pm8001: add a new spinlock to protect the CCB

Patch adds a new spinlock to protect the ccb management.
It may happen that concurrent threads become the same tag value
from the 'alloc' function', the spinlock prevents this situation.
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Suresh Thiagarajan <Suresh.Thiagarajan@pmcs.com>
Acked-by: Jack Wang <xjtuwjp@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/pm8001/pm8001_init.c

@@ -246,6 +246,7 @@ static int pm8001_alloc(struct pm8001_hba_info *pm8001_ha,
 {
 	int i;
 	spin_lock_init(&pm8001_ha->lock);
+	spin_lock_init(&pm8001_ha->bitmap_lock);
 	PM8001_INIT_DBG(pm8001_ha,
 		pm8001_printk("pm8001_alloc: PHY:%x\n",
 				pm8001_ha->chip->n_phy));

drivers/scsi/pm8001/pm8001_sas.c

@@ -77,11 +77,16 @@ inline int pm8001_tag_alloc(struct pm8001_hba_info *pm8001_ha, u32 *tag_out)
 {
 	unsigned int tag;
 	void *bitmap = pm8001_ha->tags;
+	unsigned long flags;
 
+	spin_lock_irqsave(&pm8001_ha->bitmap_lock, flags);
 	tag = find_first_zero_bit(bitmap, pm8001_ha->tags_num);
-	if (tag >= pm8001_ha->tags_num)
+	if (tag >= pm8001_ha->tags_num) {
+		spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
 		return -SAS_QUEUE_FULL;
+	}
 	set_bit(tag, bitmap);
+	spin_unlock_irqrestore(&pm8001_ha->bitmap_lock, flags);
 	*tag_out = tag;
 	return 0;
 }

drivers/scsi/pm8001/pm8001_sas.h

@@ -475,6 +475,7 @@ struct pm8001_hba_info {
 	struct list_head	list;
 	unsigned long		flags;
 	spinlock_t		lock;/* host-wide lock */
+	spinlock_t		bitmap_lock;
 	struct pci_dev		*pdev;/* our device */
 	struct device		*dev;
 	struct pm8001_hba_memspace io_mem[6];