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From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Mark Brown <broonie@kernel.org>, Takashi Iwai <tiwai@suse.de>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org
Subject: [PATCH] ASoC: soc-dapm: Fix comparison of pointers
Date: Tue,  9 Dec 2014 22:53:41 +0100	[thread overview]
Message-ID: <1418162021-32229-1-git-send-email-linux@rasmusvillemoes.dk> (raw)

The idiom 'return a - b;' often used in comparison functions is wrong
unless one is certain the values being compared lie in a sufficiently
small range. In this case dapm_seq_compare would also return 0 if the
->dapm pointers happened to differ by a multiple of 2^32.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---

Notes:
    I don't know if the other occurences of the idiom in this function are
    ok; that depends on whether the values always lie in [0, 2^31-1].

 sound/soc/soc-dapm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index c61cb9cedbcd..a894a7c71557 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1255,8 +1255,10 @@ static int dapm_seq_compare(struct snd_soc_dapm_widget *a,
 	}
 	if (a->reg != b->reg)
 		return a->reg - b->reg;
-	if (a->dapm != b->dapm)
-		return (unsigned long)a->dapm - (unsigned long)b->dapm;
+	if (a->dapm < b->dapm)
+		return -1;
+	if (a->dapm > b->dapm)
+		return 1;
 
 	return 0;
 }
-- 
2.1.3


             reply	other threads:[~2014-12-09 21:53 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-09 21:53 Rasmus Villemoes [this message]
2014-12-12 13:21 ` Mark Brown
2014-12-12 13:43   ` Rasmus Villemoes
2014-12-12 14:17     ` Mark Brown

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