1 files changed, 43 insertions, 5 deletions

diff --git a/drivers/media/usb/em28xx/em28xx-audio.c b/drivers/media/usb/em28xx/em28xx-audio.c
index f6fcee3d4fb9..f004680219e7 100644
--- a/drivers/media/usb/em28xx/em28xx-audio.c
+++ b/drivers/media/usb/em28xx/em28xx-audio.c
@@ -258,6 +258,13 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
 
         runtime->hw = snd_em28xx_hw_capture;
         if ((dev->alt == 0 || dev->audio_ifnum) && dev->adev.users == 0) {
+                int nonblock = !!(substream->f_flags & O_NONBLOCK);
+
+                if (nonblock) {
+                        if (!mutex_trylock(&dev->lock))
+                                return -EAGAIN;
+                } else
+                        mutex_lock(&dev->lock);
                 if (dev->audio_ifnum)
                         dev->alt = 1;
                 else
@@ -269,7 +276,6 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream)
 
                 /* Sets volume, mute, etc */
                 dev->mute = 0;
-                mutex_lock(&dev->lock);
                 ret = em28xx_audio_analog_set(dev);
                 if (ret < 0)
                         goto err;
@@ -441,11 +447,19 @@ static int em28xx_vol_put(struct snd_kcontrol *kcontrol,
                                struct snd_ctl_elem_value *value)
 {
         struct em28xx *dev = snd_kcontrol_chip(kcontrol);
+        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
         u16 val = (0x1f - (value->value.integer.value[0] & 0x1f)) |
                   (0x1f - (value->value.integer.value[1] & 0x1f)) << 8;
+        int nonblock = 0;
         int rc;
 
-        mutex_lock(&dev->lock);
+        if (substream)
+                nonblock = !!(substream->f_flags & O_NONBLOCK);
+        if (nonblock) {
+                if (!mutex_trylock(&dev->lock))
+                        return -EAGAIN;
+        } else
+                mutex_lock(&dev->lock);
         rc = em28xx_read_ac97(dev, kcontrol->private_value);
         if (rc < 0)
                 goto err;
@@ -470,9 +484,17 @@ static int em28xx_vol_get(struct snd_kcontrol *kcontrol,
                                struct snd_ctl_elem_value *value)
 {
         struct em28xx *dev = snd_kcontrol_chip(kcontrol);
+        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
+        int nonblock = 0;
         int val;
 
-        mutex_lock(&dev->lock);
+        if (substream)
+                nonblock = !!(substream->f_flags & O_NONBLOCK);
+        if (nonblock) {
+                if (!mutex_trylock(&dev->lock))
+                        return -EAGAIN;
+        } else
+                mutex_lock(&dev->lock);
         val = em28xx_read_ac97(dev, kcontrol->private_value);
         mutex_unlock(&dev->lock);
         if (val < 0)
@@ -494,9 +516,17 @@ static int em28xx_vol_put_mute(struct snd_kcontrol *kcontrol,
 {
         struct em28xx *dev = snd_kcontrol_chip(kcontrol);
         u16 val = value->value.integer.value[0];
+        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
+        int nonblock = 0;
         int rc;
 
-        mutex_lock(&dev->lock);
+        if (substream)
+                nonblock = !!(substream->f_flags & O_NONBLOCK);
+        if (nonblock) {
+                if (!mutex_trylock(&dev->lock))
+                        return -EAGAIN;
+        } else
+                mutex_lock(&dev->lock);
         rc = em28xx_read_ac97(dev, kcontrol->private_value);
         if (rc < 0)
                 goto err;
@@ -524,9 +554,17 @@ static int em28xx_vol_get_mute(struct snd_kcontrol *kcontrol,
                                struct snd_ctl_elem_value *value)
 {
         struct em28xx *dev = snd_kcontrol_chip(kcontrol);
+        struct snd_pcm_substream *substream = dev->adev.capture_pcm_substream;
+        int nonblock = 0;
         int val;
 
-        mutex_lock(&dev->lock);
+        if (substream)
+                nonblock = !!(substream->f_flags & O_NONBLOCK);
+        if (nonblock) {
+                if (!mutex_trylock(&dev->lock))
+                        return -EAGAIN;
+        } else
+                mutex_lock(&dev->lock);
         val = em28xx_read_ac97(dev, kcontrol->private_value);
         mutex_unlock(&dev->lock);
         if (val < 0)