From: Ziyi Guo <[email protected]> [ Upstream commit 84faa91585fa22a161763f2fe8f84a602a196c87 ]
imx_rpmsg_probe() calls snd_soc_find_dai() without holding client_mutex. However, snd_soc_find_dai() has lockdep_assert_held(&client_mutex) indicating callers must hold this lock, as the function iterates over the global component list. All other callers of snd_soc_find_dai() either hold client_mutex via the snd_soc_bind_card() path or use the snd_soc_find_dai_with_mutex() wrapper. Use snd_soc_find_dai_with_mutex() instead to fix the missing lock protection. Signed-off-by: Ziyi Guo <[email protected]> Reviewed-by: Frank Li <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Mark Brown <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- LLM Generated explanations, may be completely bogus: The wrapper was added in 2020, so it exists in all currently maintained stable trees (5.10+, 5.15+, 6.1+, 6.6+, 6.12+). This confirms the fix will apply cleanly to all relevant stable branches. ### User Impact - Without this fix, users with i.MX RPMSG sound cards will hit **lockdep warnings** during probe when `CONFIG_PROVE_LOCKING` is enabled - More seriously, without the lock, there is a real (though perhaps rare) **race condition** where concurrent component registration/deregistration during probe could corrupt the component list, leading to crashes or undefined behavior - The i.MX RPMSG audio is used on NXP i.MX SoC platforms, which are widely deployed in embedded systems ### Stability Indicators - **Reviewed-by: Frank Li** (NXP maintainer) - indicates domain expertise review - **Applied by Mark Brown** (ASoC subsystem maintainer) - indicates acceptance by the subsystem maintainer - Single-line change with zero risk of regression ### Summary This is a textbook stable backport candidate: 1. **Fixes a real bug**: Missing lock protection for a global list traversal (race condition + lockdep warning) 2. **Obviously correct**: Uses the existing mutex wrapper that all other callers use 3. **Small and surgical**: Single line change 4. **No new features**: Just corrects locking 5. **Low risk**: The wrapper function has existed since 2020 and is well-tested 6. **No dependencies**: Self-contained fix **YES** sound/soc/fsl/imx-rpmsg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/soc/fsl/imx-rpmsg.c b/sound/soc/fsl/imx-rpmsg.c index 53f04d1f32806..76a8e68c1b620 100644 --- a/sound/soc/fsl/imx-rpmsg.c +++ b/sound/soc/fsl/imx-rpmsg.c @@ -145,7 +145,7 @@ static int imx_rpmsg_probe(struct platform_device *pdev) data->dai.ignore_pmdown_time = 1; data->dai.cpus->dai_name = pdev->dev.platform_data; - cpu_dai = snd_soc_find_dai(data->dai.cpus); + cpu_dai = snd_soc_find_dai_with_mutex(data->dai.cpus); if (!cpu_dai) { ret = -EPROBE_DEFER; goto fail; -- 2.51.0
