pthread_rwlock_unlock(3)pthread_rwlock_unlock(3)NAMEpthread_rwlock_unlock - Unlock a read-write lock
SYNOPSIS
#include <pthread.h>
int pthread_rwlock_unlock(
pthread_rwlock_t *rwlock );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
PARAMETERS
Address of the read-write lock to be unlocked.
DESCRIPTION
This routine releases a lock acquisition held on the read-write lock
object referenced by rwlock. Results are undefined if rwlock is not
held by the calling thread.
If this routine is called to release a lock for read access on rwlock
and the calling thread also currently holds other locks for read access
on rwlock, the read-write lock object remains in the read locked state.
If this routine releases the calling thread's last lock for read access
on rwlock, the calling thread is not longer one of the owners of the
lock object.
If this routine is called to release a lock for write access on rwlock,
the lock object is put in the unlocked state with no owners.
If a call to this routine results in the read-write lock object becom‐
ing unlocked and there are multiple thread waiting to acquire that lock
for write access, DECthreads uses the scheduling policy of those wait‐
ing threads to determine which thread next acquires the lock object for
write access. If there are multiple thread waiting to acquire the read-
write lock object for read access, DECthreads uses the scheduling pol‐
icy of those waiting threads to determine the order in which those
threads acquire the lock for read access. If there are multiple
threads waiting to acquire the read-write lock object for both read and
write access, it is unspecified whether a thread waiting for read
access or for write access next acquires the lock object.
If the read-write lock object referenced by rwlock is not initialized,
the results of calling this routine are undefined.
RETURN VALUES
If an error condition occurs, this routine returns an integer value
indicating the type of error. Possible return values are as follows:
Successful completion. The values specified by rwlock does not refer
to an initialized read-write lock object. The current thread does not
hold the read-write lock object.
ERRORS
None
SEE ALSO
Functions: pthread_rwlock_init(3), pthread_rwlock_rdlock(3),
pthread_rwlock_wrlock(3), pthread_rwlockattr_init(3)
Manuals: Guide to DECthreads and Programmer's Guide
pthread_rwlock_unlock(3)
