async_context_threadsafe_background: fix incorrect mutex assertion in cross-core execute_sync() #2528
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… cross-core execute_sync() In multicore configurations, `async_context_threadsafe_background_execute_sync()` contained an overly strict assertion used during cross-core calls: ```c hard_assert(!recursive_mutex_enter_count(&self->lock_mutex)); ``` This check fails whenever the `lock_mutex` is held — regardless of *who* owns it — even in valid situations where the async core is processing background work. The assertion does **not check ownership**, only that the `enter_count` is zero, which leads to false-positive failures on valid cross-core calls. This patch replaces the enter-count check with a core-aware assertion: ```c hard_assert(self->lock_mutex.owner != calling_core); ``` This ensures the current core does not recursively hold the mutex, preventing deadlocks while allowing valid usage where the *other* core owns the lock. The patch ensures that both `get_core_num()` and `hard_assert()` remain inlined as in the original implementation, preserving the performance characteristics under `-Os` and `RelWithDebInfo` builds. Fixes raspberrypi#2527 Signed-off-by: Goran Mišković <[email protected]>
Use pre-existing mutex owner method; add a comment
lurch
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Jun 17, 2025
src/rp2_common/pico_async_context/async_context_threadsafe_background.c
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schkovich
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Jun 17, 2025
src/rp2_common/pico_async_context/async_context_threadsafe_background.c
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kilograham
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Jun 18, 2025
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In multicore configurations,
async_context_threadsafe_background_execute_sync()contained an overly strict assertion used during cross-core calls:This check fails whenever the
lock_mutexis held — regardless of who owns it — even in valid situations where the async core is processing background work.The assertion does not check ownership, only that the
enter_countis zero, which leads to false-positive failures on valid cross-core calls.This patch replaces the enter-count check with a core-aware assertion:
This ensures the current core does not recursively hold the mutex, preventing deadlocks while allowing valid usage where the other core owns the lock.
The patch ensures that both
get_core_num()andhard_assert()remain inlined as in the original implementation, preserving the performance characteristics under-OsandRelWithDebInfobuilds.Fixes #2527