linux-kernel - Re: [PATCH v2 2/8] media: videobuf2: Make bufs array dynamic allocated

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Message-ID: <a88b93cc-a81f-6186-09fc-02223867e677@collabora.com>
Date:   Fri, 24 Mar 2023 09:11:34 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...labora.com>
To:     Dan Carpenter <error27@...il.com>, oe-kbuild@...ts.linux.dev,
        tfiga@...omium.org, m.szyprowski@...sung.com, mchehab@...nel.org,
        ming.qian@....com, shijie.qin@....com, eagle.zhou@....com,
        bin.liu@...iatek.com, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com, tiffany.lin@...iatek.com,
        andrew-ct.chen@...iatek.com, yunfei.dong@...iatek.com,
        stanimir.k.varbanov@...il.com, quic_vgarodia@...cinc.com,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        ezequiel@...guardiasur.com.ar, p.zabel@...gutronix.de,
        daniel.almeida@...labora.com, hverkuil-cisco@...all.nl,
        laurent.pinchart@...asonboard.com, jernel@...nel.org
Cc:     lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v2 2/8] media: videobuf2: Make bufs array dynamic
 allocated


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@intel.com/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@...el.com>
> | Reported-by: Dan Carpenter <error27@...il.com>
> | Link: https://lore.kernel.org/r/202303240148.lKRnUqW9-lkp@intel.com/
>
> 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.

Thanks for your help,
Benjamin

>
> 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  }
>