From 26fd830a999be08eb1453d6574b105b74fad65bb Mon Sep 17 00:00:00 2001 From: Yoshihiro Shimoda Date: Thu, 9 Oct 2014 11:09:00 +0900 Subject: [PATCH] dmaengine: shdma: fix a race condition in __ld_cleanup() This patch fixes a race condition about a list of shdma-base driver. If we don't apply this patch, a dma slave driver (especially a usb peripheral driver) may not be able to start the transfer. If a dma slave driver has a callback, __ld_cleanup() will call the callback before this driver removes the list. After the callback, since the return value of __ld_cleanup() is not zero, shdma_chan_ld_cleanup() calls __ld_cleanup() again. And, __ld_clean() will removes the list. At this time, if a dma slave driver calls dmaengine_submit() before this driver removes the list, this driver will set schan->pm_state to SHDMA_PM_PENDING in shdma_tx_submit(). And then, even if a dma slave driver calls dma_async_issue_pending(), this driver don't start the transfer because the schan->pm_state is SHDMA_PM_PENDING in shdma_issue_pending(). So, this patch adds a new condition in __ld_clean() to check if the schan->pm_state is SHDMA_PM_PENDING or not. Signed-off-by: Yoshihiro Shimoda Signed-off-by: Vinod Koul --- drivers/dma/sh/shdma-base.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c index ed5b0993edfa..3a2adb131d46 100644 --- a/drivers/dma/sh/shdma-base.c +++ b/drivers/dma/sh/shdma-base.c @@ -391,6 +391,8 @@ static dma_async_tx_callback __ld_cleanup(struct shdma_chan *schan, bool all) dev_dbg(schan->dev, "Bring down channel %d\n", schan->id); pm_runtime_put(schan->dev); schan->pm_state = SHDMA_PM_ESTABLISHED; + } else if (schan->pm_state == SHDMA_PM_PENDING) { + shdma_chan_xfer_ld_queue(schan); } } } -- 2.39.5