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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: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
This commit is contained in:
Andre Detsch 2008-07-24 10:57:26 +10:00 committed by Jeremy Kerr
parent 9bcab8405c
commit 0855b54322
1 changed files with 6 additions and 12 deletions
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18
arch/powerpc/platforms/cell/spufs/sched.c
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@ -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);