[v0.19] Fix Buffer Mapping Deadlock #5517
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Wumpf
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Apr 14, 2024
Wumpf
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Apr 17, 2024
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changelog got promised to be done upon the release processing :) |
REASY
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Apr 20, 2024
| // This _cannot_ be inlined into the match. If it is, the lock will be held | ||
| // open through the whole match, resulting in a deadlock when we try to re-lock | ||
| // the buffer back to active. | ||
| let mapping = std::mem::replace( | ||
| &mut *buffer.map_state.lock(), |
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Should ReentrantMutex used to prevent double locking causing deadlock?
A mutex which can be recursively locked by a single thread.
This type is identical to Mutex except for the following points:
- Locking multiple times from the same thread will work correctly instead of deadlocking.
- ReentrantMutexGuard does not give mutable references to the locked data. Use a RefCell if you need this.
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No - there is a cost to reentrant mutexes and none of our mutexes require reentrency.
We have a PR open which adds a debug check to make sure we don't lock locks in a way that could cause a deadlock.
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Found this while using wgpu-profiler.
Subtle temporary extension caused a deadlock in buffer mapping code.