Re: [PATCH v2 0/3] scsi: virtio_scsi: move INIT_WORK calls to virtscsi_init

[Stefan Hajnoczi]

On Thu, Mar 12, 2026 at 06:42:53PM +0100, Joshua Daley wrote:
> Changelog v1 -> v2:
> 
> - Added 2 additional patches:
>   - [PATCH v2 1/3] scsi: virtio_scsi: kick event_list unconditionally
>     - Removes the conditions surrounding event_list operations (suggested by Stefan Hajnoczi <stefanha@xxxxxxxxxx>)
>   - [PATCH v2 2/3] scsi: virtio_scsi: remove unnecessary fn declaration
>     - Removes virtscsi_handle_event() prototype (suggested by Eric Farman <farman@xxxxxxxxxxxxx>)
> 
> - [PATCH 1/1] -> [PATCH v2 3/3] scsi: virtio_scsi: move INIT_WORK calls to virtscsi_init
>   - Removed the condition surrounding INIT_WORK calls
> 
> -----
> 
> v1 cover letter:
> 
> This patch avoids a kernel warning that may occur if a virtio_scsi
> controller is detached immediately following a disk detach. See the
> commit message for details. The following are instructions to
> produce the warning (without the proposed patch).
> 
> Timing matters--if all event work items call INIT_WORK before they are
> flushed by cancel_work_sync, then the warning will not occur.
> 
> The warning will occur consistently if a sleep is added in
> virtscsi_kick_event before the INIT_WORK call, like so:
> 
> #include <linux/delay.h>
> 
> static int virtscsi_kick_event(struct virtio_scsi *vscsi,
> 			       struct virtio_scsi_event_node *event_node)
> {
>     int err;
>     struct scatterlist sg;
>     unsigned long flags;
> 
>  -> msleep(1000);
>     INIT_WORK(&event_node->work, virtscsi_handle_event);
> 	
>     ...
> }
> 
> Then, just detach a disk and its controller in quick succession:
> 
> virsh detach-device --domain <domain> disk.xml; \
> virsh detach-device --domain <domain> controller.xml
> 
> where disk.xml and controller.xml are text files containing the XML
> of the disk and controller.
> 
> Or, with the libvirt python module:
> 
> domain.detachDevice(str(disk_xml))
> domain.detachDevice(str(controller_xml))
> 
> Joshua Daley (3):
>   scsi: virtio_scsi: kick event_list unconditionally
>   scsi: virtio_scsi: remove unnecessary fn declaration
>   scsi: virtio_scsi: move INIT_WORK calls to virtscsi_init
> 
>  drivers/scsi/virtio_scsi.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> -- 
> 2.34.1
> 

Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

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