ALSA: rawmidi: Skip UMP devices at SNDRV_CTL_IOCTL_RAWMIDI_NEXT_DEVICE

Applications may look for rawmidi devices with the ioctl
SNDRV_CTL_IOCTL_RAWMIDI_NEXT_DEVICE. Returning a UMP device from this
ioctl may confuse the existing applications that support only the
legacy rawmidi.

This patch changes the code to skip the UMP devices from the lookup
for avoiding the confusion, and introduces a new ioctl to look for the
UMP devices instead.

Along with this change, bump the CTL protocol version to 2.0.9.

Reviewed-by: Jaroslav Kysela <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

include/uapi/sound/asound.h

···
  *                                                                          *
  ****************************************************************************/
 
-#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 8)
+#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 9)
 
 struct snd_ctl_card_info {
 	int card;			/* card number */
···
 #define SNDRV_CTL_IOCTL_RAWMIDI_NEXT_DEVICE _IOWR('U', 0x40, int)
 #define SNDRV_CTL_IOCTL_RAWMIDI_INFO	_IOWR('U', 0x41, struct snd_rawmidi_info)
 #define SNDRV_CTL_IOCTL_RAWMIDI_PREFER_SUBDEVICE _IOW('U', 0x42, int)
+#define SNDRV_CTL_IOCTL_UMP_NEXT_DEVICE	_IOWR('U', 0x43, int)
 #define SNDRV_CTL_IOCTL_POWER		_IOWR('U', 0xd0, int)
 #define SNDRV_CTL_IOCTL_POWER_STATE	_IOR('U', 0xd1, int)
 

sound/core/rawmidi.c

···
 	return -ENOTTY;
 }
 
+/* ioctl to find the next device; either legacy or UMP depending on @find_ump */
+static int snd_rawmidi_next_device(struct snd_card *card, int __user *argp,
+				   bool find_ump)
+
+{
+	struct snd_rawmidi *rmidi;
+	int device;
+	bool is_ump;
+
+	if (get_user(device, argp))
+		return -EFAULT;
+	if (device >= SNDRV_RAWMIDI_DEVICES) /* next device is -1 */
+		device = SNDRV_RAWMIDI_DEVICES - 1;
+	mutex_lock(&register_mutex);
+	device = device < 0 ? 0 : device + 1;
+	for (; device < SNDRV_RAWMIDI_DEVICES; device++) {
+		rmidi = snd_rawmidi_search(card, device);
+		if (!rmidi)
+			continue;
+		is_ump = rawmidi_is_ump(rmidi);
+		if (find_ump == is_ump)
+			break;
+	}
+	if (device == SNDRV_RAWMIDI_DEVICES)
+		device = -1;
+	mutex_unlock(&register_mutex);
+	if (put_user(device, argp))
+		return -EFAULT;
+	return 0;
+}
+
 static int snd_rawmidi_control_ioctl(struct snd_card *card,
 				     struct snd_ctl_file *control,
 				     unsigned int cmd,
···
 
 	switch (cmd) {
 	case SNDRV_CTL_IOCTL_RAWMIDI_NEXT_DEVICE:
-	{
-		int device;
-
-		if (get_user(device, (int __user *)argp))
-			return -EFAULT;
-		if (device >= SNDRV_RAWMIDI_DEVICES) /* next device is -1 */
-			device = SNDRV_RAWMIDI_DEVICES - 1;
-		mutex_lock(&register_mutex);
-		device = device < 0 ? 0 : device + 1;
-		while (device < SNDRV_RAWMIDI_DEVICES) {
-			if (snd_rawmidi_search(card, device))
-				break;
-			device++;
-		}
-		if (device == SNDRV_RAWMIDI_DEVICES)
-			device = -1;
-		mutex_unlock(&register_mutex);
-		if (put_user(device, (int __user *)argp))
-			return -EFAULT;
-		return 0;
-	}
+		return snd_rawmidi_next_device(card, argp, false);
+#if IS_ENABLED(CONFIG_SND_UMP)
+	case SNDRV_CTL_IOCTL_UMP_NEXT_DEVICE:
+		return snd_rawmidi_next_device(card, argp, true);
+#endif
 	case SNDRV_CTL_IOCTL_RAWMIDI_PREFER_SUBDEVICE:
 	{
 		int val;