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virtio_console: break out of buf poll on remove

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[ Upstream commit 0e7174b9d5 ]

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@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Michael S. Tsirkin
2021-10-05 03:04:10 -04:00
committed by Greg Kroah-Hartman
parent 0c00d38337
commit c97ffb4184
1 changed files with 7 additions and 0 deletions
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7
drivers/char/virtio_console.c
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@@ -1959,6 +1959,13 @@ 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 */