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Commit 0855b543 authored by Andre Detsch's avatar Andre Detsch Committed by Jeremy Kerr
Browse files

powerpc/spufs: fix aff_mutex and cbe_spu_info[n].list_mutex deadlock 



Currenlt,, it is possible to lock aff_mutex and
cbe_spu_info[n].list_mutex in different orders, allowing a deadlock to
occur. With this change, aff_mutex is not taken within a list_mutex
critical section anymore.

Signed-off-by: default avatarAndre Detsch <adetsch@br.ibm.com>
Signed-off-by: default avatarJeremy Kerr <jk@ozlabs.org>
parent 9bcab840

arch/powerpc/platforms/cell/spufs/sched.c

+6 −12
Original line number Diff line number Diff line
@@ -389,6 +389,9 @@ static int has_affinity(struct spu_context *ctx) 
	if (list_empty(&ctx->aff_list))

		return 0;



	if (atomic_read(&ctx->gang->aff_sched_count) == 0)

		ctx->gang->aff_ref_spu = NULL;



	if (!gang->aff_ref_spu) {

		if (!(gang->aff_flags & AFF_MERGED))

			aff_merge_remaining_ctxs(gang);
@@ -416,14 +419,8 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx) 
 	if (spu->ctx->flags & SPU_CREATE_NOSCHED)

		atomic_dec(&cbe_spu_info[spu->node].reserved_spus);



	if (ctx->gang){

		mutex_lock(&ctx->gang->aff_mutex);

		if (has_affinity(ctx)) {

			if (atomic_dec_and_test(&ctx->gang->aff_sched_count))

				ctx->gang->aff_ref_spu = NULL;

		}

		mutex_unlock(&ctx->gang->aff_mutex);

	}

	if (ctx->gang)

		atomic_dec_if_positive(&ctx->gang->aff_sched_count);



	spu_switch_notify(spu, NULL);

	spu_unmap_mappings(ctx);
@@ -562,10 +559,7 @@ static struct spu *spu_get_idle(struct spu_context *ctx) 
				goto found;

			mutex_unlock(&cbe_spu_info[node].list_mutex);



			mutex_lock(&ctx->gang->aff_mutex);

			if (atomic_dec_and_test(&ctx->gang->aff_sched_count))

				ctx->gang->aff_ref_spu = NULL;

			mutex_unlock(&ctx->gang->aff_mutex);

			atomic_dec(&ctx->gang->aff_sched_count);

			goto not_found;

		}

		mutex_unlock(&ctx->gang->aff_mutex);