Re: [PATCH v7 3/6] s390/vfio-ap: Fix unbounded loop in apq_reset_check()

[sashiko-bot@kernel.org]

> s390/vfio-ap: Fix unbounded loop in apq_reset_check()
> 
> The apq_reset_check() worker polls ap_tapq() in a while(true)
> loop waiting for a queue reset to complete. When ap_tapq()
> returns AP_RESPONSE_BUSY or AP_RESPONSE_RESET_IN_PROGRESS,
> apq_status_check() returns -EBUSY and the loop continues after
> sleeping AP_RESET_INTERVAL (20ms). There is no upper bound on
> how many times the loop iterates, so if the hardware
> continuously returns a busy response the worker runs
> indefinitely.
> 
> This is particularly harmful because several callers of
> vfio_ap_mdev_reset_queue() - such as vfio_ap_mdev_reset_queues(),
> vfio_ap_mdev_reset_qlist() and vfio_ap_mdev_remove_queue() -
> call flush_work() on the queue's reset_work while holding one
> [ ... ]
> status->async == 0
> 
> Fixes: dd174833e44e ("s390/vfio-ap: remove upper limit on wait for queue reset to complete")
> Cc: stable@vger.kernel.org
> Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260904223531.1611088-1-akrowiak@linux.ibm.com?part=3