ASoC: rsnd: fix usrcnt decrementing bug

Field usrcnt is unsigned so it cannot be lesser than zero.
The patch fixes the check, moves it to the beginning of the function
and changes return value to -EIO in case of usercnt error.

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@samsung.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/rcar/ssi.c

@@ -403,29 +403,30 @@ 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 (rsnd_ssi_is_parent(mod, io))
-		goto rsnd_ssi_quit_end;
+	if (!ssi->usrcnt) {
+		dev_err(dev, "%s[%d] usrcnt error\n",
+			rsnd_mod_name(mod), rsnd_mod_id(mod));
+		return -EIO;
+	}
 
-	if (ssi->err > 0)
-		dev_warn(dev, "%s[%d] under/over flow err = %d\n",
-			 rsnd_mod_name(mod), rsnd_mod_id(mod), ssi->err);
+	if (!rsnd_ssi_is_parent(mod, io)) {
+		if (ssi->err > 0)
+			dev_warn(dev, "%s[%d] under/over flow err = %d\n",
+				 rsnd_mod_name(mod), rsnd_mod_id(mod),
+				 ssi->err);
 
-	ssi->cr_own	= 0;
-	ssi->err	= 0;
+		ssi->cr_own	= 0;
+		ssi->err	= 0;
 
-	rsnd_ssi_irq_disable(mod);
+		rsnd_ssi_irq_disable(mod);
+	}
 
-rsnd_ssi_quit_end:
 	rsnd_ssi_master_clk_stop(ssi, io);
 
 	rsnd_mod_power_off(mod);
 
 	ssi->usrcnt--;
 
-	if (ssi->usrcnt < 0)
-		dev_err(dev, "%s[%d] usrcnt error\n",
-			rsnd_mod_name(mod), rsnd_mod_id(mod));
-
 	return 0;
 }