ALSA: pcm: Avoid reference to status->state

In the PCM core and driver code, there are lots place referring to the
current PCM state via runtime->status->state.  This patch introduced a
local PCM state in runtime itself and replaces those references with
runtime->state.  It has improvements in two aspects:

- The reduction of a indirect access leads to more code optimization

- It avoids a possible (unexpected) modification of the state via mmap
  of the status record

The status->state is updated together with runtime->state, so that
user-space can still read the current state via mmap like before,
too.

This patch touches only the ALSA core code.  The changes in each
driver will follow in later patches.
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220926135558.26580-2-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/pcm.h

@@ -346,6 +346,8 @@ static inline void snd_pcm_pack_audio_tstamp_report(__u32 *data, __u32 *accuracy
 
 struct snd_pcm_runtime {
 	/* -- Status -- */
+	snd_pcm_state_t state;		/* stream state */
+	snd_pcm_state_t suspended_state; /* suspended stream state */
 	struct snd_pcm_substream *trigger_master;
 	struct timespec64 trigger_tstamp;	/* trigger timestamp */
 	bool trigger_tstamp_latched;     /* trigger timestamp latched in low-level driver/hardware */
@@ -678,11 +680,25 @@ void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
  */
 static inline int snd_pcm_running(struct snd_pcm_substream *substream)
 {
-	return (substream->runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
-		(substream->runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
+	return (substream->runtime->state == SNDRV_PCM_STATE_RUNNING ||
+		(substream->runtime->state == SNDRV_PCM_STATE_DRAINING &&
 		 substream->stream == SNDRV_PCM_STREAM_PLAYBACK));
 }
 
+/**
+ * __snd_pcm_set_state - Change the current PCM state
+ * @runtime: PCM runtime to set
+ * @state: the current state to set
+ *
+ * Call within the stream lock
+ */
+static inline void __snd_pcm_set_state(struct snd_pcm_runtime *runtime,
+				       snd_pcm_state_t state)
+{
+	runtime->state = state;
+	runtime->status->state = state; /* copy for mmap */
+}
+
 /**
  * bytes_to_samples - Unit conversion of the size from bytes to samples
  * @runtime: PCM runtime instance

sound/core/oss/pcm_oss.c

@@ -1237,12 +1237,12 @@ snd_pcm_sframes_t snd_pcm_oss_write3(struct snd_pcm_substream *substream, const
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int ret;
 	while (1) {
-		if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
-		    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+		if (runtime->state == SNDRV_PCM_STATE_XRUN ||
+		    runtime->state == SNDRV_PCM_STATE_SUSPENDED) {
 #ifdef OSS_DEBUG
 			pcm_dbg(substream->pcm,
 				"pcm_oss: write: recovering from %s\n",
-				runtime->status->state == SNDRV_PCM_STATE_XRUN ?
+				runtime->state == SNDRV_PCM_STATE_XRUN ?
 				"XRUN" : "SUSPEND");
 #endif
 			ret = snd_pcm_oss_prepare(substream);
@@ -1257,7 +1257,7 @@ snd_pcm_sframes_t snd_pcm_oss_write3(struct snd_pcm_substream *substream, const
 			break;
 		/* test, if we can't store new data, because the stream */
 		/* has not been started */
-		if (runtime->status->state == SNDRV_PCM_STATE_PREPARED)
+		if (runtime->state == SNDRV_PCM_STATE_PREPARED)
 			return -EAGAIN;
 	}
 	return ret;
@@ -1269,18 +1269,18 @@ snd_pcm_sframes_t snd_pcm_oss_read3(struct snd_pcm_substream *substream, char *p
 	snd_pcm_sframes_t delay;
 	int ret;
 	while (1) {
-		if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
-		    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+		if (runtime->state == SNDRV_PCM_STATE_XRUN ||
+		    runtime->state == SNDRV_PCM_STATE_SUSPENDED) {
 #ifdef OSS_DEBUG
 			pcm_dbg(substream->pcm,
 				"pcm_oss: read: recovering from %s\n",
-				runtime->status->state == SNDRV_PCM_STATE_XRUN ?
+				runtime->state == SNDRV_PCM_STATE_XRUN ?
 				"XRUN" : "SUSPEND");
 #endif
 			ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
 			if (ret < 0)
 				break;
-		} else if (runtime->status->state == SNDRV_PCM_STATE_SETUP) {
+		} else if (runtime->state == SNDRV_PCM_STATE_SETUP) {
 			ret = snd_pcm_oss_prepare(substream);
 			if (ret < 0)
 				break;
@@ -1293,7 +1293,7 @@ snd_pcm_sframes_t snd_pcm_oss_read3(struct snd_pcm_substream *substream, char *p
 					 frames, in_kernel);
 		mutex_lock(&runtime->oss.params_lock);
 		if (ret == -EPIPE) {
-			if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
+			if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
 				ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
 				if (ret < 0)
 					break;
@@ -1312,12 +1312,12 @@ snd_pcm_sframes_t snd_pcm_oss_writev3(struct snd_pcm_substream *substream, void
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int ret;
 	while (1) {
-		if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
-		    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+		if (runtime->state == SNDRV_PCM_STATE_XRUN ||
+		    runtime->state == SNDRV_PCM_STATE_SUSPENDED) {
 #ifdef OSS_DEBUG
 			pcm_dbg(substream->pcm,
 				"pcm_oss: writev: recovering from %s\n",
-				runtime->status->state == SNDRV_PCM_STATE_XRUN ?
+				runtime->state == SNDRV_PCM_STATE_XRUN ?
 				"XRUN" : "SUSPEND");
 #endif
 			ret = snd_pcm_oss_prepare(substream);
@@ -1330,7 +1330,7 @@ snd_pcm_sframes_t snd_pcm_oss_writev3(struct snd_pcm_substream *substream, void
 
