[3.19.y-ckt stable] Patch "ASoC: dapm: Lock during userspace access" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ASoC: dapm: Lock during userspace access

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt6.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From c29e94c438c45911c1cfc426b63682369e45c391 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars at metafoo.de>
Date: Mon, 6 Jul 2015 17:01:24 +0200
Subject: ASoC: dapm: Lock during userspace access

commit e50b1e06b79e9d51efbff9627b4dd407184ef43f upstream.

The DAPM lock must be held when accessing the DAPM graph status through
sysfs or debugfs, otherwise concurrent changes to the graph can result in
undefined behaviour.

Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 sound/soc/soc-dapm.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index 9d56b0b..6b9070f 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -1791,6 +1791,7 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 					   size_t count, loff_t *ppos)
 {
 	struct snd_soc_dapm_widget *w = file->private_data;
+	struct snd_soc_card *card = w->dapm->card;
 	char *buf;
 	int in, out;
 	ssize_t ret;
@@ -1800,6 +1801,8 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 	if (!buf)
 		return -ENOMEM;

+	mutex_lock(&card->dapm_mutex);
+
 	/* Supply widgets are not handled by is_connected_{input,output}_ep() */
 	if (w->is_supply) {
 		in = 0;
@@ -1846,6 +1849,8 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 					p->sink->name);
 	}

+	mutex_unlock(&card->dapm_mutex);
+
 	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);

 	kfree(buf);
@@ -2117,11 +2122,15 @@ static ssize_t dapm_widget_show(struct device *dev,
 	struct snd_soc_pcm_runtime *rtd = dev_get_drvdata(dev);
 	int i, count = 0;

+	mutex_lock(&rtd->card->dapm_mutex);
+
 	for (i = 0; i < rtd->num_codecs; i++) {
 		struct snd_soc_codec *codec = rtd->codec_dais[i]->codec;
 		count += dapm_widget_show_codec(codec, buf + count);
 	}

+	mutex_unlock(&rtd->card->dapm_mutex);
+
 	return count;
 }

--
1.9.1