linux-kernel - [patch] sgi-xp: nested calls to spin_lock

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Message-ID: <20111215064805.GA2776@elgon.mountain>
Date:	Thu, 15 Dec 2011 09:48:05 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Robin Holt <holt@....com>
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [patch] sgi-xp: nested calls to spin_lock_irqsave()

The code here has a nested spin_lock_irqsave().  It's not needed since
IRQs are already disabled and it causes a problem because it means that
IRQs won't be enabled again at the end.  The second call to
spin_lock_irqsave() will overwrite the value of irq_flags and we can't
restore the proper settings.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
This is a static checker fix.  It's possible that no one hits this bug
in real life if the function is always called with IRQs disabled.

diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
index 17bbacb..87b251a 100644
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -452,9 +452,9 @@ xpc_handle_activate_mq_msg_uv(struct xpc_partition *part,
 
 		if (msg->activate_gru_mq_desc_gpa !=
 		    part_uv->activate_gru_mq_desc_gpa) {
-			spin_lock_irqsave(&part_uv->flags_lock, irq_flags);
+			spin_lock(&part_uv->flags_lock);
 			part_uv->flags &= ~XPC_P_CACHED_ACTIVATE_GRU_MQ_DESC_UV;
-			spin_unlock_irqrestore(&part_uv->flags_lock, irq_flags);
+			spin_unlock(&part_uv->flags_lock);
 			part_uv->activate_gru_mq_desc_gpa =
 			    msg->activate_gru_mq_desc_gpa;
 		}
--
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