RE: [kbuild-all] Re: drivers/dma/xilinx/xilinx_dpdma.c:1172 xilinx_dpdma_synchronize() error: double unlocked 'chan->vchan.lock' (orig line 1170)

[Xia, Hui]

>-----Original Message-----
>From: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>Sent: 2020年8月12日 6:50
>To: kernel test robot <lkp@xxxxxxxxx>
>Cc: Hyun Kwon <hyun.kwon@xxxxxxxxxx>; kbuild-all@xxxxxxxxxxxx; linux-
>kernel@xxxxxxxxxxxxxxx; Vinod Koul <vkoul@xxxxxxxxxx>; Tejas Upadhyay
><tejasu@xxxxxxxxxx>; Michal Simek <monstr@xxxxxxxxx>
>Subject: [kbuild-all] Re: drivers/dma/xilinx/xilinx_dpdma.c:1172
>xilinx_dpdma_synchronize() error: double unlocked 'chan->vchan.lock' (orig line
>1170)
>
>On Wed, Aug 12, 2020 at 06:37:59AM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>> head:   c636eef2ee3696f261a35f34989842701a107895
>> commit: 7cbb0c63de3fc218fd06ecfedb477772a4d12f76 dmaengine: xilinx:
>dpdma: Add the Xilinx DisplayPort DMA engine driver
>> date:   4 weeks ago
>> config: h8300-randconfig-m031-20200811 (attached as .config)
>> compiler: h8300-linux-gcc (GCC) 9.3.0
>>
>> If you fix the issue, kindly add following tag as appropriate
>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>
>> smatch warnings:
>> drivers/dma/xilinx/xilinx_dpdma.c:1172 xilinx_dpdma_synchronize()
>> error: double unlocked 'chan->vchan.lock' (orig line 1170)
>
>Unless I'm mistaken, this is a false positive. I'd appreciate if someone could check
>if I'm missing something obvious.

Please ignore this report. It is a false positive. 
We have changed the rule to avoid send out this warning type directly. Sorry for inconvenient.

Best Regards,
Hui

>
>> vim +1172 drivers/dma/xilinx/xilinx_dpdma.c
>>
>>   1140
>>   1141	/**
>>   1142	 * xilinx_dpdma_synchronize - Synchronize callback execution
>>   1143	 * @dchan: DMA channel
>>   1144	 *
>>   1145	 * Synchronizing callback execution ensures that all previously issued
>>   1146	 * transfers have completed and all associated callbacks have been called
>and
>>   1147	 * have returned.
>>   1148	 *
>>   1149	 * This function waits for the DMA channel to stop. It assumes it has been
>>   1150	 * paused by a previous call to dmaengine_terminate_async(), and that
>no new
>>   1151	 * pending descriptors have been issued with dma_async_issue_pending().
>The
>>   1152	 * behaviour is undefined otherwise.
>>   1153	 */
>>   1154	static void xilinx_dpdma_synchronize(struct dma_chan *dchan)
>>   1155	{
>>   1156		struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
>>   1157		unsigned long flags;
>>   1158
>>   1159		xilinx_dpdma_chan_stop(chan);
>>   1160
>>   1161		spin_lock_irqsave(&chan->vchan.lock, flags);
>>   1162		if (chan->desc.pending) {
>>   1163			vchan_terminate_vdesc(&chan->desc.pending->vdesc);
>>   1164			chan->desc.pending = NULL;
>>   1165		}
>>   1166		if (chan->desc.active) {
>>   1167			vchan_terminate_vdesc(&chan->desc.active->vdesc);
>>   1168			chan->desc.active = NULL;
>>   1169		}
>> > 1170		spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>   1171
>> > 1172		vchan_synchronize(&chan->vchan);
>>   1173	}
>>   1174
>>
>
>--
>Regards,
>
>Laurent Pinchart
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