ALSA: pcm: Use deferred fasync helper

[linux-2.6-microblaze.git] / sound / core / pcm_native.c

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 704fdc9..ad0541e 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -685,6 +685,24 @@ static int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm,
        return 0;
 }
 
+/* acquire buffer_mutex; if it's in r/w operation, return -EBUSY, otherwise
+ * block the further r/w operations
+ */
+static int snd_pcm_buffer_access_lock(struct snd_pcm_runtime *runtime)
+{
+       if (!atomic_dec_unless_positive(&runtime->buffer_accessing))
+               return -EBUSY;
+       mutex_lock(&runtime->buffer_mutex);
+       return 0; /* keep buffer_mutex, unlocked by below */
+}
+
+/* release buffer_mutex and clear r/w access flag */
+static void snd_pcm_buffer_access_unlock(struct snd_pcm_runtime *runtime)
+{
+       mutex_unlock(&runtime->buffer_mutex);
+       atomic_inc(&runtime->buffer_accessing);
+}
+
 #if IS_ENABLED(CONFIG_SND_PCM_OSS)
 #define is_oss_stream(substream)       ((substream)->oss.oss)
 #else
@@ -695,14 +713,16 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
                             struct snd_pcm_hw_params *params)
 {
        struct snd_pcm_runtime *runtime;
-       int err = 0, usecs;
+       int err, usecs;
        unsigned int bits;
        snd_pcm_uframes_t frames;
 
        if (PCM_RUNTIME_CHECK(substream))
                return -ENXIO;
        runtime = substream->runtime;
-       mutex_lock(&runtime->buffer_mutex);
+       err = snd_pcm_buffer_access_lock(runtime);
+       if (err < 0)
+               return err;
        snd_pcm_stream_lock_irq(substream);
        switch (runtime->status->state) {
        case SNDRV_PCM_STATE_OPEN:
@@ -820,7 +840,7 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream,
                        snd_pcm_lib_free_pages(substream);
        }
  unlock:
-       mutex_unlock(&runtime->buffer_mutex);
+       snd_pcm_buffer_access_unlock(runtime);
        return err;
 }
 
@@ -865,7 +885,9 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
        if (PCM_RUNTIME_CHECK(substream))
                return -ENXIO;
        runtime = substream->runtime;
-       mutex_lock(&runtime->buffer_mutex);
+       result = snd_pcm_buffer_access_lock(runtime);
+       if (result < 0)
+               return result;
        snd_pcm_stream_lock_irq(substream);
        switch (runtime->status->state) {
        case SNDRV_PCM_STATE_SETUP:
@@ -884,7 +906,7 @@ static int snd_pcm_hw_free(struct snd_pcm_substream *substream)
        snd_pcm_set_state(substream, SNDRV_PCM_STATE_OPEN);
        cpu_latency_qos_remove_request(&substream->latency_pm_qos_req);
  unlock:
-       mutex_unlock(&runtime->buffer_mutex);
+       snd_pcm_buffer_access_unlock(runtime);
        return result;
 }
 
@@ -1369,12 +1391,15 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops,
 
        /* Guarantee the group members won't change during non-atomic action */
        down_read(&snd_pcm_link_rwsem);
-       mutex_lock(&substream->runtime->buffer_mutex);
+       res = snd_pcm_buffer_access_lock(substream->runtime);
+       if (res < 0)
+               goto unlock;
        if (snd_pcm_stream_linked(substream))
                res = snd_pcm_action_group(ops, substream, state, false);
        else
                res = snd_pcm_action_single(ops, substream, state);
-       mutex_unlock(&substream->runtime->buffer_mutex);
+       snd_pcm_buffer_access_unlock(substream->runtime);
+ unlock:
        up_read(&snd_pcm_link_rwsem);
        return res;
 }
@@ -3387,6 +3412,8 @@ static long snd_pcm_ioctl(struct file *file, unsigned int cmd,
  * The function is provided primarily for OSS layer and USB gadget drivers,
  * and it allows only the limited set of ioctls (hw_params, sw_params,
  * prepare, start, drain, drop, forward).
+ *
+ * Return: zero if successful, or a negative error code
  */
 int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
                         unsigned int cmd, void *arg)
@@ -3785,6 +3812,8 @@ static const struct vm_operations_struct snd_pcm_vm_ops_data_fault = {
  *
  * This is the default mmap handler for PCM data.  When mmap pcm_ops is NULL,
  * this function is invoked implicitly.
+ *
+ * Return: zero if successful, or a negative error code
  */
 int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
                             struct vm_area_struct *area)
@@ -3811,6 +3840,8 @@ EXPORT_SYMBOL_GPL(snd_pcm_lib_default_mmap);
  * When your hardware uses the iomapped pages as the hardware buffer and
  * wants to mmap it, pass this function as mmap pcm_ops.  Note that this
  * is supposed to work only on limited architectures.
+ *
+ * Return: zero if successful, or a negative error code
  */
 int snd_pcm_lib_mmap_iomem(struct snd_pcm_substream *substream,
                           struct vm_area_struct *area)
@@ -3920,7 +3951,7 @@ static int snd_pcm_fasync(int fd, struct file * file, int on)
        runtime = substream->runtime;
        if (runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED)
                return -EBADFD;
-       return fasync_helper(fd, file, on, &runtime->fasync);
+       return snd_fasync_helper(fd, file, on, &runtime->fasync);
 }
 
 /*