FAILED: patch "[PATCH] ALSA: usb-audio: Protect Roland control activation" failed to apply to 6.18-stable tree

FAILED: patch "[PATCH] ALSA: usb-audio: Protect Roland control activation" failed to apply to 6.18-stable tree

[Sasha Levin]

The patch below does not apply to the 6.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 19b42c1fff7f220a6346c614d79ce1bda6d95b40
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107050744-failed-6.18-19b42c1fff7f@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 19b42c1fff7f220a6346c614d79ce1bda6d95b40 Mon Sep 17 00:00:00 2001
From: Runyu Xiao <runyu.xiao@seu.edu.cn>
Date: Tue, 29 Sep 2026 22:17:26 +0800
Subject: [PATCH] ALSA: usb-audio: Protect Roland control activation

The USB MIDI driver changes the Roland MIDI Input Mode control's access
flags directly from the rawmidi open and close paths.  These changes are
not protected by the ALSA control core and the corresponding notifications
can race with control access.

Use snd_ctl_activate_id() so that the control core updates the access flags
and sends the notification under its lock.  Release the USB MIDI mutex
before calling it because the control write path holds controls_rwsem while
roland_load_put() takes the USB MIDI mutex.

Keep the state transition and alternate-setting change under the USB MIDI
mutex; rawmidi's open mutex serializes the enclosing open and close paths.

Fixes: 96f61d9ade82 ("sound: usb-audio: allow switching altsetting on Roland USB MIDI devices")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Link: https://patch.msgid.link/20260929141726.2166899-1-runyu.xiao@seu.edu.cn
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/usb/midi.c | 53 ++++++++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 0480a9b89e8f3..e3d1575540613 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1150,41 +1150,42 @@ static int substream_open(struct snd_rawmidi_substream *substream, int dir,
 			  int open)
 {
 	struct snd_usb_midi *umidi = substream->rmidi->private_data;
-	struct snd_kcontrol *ctl;
+	struct snd_ctl_elem_id ctl_id;
+	bool activate_ctl = false;
+	bool active;
 
 	guard(rwsem_read)(&umidi->disc_rwsem);
 	if (umidi->disconnected)
 		return open ? -ENODEV : 0;
 
-	guard(mutex)(&umidi->mutex);
-	if (open) {
-		if (!umidi->opened[0] && !umidi->opened[1]) {
-			if (umidi->roland_load_ctl) {
-				ctl = umidi->roland_load_ctl;
-				ctl->vd[0].access |=
-					SNDRV_CTL_ELEM_ACCESS_INACTIVE;
-				snd_ctl_notify(umidi->card,
-				       SNDRV_CTL_EVENT_MASK_INFO, &ctl->id);
-				update_roland_altsetting(umidi);
+	scoped_guard(mutex, &umidi->mutex) {
+		if (open) {
+			if (!umidi->opened[0] && !umidi->opened[1]) {
+				if (umidi->roland_load_ctl) {
+					ctl_id = umidi->roland_load_ctl->id;
+					activate_ctl = true;
+					active = false;
+					update_roland_altsetting(umidi);
+				}
 			}
-		}
-		umidi->opened[dir]++;
-		if (umidi->opened[1])
-			snd_usbmidi_input_start(&umidi->list);
-	} else {
-		umidi->opened[dir]--;
-		if (!umidi->opened[1] && !umidi->keep_input_running)
-			snd_usbmidi_input_stop(&umidi->list);
-		if (!umidi->opened[0] && !umidi->opened[1]) {
-			if (umidi->roland_load_ctl) {
-				ctl = umidi->roland_load_ctl;
-				ctl->vd[0].access &=
-					~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
-				snd_ctl_notify(umidi->card,
-				       SNDRV_CTL_EVENT_MASK_INFO, &ctl->id);
+			umidi->opened[dir]++;
+			if (umidi->opened[1])
+				snd_usbmidi_input_start(&umidi->list);
+		} else {
+			umidi->opened[dir]--;
+			if (!umidi->opened[1] && !umidi->keep_input_running)
+				snd_usbmidi_input_stop(&umidi->list);
+			if (!umidi->opened[0] && !umidi->opened[1]) {
+				if (umidi->roland_load_ctl) {
+					ctl_id = umidi->roland_load_ctl->id;
+					activate_ctl = true;
+					active = true;
+				}
 			}
 		}
 	}
+	if (activate_ctl)
+		snd_ctl_activate_id(umidi->card, &ctl_id, active);
 	return 0;
 }
 
