From 199db9fa4ae920159d0e54c29b1f739ffda20003 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 13 Nov 2024 12:10:38 +0100
Subject: [PATCH] ALSA: caiaq: Use snd_card_free_when_closed() at disconnection

[ Upstream commit b04dcbb7f7b1908806b7dc22671cdbe78ff2b82c ]

The USB disconnect callback is supposed to be short and not too-long
waiting.  OTOH, the current code uses snd_card_free() at
disconnection, but this waits for the close of all used fds, hence it
can take long.  It eventually blocks the upper layer USB ioctls, which
may trigger a soft lockup.

An easy workaround is to replace snd_card_free() with
snd_card_free_when_closed().  This variant returns immediately while
the release of resources is done asynchronously by the card device
release at the last close.

This patch also splits the code to the disconnect and the free phases;
the former is called immediately at the USB disconnect callback while
the latter is called from the card destructor.

Fixes: 523f1dce3743 ("[ALSA] Add Native Instrument usb audio device support")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20241113111042.15058-5-tiwai@suse.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/usb/caiaq/audio.c  | 10 ++++++++--
 sound/usb/caiaq/audio.h  |  1 +
 sound/usb/caiaq/device.c | 19 +++++++++++++++----
 sound/usb/caiaq/input.c  | 12 +++++++++---
 sound/usb/caiaq/input.h  |  1 +
 5 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/sound/usb/caiaq/audio.c b/sound/usb/caiaq/audio.c
index 3b6bb2cbe..1308415b5 100755
--- a/sound/usb/caiaq/audio.c
+++ b/sound/usb/caiaq/audio.c
@@ -869,14 +869,20 @@ int snd_usb_caiaq_audio_init(struct snd_usb_caiaqdev *cdev)
 	return 0;
 }
 
-void snd_usb_caiaq_audio_free(struct snd_usb_caiaqdev *cdev)
+void snd_usb_caiaq_audio_disconnect(struct snd_usb_caiaqdev *cdev)
 {
 	struct device *dev = caiaqdev_to_dev(cdev);
 
 	dev_dbg(dev, "%s(%p)\n", __func__, cdev);
 	stream_stop(cdev);
+}
+
+void snd_usb_caiaq_audio_free(struct snd_usb_caiaqdev *cdev)
+{
+	struct device *dev = caiaqdev_to_dev(cdev);
+
+	dev_dbg(dev, "%s(%p)\n", __func__, cdev);
 	free_urbs(cdev->data_urbs_in);
 	free_urbs(cdev->data_urbs_out);
 	kfree(cdev->data_cb_info);
 }
-
diff --git a/sound/usb/caiaq/audio.h b/sound/usb/caiaq/audio.h
index 869bf6264..07f5d0644 100755
--- a/sound/usb/caiaq/audio.h
+++ b/sound/usb/caiaq/audio.h
@@ -3,6 +3,7 @@
 #define CAIAQ_AUDIO_H
 
 int snd_usb_caiaq_audio_init(struct snd_usb_caiaqdev *cdev);
+void snd_usb_caiaq_audio_disconnect(struct snd_usb_caiaqdev *cdev);
 void snd_usb_caiaq_audio_free(struct snd_usb_caiaqdev *cdev);
 
 #endif /* CAIAQ_AUDIO_H */
diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
index 2af3b7eb0..482d4915e 100755
--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -390,6 +390,17 @@ static void setup_card(struct snd_usb_caiaqdev *cdev)
 		dev_err(dev, "Unable to set up control system (ret=%d)\n", ret);
 }
 
+static void card_free(struct snd_card *card)
+{
+	struct snd_usb_caiaqdev *cdev = caiaqdev(card);
+
+#ifdef CONFIG_SND_USB_CAIAQ_INPUT
+	snd_usb_caiaq_input_free(cdev);
+#endif
+	snd_usb_caiaq_audio_free(cdev);
+	usb_reset_device(cdev->chip.dev);
+}
+
 static int create_card(struct usb_device *usb_dev,
 		       struct usb_interface *intf,
 		       struct snd_card **cardp)
@@ -503,6 +514,7 @@ static int init_card(struct snd_usb_caiaqdev *cdev)
 		       cdev->vendor_name, cdev->product_name, usbpath);
 
 	setup_card(cdev);
+	card->private_free = card_free;
 	return 0;
 
  err_kill_urb:
@@ -548,15 +560,14 @@ static void snd_disconnect(struct usb_interface *intf)
 	snd_card_disconnect(card);
 
 #ifdef CONFIG_SND_USB_CAIAQ_INPUT
-	snd_usb_caiaq_input_free(cdev);
+	snd_usb_caiaq_input_disconnect(cdev);
 #endif
-	snd_usb_caiaq_audio_free(cdev);
+	snd_usb_caiaq_audio_disconnect(cdev);
 
 	usb_kill_urb(&cdev->ep1_in_urb);
 	usb_kill_urb(&cdev->midi_out_urb);
 
-	snd_card_free(card);
-	usb_reset_device(interface_to_usbdev(intf));
+	snd_card_free_when_closed(card);
 }
 
 
diff --git a/sound/usb/caiaq/input.c b/sound/usb/caiaq/input.c
index 84f26dce7..a9130891b 100755
--- a/sound/usb/caiaq/input.c
+++ b/sound/usb/caiaq/input.c
@@ -829,15 +829,21 @@ exit_free_idev:
 	return ret;
 }
 
-void snd_usb_caiaq_input_free(struct snd_usb_caiaqdev *cdev)
+void snd_usb_caiaq_input_disconnect(struct snd_usb_caiaqdev *cdev)
 {
 	if (!cdev || !cdev->input_dev)
 		return;
 
 	usb_kill_urb(cdev->ep4_in_urb);
+	input_unregister_device(cdev->input_dev);
+}
+
+void snd_usb_caiaq_input_free(struct snd_usb_caiaqdev *cdev)
+{
+	if (!cdev || !cdev->input_dev)
+		return;
+
 	usb_free_urb(cdev->ep4_in_urb);
 	cdev->ep4_in_urb = NULL;
-
-	input_unregister_device(cdev->input_dev);
 	cdev->input_dev = NULL;
 }
diff --git a/sound/usb/caiaq/input.h b/sound/usb/caiaq/input.h
index c42891e7b..fbe267f85 100755
--- a/sound/usb/caiaq/input.h
+++ b/sound/usb/caiaq/input.h
@@ -4,6 +4,7 @@
 
 void snd_usb_caiaq_input_dispatch(struct snd_usb_caiaqdev *cdev, char *buf, unsigned int len);
 int snd_usb_caiaq_input_init(struct snd_usb_caiaqdev *cdev);
+void snd_usb_caiaq_input_disconnect(struct snd_usb_caiaqdev *cdev);
 void snd_usb_caiaq_input_free(struct snd_usb_caiaqdev *cdev);
 
 #endif