Re: [PATCH v3 06/23] scsi: Do not attempt to rescan suspended devices

Hannes Reinecke
2023-09-15T12:29:23Z

On 9/15/23 10:14, Damien Le Moal wrote:
> scsi_rescan_device() takes a scsi device lock before executing a device
> handler and device driver rescan methods. Waiting for the completion of
> any command issued to the device by these methods will thus be done with
> the device lock held. As a result, there is a risk of deadlocking within
> the power management code if scsi_rescan_device() is called to handle a
> device resume with the associated scsi device not yet resumed.
>
> Avoid such situation by checking that the target scsi device is in the
> running state, that is, fully capable of executing commands, before
> proceeding with the rescan and bailout returning -EWOULDBLOCK otherwise.
> With this error return, the caller can retry rescaning the device after
> a delay.
>
> The state check is done with the device lock held and is thus safe
> against incoming suspend power management operations.
>
> Fixes: 6aa0365a3c85 ("ata: libata-scsi: Avoid deadlock on rescan after device resume")
> Cc: stable@vger.kernel.org
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
> ---
> drivers/scsi/scsi_scan.c | 18 +++++++++++++++++-
> include/scsi/scsi_host.h | 2 +-
> 2 files changed, 18 insertions(+), 2 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
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