Messages in this thread | | | Date | Wed, 12 Aug 2020 09:46:38 +0530 | From | Vinod Koul <> | Subject | Re: drivers/dma/xilinx/xilinx_dpdma.c:1172 xilinx_dpdma_synchronize() error: double unlocked 'chan->vchan.lock' (orig line 1170) |
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HI Laurent,
On 12-08-20, 01:50, Laurent Pinchart wrote: > 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@intel.com> > > > > 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. > > > 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);
Lock is held here
> > 1162 if (chan->desc.pending) { > > 1163 vchan_terminate_vdesc(&chan->desc.pending->vdesc);
This should be called with lock held
> > 1164 chan->desc.pending = NULL; > > 1165 } > > 1166 if (chan->desc.active) { > > 1167 vchan_terminate_vdesc(&chan->desc.active->vdesc);
same here
> > 1168 chan->desc.active = NULL; > > 1169 } > > > 1170 spin_unlock_irqrestore(&chan->vchan.lock, flags);
Dropped
> > 1171 > > > 1172 vchan_synchronize(&chan->vchan);
This should be called without lock
So I agree with you, looks like a false positive to me as well
-- ~Vinod
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