[SCSI] qla2xxx: make msix interrupt handler safe for irq

Yinghai has reported a lockdep warning on qla2xxx:

[ 77.965784] WARNING: at kernel/lockdep.c:2332
trace_hardirqs_on_caller+0xc6/0x14b()
[ 77.977492] Hardware name: Sun
[ 77.979485] Modules linked in:
[ 77.994337] Pid: 0, comm: swapper Not tainted
2.6.33-rc4-tip-yh-03949-g3a8e3f5-dirty #64
[ 78.000120] Call Trace:
[ 78.013298] <IRQ> [<ffffffff81076b54>] warn_slowpath_common+0x7c/0x94
[ 78.017746] [<ffffffff81cd712c>] ? _raw_spin_unlock_irq+0x30/0x36
[ 78.035171] [<ffffffff81076b80>] warn_slowpath_null+0x14/0x16
[ 78.040152] [<ffffffff810a2ae8>] trace_hardirqs_on_caller+0xc6/0x14b
[ 78.055400] [<ffffffff810a2b7a>] trace_hardirqs_on+0xd/0xf
[ 78.058951] [<ffffffff81cd712c>] _raw_spin_unlock_irq+0x30/0x36
[ 78.074889] [<ffffffff816461ef>] qla24xx_msix_default+0x243/0x281
[ 78.091598] [<ffffffff810a5752>] ? __lock_release+0xa5/0xae
[ 78.096799] [<ffffffff810c02ae>] handle_IRQ_event+0x53/0x113
[ 78.111568] [<ffffffff810c2061>] handle_edge_irq+0xf3/0x13b
[ 78.116255] [<ffffffff81035109>] handle_irq+0x24/0x2f
[ 78.132063] [<ffffffff81cdc4b4>] do_IRQ+0x5c/0xc3
[ 78.134684] [<ffffffff81cd7393>] ret_from_intr+0x0/0xf
[ 78.137903] <EOI> [<ffffffff81039a56>] ? mwait_idle+0xaf/0xbb
[ 78.155674] [<ffffffff81039a4d>] ? mwait_idle+0xa6/0xbb
[ 78.158600] [<ffffffff81031c7c>] cpu_idle+0x61/0xa1
[ 78.174333] [<ffffffff81c85d7a>] rest_init+0x7e/0x80
[ 78.178122] [<ffffffff82832d1f>] start_kernel+0x316/0x31d
[ 78.193623] [<ffffffff82832297>] x86_64_start_reservations+0xa7/0xab
[ 78.198924] [<ffffffff8283237f>] x86_64_start_kernel+0xe4/0xeb
[ 78.214540] ---[ end trace be4529f30a2e4ef5 ]---

This was happened when qla2xxx msix interrupt handler is trying to enable
IRQs by spin_unlock_irq(). We should make interrupt handler safe for IRQs,
use spin_lock_irqsave/spin_unlock_irqrestore, this will not break the IRQs
status in interrupt handler.

Reported-by: Yinghai Lu <[e-mail]>
Signed-off-by: Xiaotian Feng <[e-mail]>
Acked-by: Giridhar Malavali <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/qla2xxx/qla_isr.c

···
 	struct rsp_que *rsp;
 	struct device_reg_24xx __iomem *reg;
 	struct scsi_qla_host *vha;
+	unsigned long flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
···
 	ha = rsp->hw;
 	reg = &ha->iobase->isp24;
 
-	spin_lock_irq(&ha->hardware_lock);
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 
 	vha = qla25xx_get_host(rsp);
 	qla24xx_process_response_queue(vha, rsp);
···
 		WRT_REG_DWORD(&reg->hccr, HCCRX_CLR_RISC_INT);
 		RD_REG_DWORD_RELAXED(&reg->hccr);
 	}
-	spin_unlock_irq(&ha->hardware_lock);
+	spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
 	return IRQ_HANDLED;
 }
···
 	struct qla_hw_data *ha;
 	struct rsp_que *rsp;
 	struct device_reg_24xx __iomem *reg;
+	unsigned long flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
···
 	/* Clear the interrupt, if enabled, for this response queue */
 	if (rsp->options & ~BIT_6) {
 		reg = &ha->iobase->isp24;
-		spin_lock_irq(&ha->hardware_lock);
+		spin_lock_irqsave(&ha->hardware_lock, flags);
 		WRT_REG_DWORD(&reg->hccr, HCCRX_CLR_RISC_INT);
 		RD_REG_DWORD_RELAXED(&reg->hccr);
-		spin_unlock_irq(&ha->hardware_lock);
+		spin_unlock_irqrestore(&ha->hardware_lock, flags);
 	}
 	queue_work_on((int) (rsp->id - 1), ha->wq, &rsp->q_work);
 
···
 	uint32_t	stat;
 	uint32_t	hccr;
 	uint16_t	mb[4];
+	unsigned long flags;
 
 	rsp = (struct rsp_que *) dev_id;
 	if (!rsp) {
···
 	reg = &ha->iobase->isp24;
 	status = 0;
 
-	spin_lock_irq(&ha->hardware_lock);
+	spin_lock_irqsave(&ha->hardware_lock, flags);
 	vha = pci_get_drvdata(ha->pdev);
 	do {
 		stat = RD_REG_DWORD(&reg->host_status);
···
 		}
 		WRT_REG_DWORD(&reg->hccr, HCCRX_CLR_RISC_INT);
 	} while (0);
-	spin_unlock_irq(&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) {