[SCSI] qla2xxx: Resolve a performance issue in interrupt

Reverted back a change in qla*_intr_handler code that caused an increase in
cpu cycles by allowing interrupts to occur while the instance hardware lock
was being held.  Fix by taking the lock in irqsave mode.
Reported-and-tested-by: Douglas W. Styner <douglas.w.styner@intel.com>
Signed-off-by: Anirban Chakraborty <anirban.chakraborty@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/qla2xxx/qla_isr.c

@@ -37,6 +37,7 @@ qla2100_intr_handler(int irq, void *dev_id)
 	uint16_t	hccr;
 	uint16_t	mb[4];
 	struct rsp_que *rsp;
+	unsigned long	flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
@@ -49,7 +50,7 @@ qla2100_intr_handler(int irq, void *dev_id)
 	reg = &ha->iobase->isp;
 	status = 0;
 
-	spin_lock(&ha->hardware_lock);
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 	vha = pci_get_drvdata(ha->pdev);
 	for (iter = 50; iter--; ) {
 		hccr = RD_REG_WORD(&reg->hccr);
@@ -101,7 +102,7 @@ qla2100_intr_handler(int irq, void *dev_id)
 			RD_REG_WORD(&reg->hccr);
 		}
 	}
-	spin_unlock(&ha->hardware_lock);
+	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	if (test_bit(MBX_INTR_WAIT, &ha->mbx_cmd_flags) &&
 	    (status & MBX_INTERRUPT) && ha->flags.mbox_int) {
@@ -133,6 +134,7 @@ qla2300_intr_handler(int irq, void *dev_id)
 	uint16_t	mb[4];
 	struct rsp_que *rsp;
 	struct qla_hw_data *ha;
+	unsigned long	flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
@@ -145,7 +147,7 @@ qla2300_intr_handler(int irq, void *dev_id)
 	reg = &ha->iobase->isp;
 	status = 0;
 
-	spin_lock(&ha->hardware_lock);
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 	vha = pci_get_drvdata(ha->pdev);
 	for (iter = 50; iter--; ) {
 		stat = RD_REG_DWORD(&reg->u.isp2300.host_status);
@@ -216,7 +218,7 @@ qla2300_intr_handler(int irq, void *dev_id)
 		WRT_REG_WORD(&reg->hccr, HCCR_CLR_RISC_INT);
 		RD_REG_WORD_RELAXED(&reg->hccr);
 	}
-	spin_unlock(&ha->hardware_lock);
+	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	if (test_bit(MBX_INTR_WAIT, &ha->mbx_cmd_flags) &&
 	    (status & MBX_INTERRUPT) && ha->flags.mbox_int) {
@@ -1626,6 +1628,7 @@ qla24xx_intr_handler(int irq, void *dev_id)
 	uint32_t	hccr;
 	uint16_t	mb[4];
 	struct rsp_que *rsp;
+	unsigned long	flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
@@ -1638,7 +1641,7 @@ qla24xx_intr_handler(int irq, void *dev_id)
 	reg = &ha->iobase->isp24;
 	status = 0;
 
-	spin_lock(&ha->hardware_lock);
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 	vha = pci_get_drvdata(ha->pdev);
 	for (iter = 50; iter--; ) {
 		stat = RD_REG_DWORD(&reg->host_status);
@@ -1688,7 +1691,7 @@ qla24xx_intr_handler(int irq, void *dev_id)
 		WRT_REG_DWORD(&reg->hccr, HCCRX_CLR_RISC_INT);
 		RD_REG_DWORD_RELAXED(&reg->hccr);
 	}
-	spin_unlock(&ha->hardware_lock);
+	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	if (test_bit(MBX_INTR_WAIT, &ha->mbx_cmd_flags) &&
 	    (status & MBX_INTERRUPT) && ha->flags.mbox_int) {