scsi: aacraid: Block concurrent hotplug event handling

Currently driver will attempt to process hotplug events concurrently based
on the FW interrupt.

Protect safw update function with a scan mutex.
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/aacraid/aacraid.h

@@ -1565,6 +1565,7 @@ struct aac_dev
 	spinlock_t		fib_lock;
 
 	struct mutex		ioctl_mutex;
+	struct mutex		scan_mutex;
 	struct aac_queue_block *queues;
 	/*
 	 *	The user API will use an IOCTL to register itself to receive

drivers/scsi/aacraid/commsup.c

@@ -1997,7 +1997,9 @@ static void aac_handle_sa_aif(struct aac_dev *dev, struct fib *fibptr)
 	case SA_AIF_LDEV_CHANGE:
 	case SA_AIF_BPCFG_CHANGE:
 
+		mutex_lock(&dev->scan_mutex);
 		aac_update_safw_host_devices(dev, AAC_RESCAN);
+		mutex_unlock(&dev->scan_mutex);
 		break;
 
 	case SA_AIF_BPSTAT_CHANGE:

drivers/scsi/aacraid/linit.c

@@ -1683,6 +1683,7 @@ static int aac_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	spin_lock_init(&aac->fib_lock);
 
 	mutex_init(&aac->ioctl_mutex);
+	mutex_init(&aac->scan_mutex);
 	/*
 	 *	Map in the registers from the adapter.
 	 */