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.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 18 insertions, 2 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 8c48a5bce88c..7b1a022910e8 100644
--- a/include/sound/pcm.h
+++ b/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 */
@@ -678,12 +680,26 @@ 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
  * @size: size in bytes