scsi: ufs: Improve interrupt handling for shared interrupts

[ Upstream commit 127d5f7 ]

For shared interrupts, the interrupt status might be zero, so check that
first.

Link: https://lore.kernel.org/r/20200811133936.19171-2-adrian.hunter@intel.com
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/scsi/ufs/ufshcd.c

@@ -5612,7 +5612,7 @@ static void ufshcd_sl_intr(struct ufs_hba *hba, u32 intr_status)
  */
 static irqreturn_t ufshcd_intr(int irq, void *__hba)
 {
-	u32 intr_status, enabled_intr_status;
+	u32 intr_status, enabled_intr_status = 0;
 	irqreturn_t retval = IRQ_NONE;
 	struct ufs_hba *hba = __hba;
 	int retries = hba->nutrs;
@@ -5626,7 +5626,7 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
 	 * read, make sure we handle them by checking the interrupt status
 	 * again in a loop until we process all of the reqs before returning.
 	 */
-	do {
+	while (intr_status && retries--) {
 		enabled_intr_status =
 			intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
 		if (intr_status)
@@ -5637,7 +5637,7 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
 		}
 
 		intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
-	} while (intr_status && --retries);
+	}
 
 	spin_unlock(hba->host->host_lock);
 	return retval;