queue-5.10/media-go7007-defer-the-alsa-v4l2-put-until-card-release.patch

From 1bd456afeb8a515137e567967069fce6f8fcd23e Mon Sep 17 00:00:00 2001
From: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Date: Mon, 6 Jul 2026 16:50:15 -0400
Subject: media: go7007: defer the ALSA v4l2 put until card release

From: Shuangpeng Bai <shuangpeng.kernel@gmail.com>

commit 1bd456afeb8a515137e567967069fce6f8fcd23e upstream.

go7007_snd_init() already takes a v4l2_device reference for the ALSA
side, but go7007_snd_remove() drops it immediately after calling
snd_card_free_when_closed().

That is too early when a userspace process still has the capture PCM open.
The ALSA card and its PCM callbacks remain alive until the last file is
closed, so the release path can still reach struct go7007 through
pcm->private_data and call go7007_snd_hw_free() after the V4L2 release path
has freed the object.

Move the matching v4l2_device_put() to the ALSA card private_free callback
so the existing ALSA reference covers the whole deferred card lifetime.

Closes: https://lore.kernel.org/r/178144969601.60470.6005237146425573205@gmail.com
Fixes: d5d3a7cc127d ("[media] go7007: fix unregister/disconnect handling")
Cc: stable@vger.kernel.org
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/usb/go7007/snd-go7007.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/media/usb/go7007/snd-go7007.c
+++ b/drivers/media/usb/go7007/snd-go7007.c
@@ -195,6 +195,13 @@ static struct snd_device_ops go7007_snd_
 	.dev_free	= go7007_snd_free,
 };
 
+static void go7007_snd_card_free(struct snd_card *card)
+{
+	struct go7007 *go = card->private_data;
+
+	v4l2_device_put(&go->v4l2_dev);
+}
+
 int go7007_snd_init(struct go7007 *go)
 {
 	static int dev;
@@ -245,6 +252,8 @@ int go7007_snd_init(struct go7007 *go)
 	gosnd->substream = NULL;
 	go->snd_context = gosnd;
 	v4l2_device_get(&go->v4l2_dev);
+	gosnd->card->private_data = go;
+	gosnd->card->private_free = go7007_snd_card_free;
 	++dev;
 
 	return 0;
@@ -263,7 +272,6 @@ int go7007_snd_remove(struct go7007 *go)
 
 	snd_card_disconnect(gosnd->card);
 	snd_card_free_when_closed(gosnd->card);
-	v4l2_device_put(&go->v4l2_dev);
 	return 0;
 }
 EXPORT_SYMBOL(go7007_snd_remove);