linux-kernel - Re: [PATCH] cx18: Fix a sleep-in-atomic bug in snd_cx18_pcm_hw

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Message-ID: <201706011318.X6bAaEu9%fengguang.wu@intel.com>
Date:   Thu, 1 Jun 2017 13:57:58 +0800
From:   kbuild test robot <lkp@...el.com>
To:     Jia-Ju Bai <baijiaju1990@....com>
Cc:     kbuild-all@...org, awalls@...metrocast.net, mchehab@...nel.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@....com>
Subject: Re: [PATCH] cx18: Fix a sleep-in-atomic bug in snd_cx18_pcm_hw_free

Hi Jia-Ju,

[auto build test WARNING on linuxtv-media/master]
[also build test WARNING on v4.12-rc3 next-20170531]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Jia-Ju-Bai/cx18-Fix-a-sleep-in-atomic-bug-in-snd_cx18_pcm_hw_free/20170601-131553
base:   git://linuxtv.org/media_tree.git master
config: xtensa-allmodconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 4.9.0
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=xtensa 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   drivers/media//pci/cx18/cx18-alsa-pcm.c: In function 'snd_cx18_pcm_hw_free':
>> drivers/media//pci/cx18/cx18-alsa-pcm.c:269:2: warning: 'dma_area' may be used uninitialized in this function [-Wmaybe-uninitialized]
     vfree(dma_area);
     ^

vim +/dma_area +269 drivers/media//pci/cx18/cx18-alsa-pcm.c

   253						   params_buffer_bytes(params));
   254	}
   255	
   256	static int snd_cx18_pcm_hw_free(struct snd_pcm_substream *substream)
   257	{
   258		struct snd_cx18_card *cxsc = snd_pcm_substream_chip(substream);
   259		unsigned long flags;
   260		unsigned char *dma_area;
   261	
   262		spin_lock_irqsave(&cxsc->slock, flags);
   263		if (substream->runtime->dma_area) {
   264			dprintk("freeing pcm capture region\n");
   265			dma_area = substream->runtime->dma_area;
   266			substream->runtime->dma_area = NULL;
   267		}
   268		spin_unlock_irqrestore(&cxsc->slock, flags);
 > 269		vfree(dma_area);
   270	
   271		return 0;
   272	}
   273	
   274	static int snd_cx18_pcm_prepare(struct snd_pcm_substream *substream)
   275	{
   276		struct snd_cx18_card *cxsc = snd_pcm_substream_chip(substream);
   277	

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