[PATCH v4 1/3] virtio: synchronize callbacks after device reset

["Michael S. Tsirkin" <mst@redhat.com>]

virtio_reset_device says:
	Note: this guarantees that vq callbacks are not in progress
but in practice, only virtio pci correctly synchronizes the cbs.

On other transports, a callback that is already executing, keeps running
while the driver tears down the state it uses.

Add virtio_synchronize_cbs to virtio_reset_device fixing this for all
transports that correctly implement synchronize_cbs().

Reported-by: Karl Mehltretter <kmehltretter@gmail.com>
Link: https://lore.kernel.org/all/20260818040433.66986-1-kmehltretter@gmail.com/
Fixes: c46eccdaadab ("virtio: document virtio_reset_device")
Tested-by: Karl Mehltretter <kmehltretter@gmail.com>
Acked-by: Karl Mehltretter <kmehltretter@gmail.com>
Assisted-by: LLM
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Notes (changelog):
    unchanged since v2

 drivers/virtio/virtio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index b6c9e927bef5..a8588d7ad109 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -264,6 +264,8 @@ void virtio_reset_device(struct virtio_device *dev)
 #endif
 
 	dev->config->reset(dev);
+	/* Flush pending VQ/configuration callbacks. */
+	virtio_synchronize_cbs(dev);
 }
 EXPORT_SYMBOL_GPL(virtio_reset_device);
 
-- 
MST