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authorAndre Detsch <adetsch@br.ibm.com>2008-10-21 11:16:09 +1100
committerJeremy Kerr <jk@ozlabs.org>2008-10-21 11:16:09 +1100
commit34318c253b861f82bd4a2956e6c8ae8ee2c3aae7 (patch)
treeacf2a66a3d569de53a432e452f278b4ebb9b0def /arch
parent10baa26c8ccba6f100397c9ba6534be175762e8d (diff)
powerpc/spufs: Explain conditional decrement of aff_sched_count
This patch adds a comment to clarify why atomic_dec_if_positive is being used to decrement gang's aff_sched_count on SPU context unbind. Signed-off-by: Andre Detsch <adetsch@br.ibm.com> Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/platforms/cell/spufs/sched.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 6253df5a436..2ad914c4749 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -444,6 +444,11 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
if (ctx->gang)
+ /*
+ * If ctx->gang->aff_sched_count is positive, SPU affinity is
+ * being considered in this gang. Using atomic_dec_if_positive
+ * allow us to skip an explicit check for affinity in this gang
+ */
atomic_dec_if_positive(&ctx->gang->aff_sched_count);
spu_switch_notify(spu, NULL);