linux-kernel - [PATCH v2] ASoC: fsl_xcvr: Revert fix missing lock in fsl_xcvr_mode

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Message-Id: <20260210185714.556385-1-n7l8m4@u.northwestern.edu>
Date: Tue, 10 Feb 2026 18:57:14 +0000
From: Ziyi Guo <n7l8m4@...orthwestern.edu>
To: Mark Brown <broonie@...nel.org>,
	Alexander Stein <alexander.stein@...tq-group.com>
Cc: Shengjiu Wang <shengjiu.wang@...il.com>,
	Xiubo Li <Xiubo.Lee@...il.com>,
	Fabio Estevam <festevam@...il.com>,
	Nicolin Chen <nicoleotsuka@...il.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	linux-sound@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	Ziyi Guo <n7l8m4@...orthwestern.edu>
Subject: [PATCH v2] ASoC: fsl_xcvr: Revert fix missing lock in fsl_xcvr_mode_put()

This reverts commit f51424872760 ("ASoC: fsl_xcvr: fix missing lock in fsl_xcvr_mode_put()").

The original patch attempted to acquire the card->controls_rwsem lock in
fsl_xcvr_mode_put(). However, this function is called from the upper ALSA
core function snd_ctl_elem_write(), which already holds the write lock on
controls_rwsem for the whole put operation. So there is no need to simply
hold the lock for fsl_xcvr_activate_ctl() again.

Acquiring the read lock while holding the write lock in the same thread
results in a deadlock and a hung task, as reported by Alexander Stein.

Reported-by: Alexander Stein <alexander.stein@...tq-group.com>
Closes: https://lore.kernel.org/linux-sound/5056506.GXAFRqVoOG@steina-w/
Signed-off-by: Ziyi Guo <n7l8m4@...orthwestern.edu>
---
v2:
 - Refactor subject line style
 - Include human readable descriptions
 - Fix the sha1 information for sound/soc/fsl/fsl_xcvr.c

 sound/soc/fsl/fsl_xcvr.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/sound/soc/fsl/fsl_xcvr.c b/sound/soc/fsl/fsl_xcvr.c
index 5de93f458b56..a268fb81a2f8 100644
--- a/sound/soc/fsl/fsl_xcvr.c
+++ b/sound/soc/fsl/fsl_xcvr.c
@@ -223,13 +223,10 @@ static int fsl_xcvr_mode_put(struct snd_kcontrol *kcontrol,
 
 	xcvr->mode = snd_soc_enum_item_to_val(e, item[0]);
 
-	down_read(&card->snd_card->controls_rwsem);
 	fsl_xcvr_activate_ctl(dai, fsl_xcvr_arc_mode_kctl.name,
 			      (xcvr->mode == FSL_XCVR_MODE_ARC));
 	fsl_xcvr_activate_ctl(dai, fsl_xcvr_earc_capds_kctl.name,
 			      (xcvr->mode == FSL_XCVR_MODE_EARC));
-	up_read(&card->snd_card->controls_rwsem);
-
 	/* Allow playback for SPDIF only */
 	rtd = snd_soc_get_pcm_runtime(card, card->dai_link);
 	rtd->pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream_count =
-- 
2.34.1