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.
Fixing this comprehensively needs some thought, and new APIs.
Let's at least handle the specific case of virtio_console
removal that was reported in the field.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1786239
Signed-off-by: Michael S. Tsirkin <[email protected]>
---
drivers/char/virtio_console.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 7eaf303a7a86..c852ce0b4d56 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1956,6 +1956,12 @@ 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 */
--
MST
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