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authorYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>2014-10-09 11:09:00 +0900
committerVinod Koul <vinod.koul@intel.com>2014-11-17 13:50:42 +0530
commit26fd830a999be08eb1453d6574b105b74fad65bb (patch)
treef6022a4fb068a58af1a6213d484081b08b3278b8 /drivers/dma
parentce9406380dea1e462ab609700c9daeb6c8b23766 (diff)
downloadlinux-26fd830a999be08eb1453d6574b105b74fad65bb.tar.bz2
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 <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/sh/shdma-base.c2
1 files changed, 2 insertions, 0 deletions
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);
}
}
}