linux-kernel - [PATCH 4.9 038/199] dmaengine: coh901318: Fix a double-lock bug

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Message-Id: <20191219183217.027211912@linuxfoundation.org>
Date:   Thu, 19 Dec 2019 19:32:00 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Vinod Koul <vkoul@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 038/199] dmaengine: coh901318: Fix a double-lock bug

From: Jia-Ju Bai <baijiaju1990@...il.com>

[ Upstream commit 627469e4445b9b12e0229b3bdf8564d5ce384dd7 ]

The function coh901318_alloc_chan_resources() calls spin_lock_irqsave()
before calling coh901318_config().
But coh901318_config() calls spin_lock_irqsave() again in its
definition, which may cause a double-lock bug.

Because coh901318_config() is only called by
coh901318_alloc_chan_resources(), the bug fix is to remove the
calls to spin-lock and -unlock functions in coh901318_config().

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Vinod Koul <vkoul@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/dma/coh901318.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/dma/coh901318.c
+++ b/drivers/dma/coh901318.c
@@ -1802,8 +1802,6 @@ static int coh901318_config(struct coh90
 	int channel = cohc->id;
 	void __iomem *virtbase = cohc->base->virtbase;
 
-	spin_lock_irqsave(&cohc->lock, flags);
-
 	if (param)
 		p = param;
 	else
@@ -1823,8 +1821,6 @@ static int coh901318_config(struct coh90
 	coh901318_set_conf(cohc, p->config);
 	coh901318_set_ctrl(cohc, p->ctrl_lli_last);
 
-	spin_unlock_irqrestore(&cohc->lock, flags);
-
 	return 0;
 }