linux-kernel - [PATCH 3.12 79/84] ALSA: ali5451: Fix out-of-bound position reporting

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Date:   Mon, 17 Oct 2016 09:52:06 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.de>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 79/84] ALSA: ali5451: Fix out-of-bound position reporting

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit db68577966abc1aeae4ec597b3dcfa0d56e92041 upstream.

The pointer callbacks of ali5451 driver may return the value at the
boundary occasionally, and it results in the kernel warning like
  snd_ali5451 0000:00:06.0: BUG: , pos = 16384, buffer size = 16384, period size = 1024

It seems that folding the position offset is enough for fixing the
warning and no ill-effect has been seen by that.

Reported-by: Enrico Mioso <mrkiko.rs@...il.com>
Tested-by: Enrico Mioso <mrkiko.rs@...il.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 sound/pci/ali5451/ali5451.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/pci/ali5451/ali5451.c b/sound/pci/ali5451/ali5451.c
index 3dfa12b670eb..5778eceb41fd 100644
--- a/sound/pci/ali5451/ali5451.c
+++ b/sound/pci/ali5451/ali5451.c
@@ -1422,6 +1422,7 @@ snd_ali_playback_pointer(struct snd_pcm_substream *substream)
 	spin_unlock(&codec->reg_lock);
 	snd_ali_printk("playback pointer returned cso=%xh.\n", cso);
 
+	cso %= runtime->buffer_size;
 	return cso;
 }
 
@@ -1442,6 +1443,7 @@ static snd_pcm_uframes_t snd_ali_pointer(struct snd_pcm_substream *substream)
 	cso = inw(ALI_REG(codec, ALI_CSO_ALPHA_FMS + 2));
 	spin_unlock(&codec->reg_lock);
 
+	cso %= runtime->buffer_size;
 	return cso;
 }
 
-- 
2.10.1