scsi: hpsa: correct device resets

Correct a race condition that occurs between the reset handler and the
completion handler. There are times when the wait_event condition is
never met due to this race condition and the reset never completes.

The reset_pending field is NULL initially.

  t  Reset Handler Thread     Completion Thread
  -- --------------------     -----------------
  t1                          if (c->reset_pending)
  t2 c->reset_pending = dev;     if (atomic_dev_and_test(counter))
  t3 atomic_inc(counter)             wait_up_all(event_sync_wait_queue)
  t4
  t5 wait_event(...counter == 0)

Kernel.org Bugzilla:
           https://bugzilla.kernel.org/show_bug.cgi?id=1994350
           Bug 199435 - HPSA + P420i resetting logical Direct-Access
                        never complete
Reviewed-by: Justin Lindley <justin.lindley@microsemi.com>
Reviewed-by: David Carroll <david.carroll@microsemi.com>
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hpsa.h

@@ -76,11 +76,12 @@ struct hpsa_scsi_dev_t {
 	unsigned char raid_level;	/* from inquiry page 0xC1 */
 	unsigned char volume_offline;	/* discovered via TUR or VPD */
 	u16 queue_depth;		/* max queue_depth for this device */
-	atomic_t reset_cmds_out;	/* Count of commands to-be affected */
+	atomic_t commands_outstanding;	/* track commands sent to device */
 	atomic_t ioaccel_cmds_out;	/* Only used for physical devices
 					 * counts commands sent to physical
 					 * device via "ioaccel" path.
 					 */
+	bool in_reset;
 	u32 ioaccel_handle;
 	u8 active_path_index;
 	u8 path_map;

drivers/scsi/hpsa_cmd.h

@@ -448,7 +448,7 @@ struct CommandList {
 	struct hpsa_scsi_dev_t *phys_disk;
 
 	int abort_pending;
-	struct hpsa_scsi_dev_t *reset_pending;
+	struct hpsa_scsi_dev_t *device;
 	atomic_t refcount; /* Must be last to avoid memset in hpsa_cmd_init() */
 } __aligned(COMMANDLIST_ALIGNMENT);