From: Andre Detsch Date: Tue, 21 Oct 2008 00:16:09 +0000 (+1100) Subject: powerpc/spufs: Explain conditional decrement of aff_sched_count X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=34318c253b861f82bd4a2956e6c8ae8ee2c3aae7;p=openwrt%2Fstaging%2Fblogic.git 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 Signed-off-by: Jeremy Kerr --- diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c index 6253df5a436e..2ad914c47493 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);