linux-kernel - Re: [PATCH] ASoC: rsnd: fix usrcnt decrementing bug

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Date:	Thu, 24 Dec 2015 00:04:00 +0000
From:	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:	Andrzej Hajda <a.hajda@...sung.com>
CC:	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	"moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
	<alsa-devel@...a-project.org>,
	"open list" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: rsnd: fix usrcnt decrementing bug


Hi Andrzej

> Field usrcnt is unsigned so it cannot be lesser than zero.
> 
> The problem has been detected using proposed semantic patch
> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].
> 
> [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576
> 
> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
> ---

Thank you for your patch. good catch !
I noticed current error case is not good for ssi.c
Can you agree below ?

---------
diff --git a/sound/soc/sh/rcar/ssi.c b/sound/soc/sh/rcar/ssi.c
index 7db05fd..e519e30 100644
--- a/sound/soc/sh/rcar/ssi.c
+++ b/sound/soc/sh/rcar/ssi.c
@@ -403,6 +403,12 @@ static int rsnd_ssi_quit(struct rsnd_mod *mod,
 	struct rsnd_ssi *ssi = rsnd_mod_to_ssi(mod);
 	struct device *dev = rsnd_priv_to_dev(priv);
 
+	if (!ssi->usrcnt) {
+		dev_err(dev, "%s[%d] usrcnt error\n",
+			rsnd_mod_name(mod), rsnd_mod_id(mod));
+		return -EIO;
+	}
+
 	if (rsnd_ssi_is_parent(mod, io))
 		goto rsnd_ssi_quit_end;
 
@@ -422,10 +428,6 @@ rsnd_ssi_quit_end:
 
 	ssi->usrcnt--;
 
-	if (ssi->usrcnt < 0)
-		dev_err(dev, "%s[%d] usrcnt error\n",
-			rsnd_mod_name(mod), rsnd_mod_id(mod));
-
 	return 0;
 }
 
---------


Best regards
---
Kuninori Morimoto
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