[PATCH] scsi: ips: Fix potential deadlock on host->host_lock

[Chengfeng Ye <dg573847474@gmail.com>]

Hard interrupt do_ipsintr() could introduce double locks on
host->host_lock.

<Deadlock #1>
ips_eh_abort()
--> spin_loc(host->host_lock)
<interrupt>
   --> do_ipsintr()
   --> spin_lock(host->host_lock)

This flaw was found by an experimental static analysis tool I am
developing for irq-related deadlock.

To prevent the potential deadlock, the patch use spin_lock_irqsave()
on host->host_lock.

Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
---
 drivers/scsi/ips.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ips.c b/drivers/scsi/ips.c
index bb206509265e..3caab8233d68 100644
--- a/drivers/scsi/ips.c
+++ b/drivers/scsi/ips.c
@@ -776,6 +776,8 @@ int ips_eh_abort(struct scsi_cmnd *SC)
 {
 	ips_ha_t *ha;
 	ips_copp_wait_item_t *item;
+	unsigned long flags;
+
 	int ret;
 	struct Scsi_Host *host;
 
@@ -793,7 +795,7 @@ int ips_eh_abort(struct scsi_cmnd *SC)
 	if (!ha->active)
 		return (FAILED);
 
-	spin_lock(host->host_lock);
+	spin_lock_irqsave(host->host_lock, flags);
 
 	/* See if the command is on the copp queue */
 	item = ha->copp_waitlist.head;
@@ -814,7 +816,7 @@ int ips_eh_abort(struct scsi_cmnd *SC)
 		ret = (FAILED);
 	}
 
-	spin_unlock(host->host_lock);
+	spin_unlock_irqrestore(host->host_lock, flags);
 	return ret;
 }
 
-- 
2.17.1