[PATCH 4/4] drivers/misc/sgi-xp/xpc_uv.c: convert nested spin_lock_irqsave to spin_lock

[PATCH 4/4] drivers/misc/sgi-xp/xpc_uv.c: convert nested spin_lock_irqsave to spin_lock

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

If spin_lock_irqsave is called twice in a row with the same second
argument, the interrupt state at the point of the second call overwrites
the value saved by the first call.  Indeed, the second call does not need
to save the interrupt state, so it is changed to a simple spin_lock.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression lock1,lock2;
expression flags;
@@

*spin_lock_irqsave(lock1,flags)
... when != flags
*spin_lock_irqsave(lock2,flags)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 drivers/misc/sgi-xp/xpc_uv.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
index 1f59ee2..7aeaef7 100644
--- a/drivers/misc/sgi-xp/xpc_uv.c
+++ b/drivers/misc/sgi-xp/xpc_uv.c
@@ -451,9 +451,9 @@ 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;
 		}

Re: [PATCH 4/4] drivers/misc/sgi-xp/xpc_uv.c: convert nested spin_lock_irqsave to spin_lock

[Robin Holt]

On Tue, Oct 19, 2010 at 11:43:56AM +0200, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> If spin_lock_irqsave is called twice in a row with the same second
> argument, the interrupt state at the point of the second call overwrites
> the value saved by the first call.  Indeed, the second call does not need
> to save the interrupt state, so it is changed to a simple spin_lock.
> 
> The semantic match that finds this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression lock1,lock2;
> expression flags;
> @@
> 
> *spin_lock_irqsave(lock1,flags)
> ... when != flags
> *spin_lock_irqsave(lock2,flags)
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>

Acked-by: Robin Holt <holt@sgi.com>

> 
> ---
>  drivers/misc/sgi-xp/xpc_uv.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/sgi-xp/xpc_uv.c b/drivers/misc/sgi-xp/xpc_uv.c
> index 1f59ee2..7aeaef7 100644
> --- a/drivers/misc/sgi-xp/xpc_uv.c
> +++ b/drivers/misc/sgi-xp/xpc_uv.c
> @@ -451,9 +451,9 @@ 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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