1 files changed, 32 insertions, 7 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 704fdc9ebf91..4adaee62ef33 100644
--- 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;
 }