fix(alsa): hanging double-opens with BufferSize::Fixed om some drivers#1214
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roderickvd wants to merge 2 commits into
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fix(alsa): hanging double-opens with BufferSize::Fixed om some drivers#1214roderickvd wants to merge 2 commits into
roderickvd wants to merge 2 commits into
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Pull request overview
This PR updates the ALSA backend to avoid an extra open/close cycle when validating BufferSize::Fixed (which can leave some drivers in a bad state), and adds a defensive PCM-state check when poll() times out to prevent hangs when error events aren’t delivered.
Changes:
- Move
BufferSize::Fixedrange validation toset_hw_params_from_format()so it uses the same PCM handle as the streaming open (avoids a second open/close). - On
poll()timeout, query PCM state and surfaceDisconnected/XRun/Suspendedconditions even ifPOLLERR/POLLHUPwasn’t delivered.
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| // Validate the requested size against the device's supported range using the same PCM | ||
| // handle we'll use for streaming. This avoids a second PCM open (which can disturb | ||
| // hardware clock state on some drivers) while still catching wildly out-of-range | ||
| // requests before set_period_size_near silently rounds them. | ||
| let (min_buffer, max_buffer) = hw_params_buffer_size_min_max(&hw_params); | ||
| if !(min_buffer..=max_buffer).contains(&buffer_frames) { | ||
| return Err(Error::with_message( | ||
| ErrorKind::UnsupportedConfig, | ||
| format!("Buffer size {buffer_frames} is not in the supported range {min_buffer}..={max_buffer}"), | ||
| )); | ||
| } | ||
| hw_params.set_buffer_size_near(DEFAULT_PERIODS * buffer_frames as alsa::pcm::Frames)?; |
roderickvd
changed the title
|
As I wrote in the issue there are no apparent changes for me, but it also does not negatively effect the current behavior on the rasperry pi zero w, so I would say its better than before. |
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The range validation for
BufferSize::Fixedwas callingdefault_output_config()before opening the stream, which opened and closed the PCM device once just to get the buffer size range. This may leave the driver in a bad state for the subsequent streaming open.Second, to defend against hanging processes in such an event, the worker now checks PCM state when
poll()times out.Fixes #1157