linux-kernel - [PATCH 3.18 007/134] mfd: ab8500-core: Return zero in get_register

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Message-Id: <20190322111210.743329126@linuxfoundation.org>
Date:   Fri, 22 Mar 2019 12:13:40 +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, Dan Carpenter <dan.carpenter@...cle.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 3.18 007/134] mfd: ab8500-core: Return zero in get_register_interruptible()

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 10628e3ecf544fa2e4e24f8e112d95c37884dc98 ]

This function is supposed to return zero on success or negative error
codes on error.  Unfortunately, there is a bug so it sometimes returns
non-zero, positive numbers on success.

I noticed this bug during review and I can't test it.  It does appear
that the return is sometimes propogated back to _regmap_read() where all
non-zero returns are treated as failure so this may affect run time.

Fixes: 47c1697508f2 ("mfd: Align ab8500 with the abx500 interface")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mfd/ab8500-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/ab8500-core.c b/drivers/mfd/ab8500-core.c
index bde2fc0724103..44ebb84c2e747 100644
--- a/drivers/mfd/ab8500-core.c
+++ b/drivers/mfd/ab8500-core.c
@@ -259,7 +259,7 @@ static int get_register_interruptible(struct ab8500 *ab8500, u8 bank,
 	mutex_unlock(&ab8500->lock);
 	dev_vdbg(ab8500->dev, "rd: addr %#x => data %#x\n", addr, ret);
 
-	return ret;
+	return (ret < 0) ? ret : 0;
 }
 
 static int ab8500_get_register(struct device *dev, u8 bank,
-- 
2.19.1