| Message ID | 20191023120114.17445-1-srinivas.kandagatla@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC] ALSA: pcm: fix blocking while loop in snd_pcm_update_hw_ptr0() | expand |
On Wed, 23 Oct 2019 14:01:14 +0200, Srinivas Kandagatla wrote: > > From: Preetam Singh Ranawat <apranawat@codeaurora.org> > > When period interrupts are disabled, while loop in snd_pcm_update_hw_ptr0() > results in the machine locking up if runtime->hw_ptr_buffer_jiffies is 0. > > Validate runtime->hw_ptr_buffer_jiffies value before while loop to avoid > delta check. Although the fix itself is fine, I still wonder how this is triggered. Could you check in what kind of PCM state is it? Basically snd_pcm_update_hw_ptr*() is called only in the running PCM state, and for that, we should have set hw_ptr_buffer_jiffies at snd_pcm_post_start(). It's runtime->hw_ptr_buffer_jiffies = (runtime->buffer_size * HZ) / runtime->rate; So maybe the given buffer size is so small and hw_ptr_buffer_jiffies is really 0? thanks, Takashi > > Signed-off-by: Preetam Singh Ranawat <apranawat@codeaurora.org> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > --- > > This issue was noticed in Android setup from fastcapture path. > > sound/core/pcm_lib.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c > index d80041ea4e01..f407f6895f8a 100644 > --- a/sound/core/pcm_lib.c > +++ b/sound/core/pcm_lib.c > @@ -341,7 +341,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, > * the elapsed time to detect xruns. > */ > jdelta = curr_jiffies - runtime->hw_ptr_jiffies; > - if (jdelta < runtime->hw_ptr_buffer_jiffies / 2) > + if ((jdelta < runtime->hw_ptr_buffer_jiffies / 2) || > + !runtime->hw_ptr_buffer_jiffies) > goto no_delta_check; > hdelta = jdelta - delta * HZ / runtime->rate; > xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1; > -- > 2.21.0 >
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index d80041ea4e01..f407f6895f8a 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -341,7 +341,8 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream, * the elapsed time to detect xruns. */ jdelta = curr_jiffies - runtime->hw_ptr_jiffies; - if (jdelta < runtime->hw_ptr_buffer_jiffies / 2) + if ((jdelta < runtime->hw_ptr_buffer_jiffies / 2) || + !runtime->hw_ptr_buffer_jiffies) goto no_delta_check; hdelta = jdelta - delta * HZ / runtime->rate; xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1;