drm/nouveau/ltc: protect clearing of comptags with mutex

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/ltc/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/ltc/base.c
index 39c2a38e54f74e6e2a4af834feca795823a21408..0c7ef250dcafc3cbdad15b5cfe79acfd513314fa 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/ltc/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/ltc/base.c
@@ -47,8 +47,10 @@ nvkm_ltc_tags_clear(struct nvkm_ltc *ltc, u32 first, u32 count)
 
        BUG_ON((first > limit) || (limit >= ltc->num_tags));
 
+       mutex_lock(&ltc->subdev.mutex);
        ltc->func->cbc_clear(ltc, first, limit);
        ltc->func->cbc_wait(ltc);
+       mutex_unlock(&ltc->subdev.mutex);
 }
 
 int