linux-kernel - [PATCH 3.16 004/202] mfd: ab8500-core: Return zero in get_register

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Date:   Sat, 27 Apr 2019 16:13:09 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Lee Jones" <lee.jones@...aro.org>,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Linus Walleij" <linus.walleij@...aro.org>
Subject: [PATCH 3.16 004/202] mfd: ab8500-core: Return zero in
 get_register_interruptible()

3.16.66-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 10628e3ecf544fa2e4e24f8e112d95c37884dc98 upstream.

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: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mfd/ab8500-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/mfd/ab8500-core.c
+++ b/drivers/mfd/ab8500-core.c
@@ -259,7 +259,7 @@ static int get_register_interruptible(st
 	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,