linux-kernel - [63/93] ALSA: hda - use WARN_ON_ONCE() for zero-division detection

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Date:	Fri, 19 Feb 2010 08:29:56 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Takashi Iwai <tiwai@...e.de>
Subject: [63/93] ALSA: hda - use WARN_ON_ONCE() for zero-division detection

2.6.32-stable review patch.  If anyone has any objections, please let us know.

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

From: Takashi Iwai <tiwai@...e.de>

commit d6d8bf549393484e906913f02fa3c9518a2819b6 upstream.

Replace the zero-division warning message with WARN_ON_ONCE() per the
advice by Linus.  This shouldn't happen, but if it happens, it's
possible that the bug happens often due to buggy IRQs.

Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 sound/pci/hda/hda_intel.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1858,12 +1858,9 @@ static int azx_position_ok(struct azx *c
 
 	if (!bdl_pos_adj[chip->dev_index])
 		return 1; /* no delayed ack */
-	if (azx_dev->period_bytes == 0) {
-		printk(KERN_WARNING
-		       "hda-intel: Divide by zero was avoided "
-		       "in azx_dev->period_bytes.\n");
-		return 0;
-	}
+	if (WARN_ONCE(!azx_dev->period_bytes,
+		      "hda-intel: zero azx_dev->period_bytes"))
+		return 0; /* this shouldn't happen! */
 	if (pos % azx_dev->period_bytes > azx_dev->period_bytes / 2)
 		return 0; /* NG - it's below the period boundary */
 	return 1; /* OK, it's fine */


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