scsi: core: Fix the unit attention counter implementation

scsi_decide_disposition() may call scsi_check_sense().
scsi_decide_disposition() calls are not serialized. Hence, counter
updates by scsi_check_sense() must be serialized. Hence this patch that
makes the counters updated by scsi_check_sense() atomic.

Cc: Kai Mäkisara <Kai.Makisara@kolumbus.fi>
Fixes: a5d518c ("scsi: core: Add counters for New Media and Power On/Reset UNIT ATTENTIONs")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Link: https://patch.msgid.link/20251014220244.3689508-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: bvanassche

drivers/scsi/scsi_error.c

@@ -554,9 +554,9 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd)
 		 * happened, even if someone else gets the sense data.
 		 */
 		if (sshdr.asc == 0x28)
-			scmd->device->ua_new_media_ctr++;
+			atomic_inc(&sdev->ua_new_media_ctr);
 		else if (sshdr.asc == 0x29)
-			scmd->device->ua_por_ctr++;
+			atomic_inc(&sdev->ua_por_ctr);
 	}
 
 	if (scsi_sense_is_deferred(&sshdr))

include/scsi/scsi_device.h

@@ -252,8 +252,8 @@ struct scsi_device {
 	unsigned int queue_stopped;	/* request queue is quiesced */
 	bool offline_already;		/* Device offline message logged */
 
-	unsigned int ua_new_media_ctr;	/* Counter for New Media UNIT ATTENTIONs */
-	unsigned int ua_por_ctr;	/* Counter for Power On / Reset UAs */
+	atomic_t ua_new_media_ctr;	/* Counter for New Media UNIT ATTENTIONs */
+	atomic_t ua_por_ctr;		/* Counter for Power On / Reset UAs */
 
 	atomic_t disk_events_disable_depth; /* disable depth for disk events */
 
@@ -693,10 +693,8 @@ static inline int scsi_device_busy(struct scsi_device *sdev)
 }
 
 /* Macros to access the UNIT ATTENTION counters */
-#define scsi_get_ua_new_media_ctr(sdev) \
-	((const unsigned int)(sdev->ua_new_media_ctr))
-#define scsi_get_ua_por_ctr(sdev) \
-	((const unsigned int)(sdev->ua_por_ctr))
+#define scsi_get_ua_new_media_ctr(sdev)	atomic_read(&sdev->ua_new_media_ctr)
+#define scsi_get_ua_por_ctr(sdev)	atomic_read(&sdev->ua_por_ctr)
 
 #define MODULE_ALIAS_SCSI_DEVICE(type) \
 	MODULE_ALIAS("scsi:t-" __stringify(type) "*")