This is a note to let you know that I've just added the patch titled
virtio_console: break out of buf poll on remove
to the 5.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio_console-break-out-of-buf-poll-on-remove.patch
and it can be found in the queue-5.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 169481377bd148fa8a764d25dba8d7f50e9b4619
Author: Michael S. Tsirkin <mst@xxxxxxxxxx>
Date: Tue Oct 5 03:04:10 2021 -0400
virtio_console: break out of buf poll on remove
[ Upstream commit 0e7174b9d5877130fec41fb4a16e0c2ee4958d44 ]
A common pattern for device reset is currently:
vdev->config->reset(vdev);
.. cleanup ..
reset prevents new interrupts from arriving and waits for interrupt
handlers to finish.
However if - as is common - the handler queues a work request which is
flushed during the cleanup stage, we have code adding buffers / trying
to get buffers while device is reset. Not good.
This was reproduced by running
modprobe virtio_console
modprobe -r virtio_console
in a loop.
Fix this up by calling virtio_break_device + flush before reset.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 660c5c388c29..f864b17be7e3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1957,6 +1957,13 @@ static void virtcons_remove(struct virtio_device *vdev)
list_del(&portdev->list);
spin_unlock_irq(&pdrvdata_lock);
+ /* Device is going away, exit any polling for buffers */
+ virtio_break_device(vdev);
+ if (use_multiport(portdev))
+ flush_work(&portdev->control_work);
+ else
+ flush_work(&portdev->config_work);
+
/* Disable interrupts for vqs */
vdev->config->reset(vdev);
/* Finish up work that's lined up */
