[PATCH 4.4 37/85] dmaengine: tegra-apb: Prevent race conditions on channels freeing

From: Greg Kroah-Hartman
Date: Tue Sep 29 2020 - 08:47:53 EST


From: Dmitry Osipenko <digetx@xxxxxxxxx>

[ Upstream commit 8e84172e372bdca20c305d92d51d33640d2da431 ]

It's incorrect to check the channel's "busy" state without taking a lock.
That shouldn't cause any real troubles, nevertheless it's always better
not to have any race conditions in the code.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Acked-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200209163356.6439-5-digetx@xxxxxxxxx
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/dma/tegra20-apb-dma.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index b5cf5d36de2b4..68c460a2b16ea 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1207,8 +1207,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)

dev_dbg(tdc2dev(tdc), "Freeing channel %d\n", tdc->id);

- if (tdc->busy)
- tegra_dma_terminate_all(dc);
+ tegra_dma_terminate_all(dc);

spin_lock_irqsave(&tdc->lock, flags);
list_splice_init(&tdc->pending_sg_req, &sg_req_list);
--
2.25.1