-- 
2.53.0

[PATCH 6.18.y 1/2] ALSA: usb-audio: keep MIDI input running for Roland TD-11

[Sasha Levin]

From: Nicholas Hobson <nicholas.hobson@outlook.com>

[ Upstream commit 2e4c9ab2574eeaa7b893c7d35b4a9f60fd681ddd ]

The TD-11 hands MIDI handling off to the host once connected via
USB. If no MIDI input port is opened on the host, the device itself
becomes unusable as a standalone instrument until its input is
serviced, independent of anything happening on the computer.

Add a per-device keep_input_running flag, set for the TD-11 in
snd_usbmidi_detect_roland(), and check it alongside the existing
opened[1] check in snd_usbmidi_input_start()/snd_usbmidi_input_stop()
so that input is started at device creation and never stopped for
these devices, regardless of whether a client has the input port
open.

Signed-off-by: Nicholas Hobson <nicholas.hobson@outlook.com>
Link: https://patch.msgid.link/MN2PR15MB3472557AF39DC3A4CA9E753FF8BD2@MN2PR15MB3472.namprd15.prod.outlook.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Stable-dep-of: 19b42c1fff7f ("ALSA: usb-audio: Protect Roland control activation")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/midi.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 787956252e800..30d0684920319 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -113,6 +113,7 @@ struct snd_usb_midi {
 	unsigned int opened[2];
 	unsigned char disconnected;
 	unsigned char input_running;
+	unsigned char keep_input_running;
 
 	struct snd_kcontrol *roland_load_ctl;
 };
@@ -1168,7 +1169,7 @@ static int substream_open(struct snd_rawmidi_substream *substream, int dir,
 			snd_usbmidi_input_start(&umidi->list);
 	} else {
 		umidi->opened[dir]--;
-		if (!umidi->opened[1])
+		if (!umidi->opened[1] && !umidi->keep_input_running)
 			snd_usbmidi_input_stop(&umidi->list);
 		if (!umidi->opened[0] && !umidi->opened[1]) {
 			if (umidi->roland_load_ctl) {
@@ -2258,6 +2259,10 @@ static int snd_usbmidi_detect_roland(struct snd_usb_midi *umidi,
 	struct usb_host_interface *hostif;
 	u8 *cs_desc;
 
+	/* TD-11 becomes unusable if input isn't serviced continuously */
+	if (umidi->usb_id == USB_ID(0x0582, 0x0151))
+		umidi->keep_input_running = 1;
+
 	intf = umidi->iface;
 	if (!intf)
 		return -ENOENT;
@@ -2465,7 +2470,7 @@ void snd_usbmidi_input_start(struct list_head *p)
 	int i;
 
 	umidi = list_entry(p, struct snd_usb_midi, list);
-	if (umidi->input_running || !umidi->opened[1])
+	if (umidi->input_running || (!umidi->opened[1] && !umidi->keep_input_running))
 		return;
 	for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i)
 		snd_usbmidi_input_start_ep(umidi, umidi->endpoints[i].in);
@@ -2640,6 +2645,10 @@ int __snd_usbmidi_create(struct snd_card *card,
 	if (err < 0)
 		goto exit;
 
+	/* start input for devices that need continuous servicing */
+	if (umidi->keep_input_running)
+		snd_usbmidi_input_start(&umidi->list);
+
 	usb_autopm_get_interface_no_resume(umidi->iface);
 
 	list_add_tail(&umidi->list, midi_list);
-- 
2.53.0

[PATCH 6.18.y 2/2] ALSA: usb-audio: Protect Roland control activation

[Sasha Levin]

From: Runyu Xiao <runyu.xiao@seu.edu.cn>

[ Upstream commit 19b42c1fff7f220a6346c614d79ce1bda6d95b40 ]

The USB MIDI driver changes the Roland MIDI Input Mode control's access
flags directly from the rawmidi open and close paths.  These changes are
not protected by the ALSA control core and the corresponding notifications
can race with control access.

