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authorAmelie Delaunay2022-10-24 10:36:11 +0200
committerVinod Koul2022-11-08 10:43:56 +0530
commit140fd5e74a1cc7413df88c735fff5ec64d33c1d3 (patch)
tree593e0d646927c5a4f89afdfc8ea00bbd176b97dc /drivers/dma
parentac2b9f34f02052709aea7b34bb2a165e1853eb41 (diff)
dmaengine: stm32-dma: fix potential race between pause and resume
When disabling dma channel, a TCF flag is set and as TCIE is enabled, an interrupt is raised. On a busy system, the interrupt may have latency and the user can ask for dmaengine_resume while stm32-dma driver has not yet managed the complete pause (backup of registers to restore state in resume). To avoid such a case, instead of waiting the interrupt to backup the registers, do it just after disabling the channel and discard Transfer Complete interrupt in case the channel is paused. Fixes: 099a9a94be0e ("dmaengine: stm32-dma: add device_pause/device_resume support") Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com> Link: https://lore.kernel.org/r/20221024083611.132588-1-amelie.delaunay@foss.st.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/stm32-dma.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
index 4891a1767e5a..37674029cb42 100644
--- a/drivers/dma/stm32-dma.c
+++ b/drivers/dma/stm32-dma.c
@@ -675,6 +675,8 @@ static void stm32_dma_handle_chan_paused(struct stm32_dma_chan *chan)
chan->chan_reg.dma_sndtr = stm32_dma_read(dmadev, STM32_DMA_SNDTR(chan->id));
+ chan->status = DMA_PAUSED;
+
dev_dbg(chan2dev(chan), "vchan %pK: paused\n", &chan->vchan);
}
@@ -789,9 +791,7 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
if (status & STM32_DMA_TCI) {
stm32_dma_irq_clear(chan, STM32_DMA_TCI);
if (scr & STM32_DMA_SCR_TCIE) {
- if (chan->status == DMA_PAUSED && !(scr & STM32_DMA_SCR_EN))
- stm32_dma_handle_chan_paused(chan);
- else
+ if (chan->status != DMA_PAUSED)
stm32_dma_handle_chan_done(chan, scr);
}
status &= ~STM32_DMA_TCI;
@@ -838,13 +838,11 @@ static int stm32_dma_pause(struct dma_chan *c)
return -EPERM;
spin_lock_irqsave(&chan->vchan.lock, flags);
+
ret = stm32_dma_disable_chan(chan);
- /*
- * A transfer complete flag is set to indicate the end of transfer due to the stream
- * interruption, so wait for interrupt
- */
if (!ret)
- chan->status = DMA_PAUSED;
+ stm32_dma_handle_chan_paused(chan);
+
spin_unlock_irqrestore(&chan->vchan.lock, flags);
return ret;