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Subject[PATCH AUTOSEL 4.14 17/67] dmaengine: pl330: fix irq race with terminate_all
Date
From: John Keeping <john@metanate.com>

[ Upstream commit e49756544a21f5625b379b3871d27d8500764670 ]

In pl330_update() when checking if a channel has been aborted, the
channel's lock is not taken, only the overall pl330_dmac lock. But in
pl330_terminate_all() the aborted flag (req_running==-1) is set under
the channel lock and not the pl330_dmac lock.

With threaded interrupts, this leads to a potential race:

pl330_terminate_all pl330_update
------------------- ------------
lock channel
entry
lock pl330
_stop channel
unlock pl330
lock pl330
check req_running != -1
req_running = -1
_start channel

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/dma/pl330.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index d19862f4dc9a..6afd42cfbf5d 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2142,13 +2142,14 @@ static int pl330_terminate_all(struct dma_chan *chan)

pm_runtime_get_sync(pl330->ddma.dev);
spin_lock_irqsave(&pch->lock, flags);
+
spin_lock(&pl330->lock);
_stop(pch->thread);
- spin_unlock(&pl330->lock);
-
pch->thread->req[0].desc = NULL;
pch->thread->req[1].desc = NULL;
pch->thread->req_running = -1;
+ spin_unlock(&pl330->lock);
+
power_down = pch->active;
pch->active = false;

--
2.17.1
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