On Thu, Aug 01, 2013 at 03:11:22PM +0200, Tomas Henzl wrote:
> From: Tomas Henzl <thenzl@xxxxxxxxxx>
>
> The cmd_pool_bits is protected everywhere with a spinlock,
> we don't need the test_and_set_bit, set_bit is enough and the loop
> can be removed too.
>
> Signed-off-by: Tomas Henzl <thenzl@xxxxxxxxxx>
> ---
> drivers/scsi/hpsa.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 796482b..d7df01e 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -2662,15 +2662,12 @@ static struct CommandList *cmd_alloc(struct ctlr_info *h)
> unsigned long flags;
>
> spin_lock_irqsave(&h->lock, flags);
> - do {
> - i = find_first_zero_bit(h->cmd_pool_bits, h->nr_cmds);
> - if (i == h->nr_cmds) {
> - spin_unlock_irqrestore(&h->lock, flags);
> - return NULL;
> - }
> - } while (test_and_set_bit
> - (i & (BITS_PER_LONG - 1),
> - h->cmd_pool_bits + (i / BITS_PER_LONG)) != 0);
> + i = find_first_zero_bit(h->cmd_pool_bits, h->nr_cmds);
> + if (i == h->nr_cmds) {
> + spin_unlock_irqrestore(&h->lock, flags);
> + return NULL;
> + }
> + set_bit(i & (BITS_PER_LONG - 1), h->cmd_pool_bits + (i / BITS_PER_LONG));
> h->nr_allocs++;
> spin_unlock_irqrestore(&h->lock, flags);
>
> --
> 1.8.3.1
>
Would it be better instead to just not use the spinlock for protecting
cmd_pool_bits? I have thought about doing this for awhile, but haven't
gotten around to it.
I think the while loop is safe without the spin lock. And then it is
not needed in cmd_free either.
-- steve
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