 		/* test, if we can't store new data, because the stream */
 		/* has not been started */
-		if (runtime->status->state == SNDRV_PCM_STATE_PREPARED)
+		if (runtime->state == SNDRV_PCM_STATE_PREPARED)
 			return -EAGAIN;
 	}
 	return ret;
@@ -1341,18 +1341,18 @@ snd_pcm_sframes_t snd_pcm_oss_readv3(struct snd_pcm_substream *substream, void *
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int ret;
 	while (1) {
-		if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
-		    runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+		if (runtime->state == SNDRV_PCM_STATE_XRUN ||
+		    runtime->state == SNDRV_PCM_STATE_SUSPENDED) {
 #ifdef OSS_DEBUG
 			pcm_dbg(substream->pcm,
 				"pcm_oss: readv: recovering from %s\n",
-				runtime->status->state == SNDRV_PCM_STATE_XRUN ?
+				runtime->state == SNDRV_PCM_STATE_XRUN ?
 				"XRUN" : "SUSPEND");
 #endif
 			ret = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DRAIN, NULL);
 			if (ret < 0)
 				break;
-		} else if (runtime->status->state == SNDRV_PCM_STATE_SETUP) {
+		} else if (runtime->state == SNDRV_PCM_STATE_SETUP) {
 			ret = snd_pcm_oss_prepare(substream);
 			if (ret < 0)
 				break;
@@ -1635,7 +1635,7 @@ static int snd_pcm_oss_sync1(struct snd_pcm_substream *substream, size_t size)
 		result = 0;
 		set_current_state(TASK_INTERRUPTIBLE);
 		snd_pcm_stream_lock_irq(substream);
-		state = runtime->status->state;
+		state = runtime->state;
 		snd_pcm_stream_unlock_irq(substream);
 		if (state != SNDRV_PCM_STATE_RUNNING) {
 			set_current_state(TASK_RUNNING);
@@ -2854,8 +2854,8 @@ static __poll_t snd_pcm_oss_poll(struct file *file, poll_table * wait)
 		struct snd_pcm_runtime *runtime = psubstream->runtime;
 		poll_wait(file, &runtime->sleep, wait);
 		snd_pcm_stream_lock_irq(psubstream);
-		if (runtime->status->state != SNDRV_PCM_STATE_DRAINING &&
-		    (runtime->status->state != SNDRV_PCM_STATE_RUNNING ||
+		if (runtime->state != SNDRV_PCM_STATE_DRAINING &&
+		    (runtime->state != SNDRV_PCM_STATE_RUNNING ||
 		     snd_pcm_oss_playback_ready(psubstream)))
 			mask |= EPOLLOUT | EPOLLWRNORM;
 		snd_pcm_stream_unlock_irq(psubstream);
@@ -2865,7 +2865,7 @@ static __poll_t snd_pcm_oss_poll(struct file *file, poll_table * wait)
 		snd_pcm_state_t ostate;
 		poll_wait(file, &runtime->sleep, wait);
 		snd_pcm_stream_lock_irq(csubstream);
-		ostate = runtime->status->state;
+		ostate = runtime->state;
 		if (ostate != SNDRV_PCM_STATE_RUNNING ||
 		    snd_pcm_oss_capture_ready(csubstream))
 			mask |= EPOLLIN | EPOLLRDNORM;

sound/core/pcm.c

@@ -387,7 +387,7 @@ static void snd_pcm_substream_proc_hw_params_read(struct snd_info_entry *entry,
 		snd_iprintf(buffer, "closed\n");
 		goto unlock;
 	}
-	if (runtime->status->state == SNDRV_PCM_STATE_OPEN) {
+	if (runtime->state == SNDRV_PCM_STATE_OPEN) {
 		snd_iprintf(buffer, "no setup\n");
 		goto unlock;
 	}
@@ -424,7 +424,7 @@ static void snd_pcm_substream_proc_sw_params_read(struct snd_info_entry *entry,
 		snd_iprintf(buffer, "closed\n");
 		goto unlock;
 	}
-	if (runtime->status->state == SNDRV_PCM_STATE_OPEN) {
+	if (runtime->state == SNDRV_PCM_STATE_OPEN) {
 		snd_iprintf(buffer, "no setup\n");
 		goto unlock;
 	}
@@ -970,7 +970,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 	init_waitqueue_head(&runtime->sleep);
 	init_waitqueue_head(&runtime->tsleep);
 
