From 305c1959ea60ddcae5142a20c50db849a40c2a35 Mon Sep 17 00:00:00 2001 From: Samuel Pitoiset Date: Sun, 7 Jun 2015 22:40:12 +0200 Subject: [PATCH] drm/nouveau/pm: fix a potential race condition when creating an engine context There is always the possiblity that the ppm->context pointer would get partially updated and accidentally would equal ctx. This would allow two contexts to co-exist, which is not acceptable. Moving the test to the critical section takes care of this problem. Signed-off-by: Samuel Pitoiset Signed-off-by: Martin Peres Signed-off-by: Ben Skeggs --- drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c b/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c index 274457ca3fef..4cf36a3aa814 100644 --- a/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c +++ b/drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c @@ -358,12 +358,11 @@ nvkm_perfctx_ctor(struct nvkm_object *parent, struct nvkm_object *engine, mutex_lock(&nv_subdev(ppm)->mutex); if (ppm->context == NULL) ppm->context = ctx; + if (ctx != ppm->context) + ret = -EBUSY; mutex_unlock(&nv_subdev(ppm)->mutex); - if (ctx != ppm->context) - return -EBUSY; - - return 0; + return ret; } struct nvkm_oclass