linux-kernel - [PATCH AUTOSEL 4.14 054/127] dmaengine: tegra-apb: Prevent race conditions on channel's freeing

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Date:   Thu, 17 Sep 2020 22:11:07 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dmitry Osipenko <digetx@...il.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Vinod Koul <vkoul@...nel.org>, Sasha Levin <sashal@...nel.org>,
        dmaengine@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 054/127] dmaengine: tegra-apb: Prevent race conditions on channel's freeing

From: Dmitry Osipenko <digetx@...il.com>

[ 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@...il.com>
Acked-by: Jon Hunter <jonathanh@...dia.com>
Link: https://lore.kernel.org/r/20200209163356.6439-5-digetx@gmail.com
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 3402494cadf99..78e098b4bd89e 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1208,8 +1208,7 @@ 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