From: Eric Farman farman@linux.ibm.com
[ Upstream commit 1c06bb87afb2d95b8e9f4f2e3d0d6772c68f3e76 ]
The logic in vfio_ccw_sch_shutdown() always assumed that the input subchannel would point to a vfio_ccw_private struct, without checking that one exists. The blamed commit put in a check for this scenario, to prevent the possibility of a missing private.
The trouble is that check was put alongside a WARN_ON(), presuming that such a scenario would be a cause for concern. But this can be triggered by binding a subchannel to vfio-ccw, and rebooting the system before starting the mdev (via "mdevctl start" or similar) or after stopping it. In those cases, shutdown doesn't need to worry because either the private was never allocated, or it was cleaned up by vfio_ccw_mdev_remove().
Remove the WARN_ON() piece of this check, since there are plausible scenarios where private would be NULL in this path.
Fixes: 9e6f07cd1eaa ("vfio/ccw: create a parent struct") Signed-off-by: Eric Farman farman@linux.ibm.com Reviewed-by: Matthew Rosato mjrosato@linux.ibm.com Link: https://lore.kernel.org/r/20230210174227.2256424-1-farman@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/s390/cio/vfio_ccw_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 54aba7cceb33f..ff538a086fc77 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -225,7 +225,7 @@ static void vfio_ccw_sch_shutdown(struct subchannel *sch) struct vfio_ccw_parent *parent = dev_get_drvdata(&sch->dev); struct vfio_ccw_private *private = dev_get_drvdata(&parent->dev);
- if (WARN_ON(!private)) + if (!private) return;
vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_CLOSE);