Multithreaded Programming Guide


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

int rw_rdlock(rwlock_t *rwlp);

Use rw_rdlock(3T) to acquire a read lock on the read-write lock pointed to by rwlp. When the read-write lock is already locked for writing, the calling thread blocks until the write lock is released. Otherwise, the read lock is acquired. (For POSIX threads, see "pthread_rwlock_rdlock(3T)".)

Return Values

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


Invalid argument.


rwlp points to an illegal address.