Hi,
Am Montag, 2. Februar 2026, 18:41:12 CET schrieb Ziyi Guo:
> fsl_xcvr_activate_ctl() has
> lockdep_assert_held(&card->snd_card->controls_rwsem),
> but fsl_xcvr_mode_put() calls it without acquiring this lock.
>
> Other callers of fsl_xcvr_activate_ctl() in fsl_xcvr_startup() and
> fsl_xcvr_shutdown() properly acquire the lock with down_read()/up_read().
>
> Add the missing down_read()/up_read() calls around fsl_xcvr_activate_ctl()
> in fsl_xcvr_mode_put() to fix the lockdep assertion and prevent potential
> race conditions when multiple userspace threads access the control.
>
> Signed-off-by: Ziyi Guo <[email protected]>
> ---
> sound/soc/fsl/fsl_xcvr.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/sound/soc/fsl/fsl_xcvr.c b/sound/soc/fsl/fsl_xcvr.c
> index a268fb81a2f8..0b9dd64b9a82 100644
> --- a/sound/soc/fsl/fsl_xcvr.c
> +++ b/sound/soc/fsl/fsl_xcvr.c
> @@ -223,10 +223,13 @@ 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);
This lock causes a blocked task on my TQMa8MPxL based board:
INFO: task alsactl:1969 blocked for more than 120 seconds.
Tainted: G W 6.19.0-next-20260209+ #3331
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:alsactl state:D stack:0 pid:1969 tgid:1969 ppid:1
task_flags:0x400100 flags:0x00000a01
Call trace:
__switch_to+0xdc/0x120 (T)
__schedule+0x258/0x790
schedule+0x30/0xb0
schedule_preempt_disabled+0x20/0x40
rwsem_down_read_slowpath+0x214/0x68c
down_read+0xb0/0xb8
fsl_xcvr_mode_put+0x4c/0xc0 [snd_soc_fsl_xcvr
ac1b31380c6a6ea0d613bd5f78489e314a40f91f]
snd_ctl_elem_write+0xdc/0x180 [snd 852e63996474051c57bcd1a86ebfd81083073853]
snd_ctl_ioctl+0x7a4/0xaec [snd 852e63996474051c57bcd1a86ebfd81083073853]
__arm64_sys_ioctl+0x9c/0xe4
invoke_syscall.constprop.0+0x58/0xcc
el0_svc_common.constprop.0+0xac/0xd4
do_el0_svc+0x18/0x20
el0_svc+0x24/0xa0
el0t_64_sync_handler+0x98/0xdc
el0t_64_sync+0x154/0x158
INFO: task alsactl:1969 <reader> blocked on an rw-semaphore likely owned by
task alsactl:1969 <writer>
Best regards,
Alexander
> 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 =
>
--
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