On Tue, Oct 16 2012 at 7:04pm -0400,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> dm-snap: optimize track_chunk
>
> track_chunk is always called with interrupts enabled. Consequently, we
> do not need to save and restore interrupt state in "flags" variable.
> This patch changes spin_lock_irqsave to spin_lock_irq and
> spin_unlock_irqrestore to spin_unlock_irq.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
>
> ---
> drivers/md/dm-snap.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> Index: linux-3.6.2-fast/drivers/md/dm-snap.c
> ===================================================================
> --- linux-3.6.2-fast.orig/drivers/md/dm-snap.c 2012-10-17 00:43:01.000000000 +0200
> +++ linux-3.6.2-fast/drivers/md/dm-snap.c 2012-10-17 00:43:22.000000000 +0200
> @@ -201,14 +201,13 @@ static struct dm_snap_tracked_chunk *tra
> {
> struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
> GFP_NOIO);
> - unsigned long flags;
>
> c->chunk = chunk;
>
> - spin_lock_irqsave(&s->tracked_chunk_lock, flags);
> + spin_lock_irq(&s->tracked_chunk_lock);
Does is make any sense to add "BUG_ON(irqs_disabled());" before the spin_lock_irq?
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