Commit 305c1959 authored Jun 07, 2015 by Samuel Pitoiset Committed by Ben Skeggs Jul 27, 2015

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 <samuel.pitoiset@gmail.com>
Signed-off-by: Martin Peres <martin.peres@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

parent 3693d544

drivers/gpu/drm/nouveau/nvkm/engine/pm/base.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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;
		mutex_unlock(&nv_subdev(ppm)->mutex);

		if (ctx != ppm->context)
		return -EBUSY;
		ret = -EBUSY;
		mutex_unlock(&nv_subdev(ppm)->mutex);

		return 0;
		return ret;
		}

		struct nvkm_oclass