linux-kernel - [PATCH v4] ALSA: usb-audio: qcom: Adjust mutex unlock order

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Message-ID: <20250721114554.1666104-1-karanja99erick@gmail.com>
Date: Mon, 21 Jul 2025 14:45:53 +0300
From: Erick Karanja <karanja99erick@...il.com>
To: perex@...ex.cz,
	tiwai@...e.com
Cc: linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Erick Karanja <karanja99erick@...il.com>
Subject: [PATCH v4] ALSA: usb-audio: qcom: Adjust mutex unlock order

The mutexes qdev_mutex and chip->mutex are acquired in that order
throughout the driver. To preserve proper lock hierarchy and avoid
potential deadlocks, they must be released in the reverse
order of acquisition.

This change reorders the unlock sequence to first release chip->mutex
followed by qdev_mutex, ensuring consistency with the locking pattern.

Fixes: 326bbc348298a ("ALSA: usb-audio: qcom: Introduce QC USB
                      SND offloading support")

changes since v3:
 - Add the correct fixes tag.

Signed-off-by: Erick Karanja <karanja99erick@...il.com>
---
 sound/usb/qcom/qc_audio_offload.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c
index 3543b5a53592..711f5612a83a 100644
--- a/sound/usb/qcom/qc_audio_offload.c
+++ b/sound/usb/qcom/qc_audio_offload.c
@@ -825,8 +825,8 @@ static int uaudio_sideband_notifier(struct usb_interface *intf,
 		}
 	}
 
-	mutex_unlock(&qdev_mutex);
 	mutex_unlock(&chip->mutex);
+	mutex_unlock(&qdev_mutex);
 
 	return 0;
 }
@@ -1865,8 +1865,8 @@ static void qc_usb_audio_offload_disconnect(struct snd_usb_audio *chip)
 
 	/* Device has already been cleaned up, or never populated */
 	if (!dev->chip) {
-		mutex_unlock(&qdev_mutex);
 		mutex_unlock(&chip->mutex);
+		mutex_unlock(&qdev_mutex);
 		return;
 	}
 
@@ -1921,8 +1921,8 @@ static void qc_usb_audio_offload_suspend(struct usb_interface *intf,
 
 	uaudio_send_disconnect_ind(chip);
 
+        mutex_unlock(&chip->mutex);
 	mutex_unlock(&qdev_mutex);
-	mutex_unlock(&chip->mutex);
 }
 
 static struct snd_usb_platform_ops offload_ops = {
-- 
2.43.0