/*
* Unlock write lock
* Start any waiting writers in preference to waiting readers
*/
int devlock::writeunlock()
{
devlock *rwl = this;
int status, status2;
if (rwl->valid != DEVLOCK_VALID) {
return EINVAL;
}
if ((status = pthread_mutex_lock(&rwl->mutex)) != 0) {
return status;
}
if (rwl->w_active <= 0) {
pthread_mutex_unlock(&rwl->mutex);
Jmsg0(NULL, M_ABORT, 0, _("writeunlock called too many times.\n"));
}
rwl->w_active--;
if (!pthread_equal(pthread_self(), rwl->writer_id)) {
pthread_mutex_unlock(&rwl->mutex);
Jmsg0(NULL, M_ABORT, 0, _("writeunlock by non-owner.\n"));
}
if (rwl->w_active > 0) {
status = 0; /* writers still active */
} else {
lmgr_do_unlock(rwl);
/* No more writers, awaken someone */
if (rwl->r_wait > 0) { /* if readers waiting */
status = pthread_cond_broadcast(&rwl->read);
} else if (rwl->w_wait > 0) {
status = pthread_cond_broadcast(&rwl->write);
}
}
status2 = pthread_mutex_unlock(&rwl->mutex);
return (status == 0 ? status2 : status);
}
/*
* Lock for write access, wait until locked (or error).
* Multiple nested write locking is permitted.
*/
int devlock::writelock(int areason, bool acan_take)
{
devlock *rwl = this;
int status;
if (rwl->valid != DEVLOCK_VALID) {
return EINVAL;
}
if ((status = pthread_mutex_lock(&rwl->mutex)) != 0) {
return status;
}
if (rwl->w_active && pthread_equal(rwl->writer_id, pthread_self())) {
rwl->w_active++;
pthread_mutex_unlock(&rwl->mutex);
return 0;
}
lmgr_pre_lock(rwl, rwl->priority, __FILE__, __LINE__);
if (rwl->w_active || rwl->r_active > 0) {
rwl->w_wait++; /* indicate that we are waiting */
pthread_cleanup_push(devlock_write_release, (void *)rwl);
while (rwl->w_active || rwl->r_active > 0) {
if ((status = pthread_cond_wait(&rwl->write, &rwl->mutex)) != 0) {
lmgr_do_unlock(rwl);
break; /* error, bail out */
}
}
pthread_cleanup_pop(0);
rwl->w_wait--; /* we are no longer waiting */
}
if (status == 0) {
rwl->w_active++; /* we are running */
rwl->writer_id = pthread_self(); /* save writer thread's id */
lmgr_post_lock();
}
rwl->reason = areason;
rwl->can_take = acan_take;
pthread_mutex_unlock(&rwl->mutex);
return status;
}
/*
* Lock for write access, wait until locked (or error).
* Multiple nested write locking is permitted.
*/
int rwl_writelock_p(brwlock_t *rwl, const char *file, int line)
{
int stat;
if (rwl->valid != RWLOCK_VALID) {
return EINVAL;
}
if ((stat = pthread_mutex_lock(&rwl->mutex)) != 0) {
return stat;
}
if (rwl->w_active && pthread_equal(rwl->writer_id, pthread_self())) {
rwl->w_active++;
pthread_mutex_unlock(&rwl->mutex);
return 0;
}
lmgr_pre_lock(rwl, rwl->priority, file, line);
if (rwl->w_active || rwl->r_active > 0) {
rwl->w_wait++; /* indicate that we are waiting */
pthread_cleanup_push(rwl_write_release, (void *)rwl);
while (rwl->w_active || rwl->r_active > 0) {
if ((stat = pthread_cond_wait(&rwl->write, &rwl->mutex)) != 0) {
lmgr_do_unlock(rwl);
break; /* error, bail out */
}
}
pthread_cleanup_pop(0);
rwl->w_wait--; /* we are no longer waiting */
}
if (stat == 0) {
rwl->w_active++; /* we are running */
rwl->writer_id = pthread_self(); /* save writer thread's id */
lmgr_post_lock();
}
pthread_mutex_unlock(&rwl->mutex);
return stat;
}