Tom 7593418b77 Kernel: Fix futex race that could lead to thread waiting forever ...

There is a race condition where we would remove a FutexQueue from
our futex map and in the meanwhile another thread started to queue
itself into that very same futex, leading to that thread to wait
forever as no other wake operation could discover that removed
FutexQueue.

This fixes the problem by:
* Tracking imminent waits, which prevents a new FutexQueue from being
  deleted that a thread will wait on momentarily
* Atomically marking a FutexQueue as removed, which prevents a thread
  from waiting on it before it is actually removed from the futex map.

2021-07-07 10:05:55 +02:00

5.9 KiB

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