[SCSI] mpt2sas: Release spinlock for the raid device list before blocking it

Added code to release the spinlock that is used to protect the
raid device list before calling a function that can block. The
blocking was causing a reschedule, and subsequently it is tried
to acquire the same lock, resulting in a panic (NMI Watchdog
detecting a CPU lockup).
Signed-off-by: NNagalakshmi Nandigama <nagalakshmi.nandigama@lsi.com>
Cc: stable@kernel.org
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

drivers/scsi/mpt2sas/mpt2sas_scsih.c

@@ -6749,6 +6749,7 @@ _scsih_mark_responding_raid_device(struct MPT2SAS_ADAPTER *ioc, u64 wwid,
 			} else
 				sas_target_priv_data = NULL;
 			raid_device->responding = 1;
+			spin_unlock_irqrestore(&ioc->raid_device_lock, flags);
 			starget_printk(KERN_INFO, raid_device->starget,
 			    "handle(0x%04x), wwid(0x%016llx)\n", handle,
 			    (unsigned long long)raid_device->wwid);
@@ -6759,16 +6760,16 @@ _scsih_mark_responding_raid_device(struct MPT2SAS_ADAPTER *ioc, u64 wwid,
 			 */
 			_scsih_init_warpdrive_properties(ioc, raid_device);
 			if (raid_device->handle == handle)
-				goto out;
+				return;
 			printk(KERN_INFO "\thandle changed from(0x%04x)!!!\n",
 			    raid_device->handle);
 			raid_device->handle = handle;
 			if (sas_target_priv_data)
 				sas_target_priv_data->handle = handle;
-			goto out;
+			return;
 		}
 	}
- out:
+
 	spin_unlock_irqrestore(&ioc->raid_device_lock, flags);
 }