#11208: POSIX semaphores have incorrect sharing semantics
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Reporter: hamish | Owner: nobody
Type: bug | Status: new
Priority: normal | Milestone: Unscheduled
Component: System/POSIX | Version: R1/Development
Resolution: | Keywords:
Blocked By: | Blocking:
Has a Patch: 1 | Platform: All
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Comment (by hamish):
Attached is a patch which reimplements unnamed POSIX semaphores using the
user_mutex hashtable wait mechanism. Two new system calls are added:
`_user_mutex_sem_acquire` and `_user_mutex_sem_release`.
Unnamed semaphores now consist of an `int32_t` in userspace. Acquires and
releases are done using atomic ops in userspace when the semaphore has no
waiters (when the semaphores value is >= 0). When the semaphore is
contended the value is set to -1 and the system calls are used to acquire
or release.
I've run the POSIX test suite stress tests for semaphores and all seems
well, however I thought I'd post it here for a second opinion first.
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Ticket URL: <https://dev.haiku-os.org/ticket/11208#comment:3>
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