src/patches/suse-2.6.27.25/patches.arch/ppc-spufs-10-Explain-conditional-decrement-of-aff_.patch

   1 Subject: Explain conditional decrement of aff_sched_count
   2 From: Andre Detsch <adetsch@br.ibm.com>
   3 References: 447133 - LTC50070
   4
   5 This patch adds a comment to clarify why atomic_dec_if_positive is being used
   6 to decrement gang's aff_sched_count on SPU context unbind.
   7
   8 Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
   9 Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
  10 Signed-off-by: Olaf Hering <olh@suse.de>
  11 ---
  12  arch/powerpc/platforms/cell/spufs/sched.c |    5 +++++
  13  1 file changed, 5 insertions(+)
  14
  15 --- a/arch/powerpc/platforms/cell/spufs/sched.c
  16 +++ b/arch/powerpc/platforms/cell/spufs/sched.c
  17 @@ -444,6 +444,11 @@ static void spu_unbind_context(struct sp
  18                 atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
  19
  20         if (ctx->gang)
  21 +               /*
  22 +                * If ctx->gang->aff_sched_count is positive, SPU affinity is
  23 +                * being considered in this gang. Using atomic_dec_if_positive
  24 +                * allow us to skip an explicit check for affinity in this gang
  25 +                */
  26                 atomic_dec_if_positive(&ctx->gang->aff_sched_count);
  27
  28         spu_switch_notify(spu, NULL);