Use snd_ctl_activate_id() so that the control core updates the access flags
and sends the notification under its lock.  Release the USB MIDI mutex
before calling it because the control write path holds controls_rwsem while
roland_load_put() takes the USB MIDI mutex.

Keep the state transition and alternate-setting change under the USB MIDI
mutex; rawmidi's open mutex serializes the enclosing open and close paths.

Fixes: 96f61d9ade82 ("sound: usb-audio: allow switching altsetting on Roland USB MIDI devices")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Link: https://patch.msgid.link/20260929141726.2166899-1-runyu.xiao@seu.edu.cn
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/midi.c | 53 ++++++++++++++++++++++++------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 30d0684920319..c404412ae53b9 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1146,41 +1146,42 @@ static int substream_open(struct snd_rawmidi_substream *substream, int dir,
 			  int open)
 {
 	struct snd_usb_midi *umidi = substream->rmidi->private_data;
-	struct snd_kcontrol *ctl;
+	struct snd_ctl_elem_id ctl_id;
+	bool activate_ctl = false;
+	bool active;
 
 	guard(rwsem_read)(&umidi->disc_rwsem);
 	if (umidi->disconnected)
 		return open ? -ENODEV : 0;
 
-	guard(mutex)(&umidi->mutex);
-	if (open) {
-		if (!umidi->opened[0] && !umidi->opened[1]) {
-			if (umidi->roland_load_ctl) {
-				ctl = umidi->roland_load_ctl;
-				ctl->vd[0].access |=
-					SNDRV_CTL_ELEM_ACCESS_INACTIVE;
-				snd_ctl_notify(umidi->card,
-				       SNDRV_CTL_EVENT_MASK_INFO, &ctl->id);
-				update_roland_altsetting(umidi);
+	scoped_guard(mutex, &umidi->mutex) {
+		if (open) {
+			if (!umidi->opened[0] && !umidi->opened[1]) {
+				if (umidi->roland_load_ctl) {
+					ctl_id = umidi->roland_load_ctl->id;
+					activate_ctl = true;
+					active = false;
+					update_roland_altsetting(umidi);
+				}
 			}
-		}
-		umidi->opened[dir]++;
-		if (umidi->opened[1])
-			snd_usbmidi_input_start(&umidi->list);
-	} else {
-		umidi->opened[dir]--;
-		if (!umidi->opened[1] && !umidi->keep_input_running)
-			snd_usbmidi_input_stop(&umidi->list);
-		if (!umidi->opened[0] && !umidi->opened[1]) {
-			if (umidi->roland_load_ctl) {
-				ctl = umidi->roland_load_ctl;
-				ctl->vd[0].access &=
-					~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
-				snd_ctl_notify(umidi->card,
-				       SNDRV_CTL_EVENT_MASK_INFO, &ctl->id);
+			umidi->opened[dir]++;
+			if (umidi->opened[1])
+				snd_usbmidi_input_start(&umidi->list);
+		} else {
+			umidi->opened[dir]--;
+			if (!umidi->opened[1] && !umidi->keep_input_running)
+				snd_usbmidi_input_stop(&umidi->list);
+			if (!umidi->opened[0] && !umidi->opened[1]) {
+				if (umidi->roland_load_ctl) {
+					ctl_id = umidi->roland_load_ctl->id;
+					activate_ctl = true;
+					active = true;
+				}
 			}
 		}
 	}
+	if (activate_ctl)
+		snd_ctl_activate_id(umidi->card, &ctl_id, active);
 	return 0;
 }
 
-- 
2.53.0