V2,1/2] driver core: Add ability to delete device links of unregistered devices | expand

Commit Message

Adrian Hunter July 9, 2021, 6:43 a.m. UTC 
Managed device links are deleted by device_del(). However it is possible to
add a device link to a consumer before device_add(), and then discover an
error prevents the device from being used. In that case normally references
to the device would be dropped and the device would be deleted. However the
device link holds a reference to the device, so the device link and device
remain indefinitely.

Amend device link removal to accept removal of a link with an
unregistered consumer device.

To make that work nicely, the devlink_remove_symlinks() function must be
amended to cope with the absence of the consumer's sysfs presence,
otherwise sysfs_remove_link() will generate a warning.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/base/core.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Comments

Greg Kroah-Hartman July 9, 2021, 9:55 a.m. UTC | #1 
On Fri, Jul 09, 2021 at 09:43:40AM +0300, Adrian Hunter wrote:
> Managed device links are deleted by device_del(). However it is possible to
> add a device link to a consumer before device_add(), and then discover an
> error prevents the device from being used. In that case normally references
> to the device would be dropped and the device would be deleted. However the
> device link holds a reference to the device, so the device link and device
> remain indefinitely.

Why are you not just manually removing the link you just created?  You
manually added it, you know something failed so you need to clean up, so
why not clean this up too?

thanks,

greg k-h
diff mbox series

Patch

diff --git a/drivers/base/core.c b/drivers/base/core.c
index ea5b85354526..24bacdb315c6 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -562,7 +562,8 @@  static void devlink_remove_symlinks(struct device *dev,
 	struct device *con = link->consumer;
 	char *buf;
 
-	sysfs_remove_link(&link->link_dev.kobj, "consumer");
+	if (device_is_registered(con))
+		sysfs_remove_link(&link->link_dev.kobj, "consumer");
 	sysfs_remove_link(&link->link_dev.kobj, "supplier");
 
 	len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
@@ -575,8 +576,10 @@  static void devlink_remove_symlinks(struct device *dev,
 		return;
 	}
 
-	snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
-	sysfs_remove_link(&con->kobj, buf);
+	if (device_is_registered(con)) {
+		snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
+		sysfs_remove_link(&con->kobj, buf);
+	}
 	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
 	sysfs_remove_link(&sup->kobj, buf);
 	kfree(buf);
@@ -885,6 +888,8 @@  static void device_link_put_kref(struct device_link *link)
 {
 	if (link->flags & DL_FLAG_STATELESS)
 		kref_put(&link->kref, __device_link_del);
+	else if (!device_is_registered(link->consumer))
+		__device_link_del(&link->kref);
 	else
 		WARN(1, "Unable to drop a managed device link reference\n");
 }