The SND_SOC_DAPM_PRE_PMU case would call startup()/hw_params() that might access substream->runtime through other functions.

For example:

Unable to handle kernel NULL pointer dereference at virtual address [....] PC is at snd_pcm_hw_rule_add+0x24/0x1b0 LR is at snd_pcm_hw_constraint_list+0x20/0x28 [....] Process arecord (pid: 424, stack limit = 0xffffffc1ecaf0020) Call trace: [<ffffffc00086be68>] snd_pcm_hw_rule_add+0x24/0x1b0 [<ffffffc00086c014>] snd_pcm_hw_constraint_list+0x20/0x28 [<ffffffc0008b47a4>] cs53l30_pcm_startup+0x24/0x30 [<ffffffc0008a6260>] snd_soc_dai_link_event+0x290/0x354 [<ffffffc0008a7528>] dapm_seq_check_event.isra.31+0x134/0x2c8 [<ffffffc0008a7768>] dapm_seq_run_coalesced+0x94/0x1c8 [<ffffffc0008a7940>] dapm_seq_run+0xa4/0x404 [<ffffffc0008a8bac>] dapm_power_widgets+0x524/0x984 [<ffffffc0008ab1c4>] snd_soc_dapm_stream_event+0x8c/0xa8 [<ffffffc0008ac7f4>] soc_pcm_prepare+0x10c/0x1ec [<ffffffc000865b9c>] snd_pcm_do_prepare+0x1c/0x38 [<ffffffc000865600>] snd_pcm_action_single+0x40/0x88 [<ffffffc0008656b8>] snd_pcm_action_nonatomic+0x70/0x90 [<ffffffc000868d28>] snd_pcm_common_ioctl1+0xb6c/0xdd8 [<ffffffc000869508>] snd_pcm_capture_ioctl1+0x200/0x334 [<ffffffc00086a084>] snd_pcm_ioctl_compat+0x648/0x95c [<ffffffc0001ff4b4>] compat_SyS_ioctl+0xac/0xfc4 [<ffffffc000084cf0>] el0_svc_naked+0x24/0x28 ---[ end trace 0dc4f99c2759c35c ]---

So this patch adds a dummy runtime for the original dummy substream to merely avoid the NULL pointer access.

Signed-off-by: Nicolin Chen nicoleotsuka@gmail.com --- sound/soc/soc-dapm.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index 8698c26..eed15ca 100644 --- a/sound/soc/soc-dapm.c +++ b/sound/soc/soc-dapm.c @@ -3493,6 +3493,7 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w, const struct snd_soc_pcm_stream *config = w->params + w->params_select; struct snd_pcm_substream substream; struct snd_pcm_hw_params *params = NULL; + struct snd_pcm_runtime runtime; u64 fmt; int ret;

@@ -3540,6 +3541,8 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w, = config->channels_max;

memset(&substream, 0, sizeof(substream)); + memset(&runtime, 0, sizeof(runtime)); + substream.runtime = &runtime;

switch (event) { case SND_SOC_DAPM_PRE_PMU: