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author | Andre Detsch <adetsch@br.ibm.com> | 2007-09-19 04:38:12 (GMT) |
---|---|---|
committer | Paul Mackerras <paulus@samba.org> | 2007-09-19 05:12:16 (GMT) |
commit | 36ddbb1380f282b4280c57efdb646dd8647a789f (patch) | |
tree | fbae61d4f858f31ef41631f54d2ab3982f02efb4 /arch/powerpc/platforms/cell/spufs/sched.c | |
parent | 8b0d3121a0b2cf91768ecef635e241b6abc3f1da (diff) | |
download | linux-fsl-qoriq-36ddbb1380f282b4280c57efdb646dd8647a789f.tar.xz |
[POWERPC] spufs: Fix race condition on gang->aff_ref_spu
Affinity reference point location (gang->aff_ref_spu) is reset
when the whole gang is descheduled. However, the last member of
a gang can be descheduled while we are trying to schedule another
member of the gang. This was leading to a race condition, and
the code was using gang->aff_ref_spu in an unsafe manner.
By holding the gang->aff_mutex a little bit longer, and increment
gang->aff_sched_count (which controls when gang->aff_ref_spu
should be reset) a little bit earlier, the problem is fixed.
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/platforms/cell/spufs/sched.c')
-rw-r--r-- | arch/powerpc/platforms/cell/spufs/sched.c | 49 |
1 files changed, 32 insertions, 17 deletions
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c index c784edd..17806e0 100644 --- a/arch/powerpc/platforms/cell/spufs/sched.c +++ b/arch/powerpc/platforms/cell/spufs/sched.c @@ -230,8 +230,6 @@ static void spu_bind_context(struct spu *spu, struct spu_context *ctx) if (ctx->flags & SPU_CREATE_NOSCHED) atomic_inc(&cbe_spu_info[spu->node].reserved_spus); - if (!list_empty(&ctx->aff_list)) - atomic_inc(&ctx->gang->aff_sched_count); ctx->stats.slb_flt_base = spu->stats.slb_flt; ctx->stats.class2_intr_base = spu->stats.class2_intr; @@ -392,7 +390,6 @@ static int has_affinity(struct spu_context *ctx) if (list_empty(&ctx->aff_list)) return 0; - mutex_lock(&gang->aff_mutex); if (!gang->aff_ref_spu) { if (!(gang->aff_flags & AFF_MERGED)) aff_merge_remaining_ctxs(gang); @@ -400,7 +397,6 @@ static int has_affinity(struct spu_context *ctx) aff_set_offsets(gang); aff_set_ref_point_location(gang); } - mutex_unlock(&gang->aff_mutex); return gang->aff_ref_spu != NULL; } @@ -418,9 +414,16 @@ 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 (!list_empty(&ctx->aff_list)) - if (atomic_dec_and_test(&ctx->gang->aff_sched_count)) - ctx->gang->aff_ref_spu = NULL; + + 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); + } + spu_switch_notify(spu, NULL); spu_unmap_mappings(ctx); spu_save(&ctx->csa, spu); @@ -511,20 +514,32 @@ static void spu_prio_wait(struct spu_context *ctx) static struct spu *spu_get_idle(struct spu_context *ctx) { - struct spu *spu; + struct spu *spu, *aff_ref_spu; int node, n; - if (has_affinity(ctx)) { - node = ctx->gang->aff_ref_spu->node; + if (ctx->gang) { + mutex_lock(&ctx->gang->aff_mutex); + if (has_affinity(ctx)) { + aff_ref_spu = ctx->gang->aff_ref_spu; + atomic_inc(&ctx->gang->aff_sched_count); + mutex_unlock(&ctx->gang->aff_mutex); + node = aff_ref_spu->node; - mutex_lock(&cbe_spu_info[node].list_mutex); - spu = ctx_location(ctx->gang->aff_ref_spu, ctx->aff_offset, node); - if (spu && spu->alloc_state == SPU_FREE) - goto found; - mutex_unlock(&cbe_spu_info[node].list_mutex); - return NULL; - } + mutex_lock(&cbe_spu_info[node].list_mutex); + spu = ctx_location(aff_ref_spu, ctx->aff_offset, node); + if (spu && spu->alloc_state == SPU_FREE) + 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); + + return NULL; + } + mutex_unlock(&ctx->gang->aff_mutex); + } node = cpu_to_node(raw_smp_processor_id()); for (n = 0; n < MAX_NUMNODES; n++, node++) { node = (node < MAX_NUMNODES) ? node : 0; |