Acquire a Write Lock

rw_wrlock(3THR)

#include <synch.h>  (or #include <thread.h>)

int rw_wrlock(rwlock_t *rwlp);

Use rw_wrlock(3THR) to acquire a write lock on the read-write lock pointed to by rwlp. When the read-write lock is already locked for reading or writing, the calling thread blocks until all the read locks and write locks are released. Only one thread at a time can hold a write lock on a read-write lock. (For POSIX threads, see pthread_rwlock_wrlock(3THR).)

Return Values

rw_wrlock() returns zero after completing successfully. Any other return value indicates that an error occurred. When any of the following conditions occurs, the function fails and returns the corresponding value.

EINVAL

Invalid argument.

EFAULT

rwlp points to an illegal address.