-	runtime->status->state = SNDRV_PCM_STATE_OPEN;
+	__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_OPEN);
 	mutex_init(&runtime->buffer_mutex);
 	atomic_set(&runtime->buffer_accessing, 0);
 
@@ -1112,7 +1112,8 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			if (snd_pcm_running(substream))
 				snd_pcm_stop(substream, SNDRV_PCM_STATE_DISCONNECTED);
 			/* to be sure, set the state unconditionally */
-			substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
+			__snd_pcm_set_state(substream->runtime,
+					    SNDRV_PCM_STATE_DISCONNECTED);
 			wake_up(&substream->runtime->sleep);
 			wake_up(&substream->runtime->tsleep);
 		}

sound/core/pcm_compat.c

@@ -295,7 +295,7 @@ static int snd_pcm_ioctl_xferi_compat(struct snd_pcm_substream *substream,
 		return -ENOTTY;
 	if (substream->stream != dir)
 		return -EINVAL;
-	if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN)
+	if (substream->runtime->state == SNDRV_PCM_STATE_OPEN)
 		return -EBADFD;
 
 	if (get_user(buf, &data32->buf) ||
@@ -341,7 +341,7 @@ static int snd_pcm_ioctl_xfern_compat(struct snd_pcm_substream *substream,
 		return -ENOTTY;
 	if (substream->stream != dir)
 		return -EINVAL;
-	if (substream->runtime->status->state == SNDRV_PCM_STATE_OPEN)
+	if (substream->runtime->state == SNDRV_PCM_STATE_OPEN)
 		return -EBADFD;
 
 	ch = substream->runtime->channels;

sound/core/pcm_lib.c

@@ -186,7 +186,7 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream,
 	avail = snd_pcm_avail(substream);
 	if (avail > runtime->avail_max)
 		runtime->avail_max = avail;
-	if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
+	if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
 		if (avail >= runtime->buffer_size) {
 			snd_pcm_drain_done(substream);
 			return -EPIPE;
@@ -1911,7 +1911,7 @@ static int wait_for_avail(struct snd_pcm_substream *substream,
 
 		snd_pcm_stream_lock_irq(substream);
 		set_current_state(TASK_INTERRUPTIBLE);
-		switch (runtime->status->state) {
+		switch (runtime->state) {
 		case SNDRV_PCM_STATE_SUSPENDED:
 			err = -ESTRPIPE;
 			goto _endloop;
@@ -2099,14 +2099,14 @@ static int pcm_sanity_check(struct snd_pcm_substream *substream)
 	runtime = substream->runtime;
 	if (snd_BUG_ON(!substream->ops->copy_user && !runtime->dma_area))
 		return -EINVAL;
-	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
+	if (runtime->state == SNDRV_PCM_STATE_OPEN)
 		return -EBADFD;
 	return 0;
 }
 
 static int pcm_accessible_state(struct snd_pcm_runtime *runtime)
 {
-	switch (runtime->status->state) {
+	switch (runtime->state) {
 	case SNDRV_PCM_STATE_PREPARED:
 	case SNDRV_PCM_STATE_RUNNING:
 	case SNDRV_PCM_STATE_PAUSED:
@@ -2225,7 +2225,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
 		goto _end_unlock;
 
 	runtime->twake = runtime->control->avail_min ? : 1;
-	if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
+	if (runtime->state == SNDRV_PCM_STATE_RUNNING)
 		snd_pcm_update_hw_ptr(substream);
 
 	/*
@@ -2233,7 +2233,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
 	 * thread may start capture
 	 */
 	if (!is_playback &&
-	    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&
+	    runtime->state == SNDRV_PCM_STATE_PREPARED &&
 	    size >= runtime->start_threshold) {
 		err = snd_pcm_start(substream);
 		if (err < 0)
@@ -2247,7 +2247,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
 		snd_pcm_uframes_t cont;
 		if (!avail) {
 			if (!is_playback &&
-			    runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
+			    runtime->state == SNDRV_PCM_STATE_DRAINING) {
 				snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
 				goto _end_unlock;
 			}
@@ -2303,7 +2303,7 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
 		xfer += frames;
 		avail -= frames;
 		if (is_playback &&
-		    runtime->status->state == SNDRV_PCM_STATE_PREPARED &&
+		    runtime->state == SNDRV_PCM_STATE_PREPARED &&
 		    snd_pcm_playback_hw_avail(runtime) >= (snd_pcm_sframes_t)runtime->start_threshold) {
 			err = snd_pcm_start(substream);
 			if (err < 0)