pthread_cond_wait: Use atomic_t to protect the waiter count #339
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atomic_read is missing from the nuttx headers, it is added later in upstream. !! REMOVE THIS COMMIT WHEN REBASING WITH UPSTREAM !!
Because sem_getvalue modifies errno.
Because sem_getvalue modifies errno.
sem_getvalue returns ERROR and sets errno if it fails, we don't want to return OK in this case, we want to return the non-negated error number.
sem_getvalue returns ERROR and sets errno if it fails, we don't want to return OK in this case, we want to return the non-negated error number.
The load/compare and RMW to wait_count need protection. Using atomic operations should resolve both issues. NOTE: The assumption that the user will call pthread_cond_signal / pthread_cond_broadcast with the mutex given to pthread_cond_wait held is simply not true. It MAY hold it, but it is not forced. Thus, using the user space lock for protecting the wait counter as well is not valid! The pthread_cond_signal() or pthread_cond_broadcast() functions may be called by a thread whether or not it currently owns the mutex that threads calling pthread_cond_wait() or pthread_cond_timedwait() have associated with the condition variable during their waits; however, if predictable scheduling behaviour is required, then that mutex is locked by the thread calling pthread_cond_signal() or pthread_cond_broadcast(). [1] https://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_cond_signal.html
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LGTM; just wondering whether the i2c and fb driver changes are here on purpose (fb we are not even using afaik) ? |
jlaitine
approved these changes
Jan 20, 2025
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They can be dropped / are not tightly related. Just took everything that was changed in the upstream PR. |
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it is ok to keep those! |
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pthread_cond_wait: Use atomic_t to protect the waiter count
From upstream (hopefully)