scsi: Do not attempt to rescan suspended devices

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>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 49f768d0ff37..4c2dc8150c6d 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -764,7 +764,7 @@ scsi_template_proc_dir(const struct scsi_host_template *sht);
 #define scsi_template_proc_dir(sht) NULL
 #endif
 extern void scsi_scan_host(struct Scsi_Host *);
-extern void scsi_rescan_device(struct scsi_device *);
+extern int scsi_rescan_device(struct scsi_device *sdev);
 extern void scsi_remove_host(struct Scsi_Host *);
 extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
 extern int scsi_host_busy(struct Scsi_Host *shost);