On 24/03/2023 09:48, Laurent Pinchart wrote: > On Fri, Mar 24, 2023 at 09:31:35AM +0100, Hans Verkuil wrote: >> On 24/03/2023 09:11, Benjamin Gaignard wrote: >>> >>> Le 24/03/2023 à 06:01, Dan Carpenter a écrit : >>>> Hi Benjamin, >>>> >>>> https://git-scm.com/docs/git-format-patch#_base_tree_information] >>>> >>>> url: https://github.com/intel-lab-lkp/linux/commits/Benjamin-Gaignard/media-videobuf2-Access-vb2_queue-bufs-array-through-helper-functions/20230321-183154 >>>> base: git://linuxtv.org/media_tree.git master >>>> patch link: https://lore.kernel.org/r/20230321102855.346732-3-benjamin.gaignard%40collabora.com >>>> patch subject: [PATCH v2 2/8] media: videobuf2: Make bufs array dynamic allocated >>>> config: arm64-randconfig-m041-20230319 (https://download.01.org/0day-ci/archive/20230324/202303240148.lKRnUqW9-lkp@xxxxxxxxx/config) >>>> compiler: aarch64-linux-gcc (GCC) 12.1.0 >>>> >>>> If you fix the issue, kindly add following tag where applicable >>>> | Reported-by: kernel test robot <lkp@xxxxxxxxx> >>>> | Reported-by: Dan Carpenter <error27@xxxxxxxxx> >>>> | Link: https://lore.kernel.org/r/202303240148.lKRnUqW9-lkp@xxxxxxxxx/ >>>> >>>> smatch warnings: >>>> include/media/videobuf2-core.h:1272 vb2_queue_add_buffer() warn: sleeping in atomic context >>>> drivers/media/common/videobuf2/videobuf2-core.c:2456 vb2_core_queue_init() warn: Please consider using kcalloc instead of kmalloc_array >>>> >>>> vim +1272 include/media/videobuf2-core.h >>>> >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1263 static inline bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb) >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1264 { >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1265 bool ret = false; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1266 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1267 spin_lock(&q->bufs_lock); >>>> ^^^^^^^^^^^^^^^^^^^^^^^ >>>> Holding a spin lock. >>>> >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1268 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1269 if (vb->index >= q->max_num_bufs) { >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1270 struct vb2_buffer **tmp; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1271 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 @1272 tmp = krealloc_array(q->bufs, q->max_num_bufs * 2, sizeof(*q->bufs), GFP_KERNEL); >>>> ^^^^^^^^^^ >>>> Sleeping allocation. GFP_ATOMIC? Or is there a way to move the >>>> allocation outside the lock? >>> >>> I will add GFP_ATOMIC flag in next version. >> >> No need. Instead, don't use realloc here, just allocate a new array, copy over all >> the data from the old, and then switch q->bufs with the spinlock held. Then you >> can free the old one. >> >> It's only when you update q->bufs that you need the lock. > > The copy also needs to be protected by the lock. I suspect that that is not needed, since you shouldn't be able to add buffers here since a mutex should be held at this time. That said, it's something that Benjamin needs to analyze. Regards, Hans > >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1273 if (!tmp) >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1274 goto realloc_failed; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1275 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1276 q->max_num_bufs *= 2; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1277 q->bufs = tmp; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1278 } >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1279 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1280 if (vb->index < q->max_num_bufs) { >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1281 q->bufs[vb->index] = vb; >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1282 ret = true; >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1283 } >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1284 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1285 realloc_failed: >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1286 spin_unlock(&q->bufs_lock); >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1287 >>>> 487d3f14d12ecf Benjamin Gaignard 2023-03-21 1288 return ret; >>>> 625d46c1c1fe8e Benjamin Gaignard 2023-03-21 1289 } >
