Hello Ben Skeggs,
The patch ff4b42c7532e: "drm/nouveau/pwr: initial implementation" from Oct 15, 2013, leads to the following Smatch warning: "drivers/gpu/drm/nouveau/core/subdev/pwr/base.c:48 nouveau_pwr_send() warn: 'mutex:&subdev->mutex' is sometimes locked here and sometimes unlocked."
drivers/gpu/drm/nouveau/core/subdev/pwr/base.c 35 /* we currently only support a single process at a time waiting 36 * on a synchronous reply, take the PPWR mutex and tell the 37 * receive handler what we're waiting for 38 */ 39 if (reply) { 40 mutex_lock(&subdev->mutex); 41 ppwr->recv.message = message; 42 ppwr->recv.process = process; 43 } 44 45 /* wait for a free slot in the fifo */ 46 addr = nv_rd32(ppwr, 0x10a4a0); 47 if (!nv_wait_ne(ppwr, 0x10a4b0, 0xffffffff, addr ^ 8)) 48 return -EBUSY;
Should we have an if (reply) mutex_unlock(&subdev->mutex) before the return?
49
regards, dan carpenter