sound: rawmidi: record a substream's owner process

Record the pid of the task that opened a RawMIDI substream.

Signed-off-by: Clemens Ladisch <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

include/sound/rawmidi.h

···
 struct snd_rawmidi;
 struct snd_rawmidi_substream;
 struct snd_seq_port_info;
+struct pid;
 
 struct snd_rawmidi_ops {
 	int (*open) (struct snd_rawmidi_substream * substream);
···
 	struct snd_rawmidi_str *pstr;
 	char name[32];
 	struct snd_rawmidi_runtime *runtime;
+	struct pid *pid;
 	/* hardware layer */
 	struct snd_rawmidi_ops *ops;
 };

sound/core/rawmidi.c

···
 		substream->active_sensing = 0;
 		if (mode & SNDRV_RAWMIDI_LFLG_APPEND)
 			substream->append = 1;
+		substream->pid = get_pid(task_pid(current));
 		rmidi->streams[substream->stream].substream_opened++;
 	}
 	substream->use_count++;
···
 	snd_rawmidi_runtime_free(substream);
 	substream->opened = 0;
 	substream->append = 0;
+	put_pid(substream->pid);
+	substream->pid = NULL;
 	rmidi->streams[substream->stream].substream_opened--;
 }
 
···
 				    substream->number,
 				    (unsigned long) substream->bytes);
 			if (substream->opened) {
+				snd_iprintf(buffer,
+				    "  Owner PID    : %d\n",
+				    pid_vnr(substream->pid));
 				runtime = substream->runtime;
 				snd_iprintf(buffer,
 				    "  Mode         : %s\n"
···
 				    substream->number,
 				    (unsigned long) substream->bytes);
 			if (substream->opened) {
+				snd_iprintf(buffer,
+					    "  Owner PID    : %d\n",
+					    pid_vnr(substream->pid));
 				runtime = substream->runtime;
 				snd_iprintf(buffer,
 					    "  Buffer size  : %lu\n"