X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fthread%2Fpthread_barrier_wait.c;h=5e6033804033b85879ba88abdaf1d5d0b4aa14af;hb=52d4444f8eec1a4e7e0861859c705c3a558b4e2a;hp=aed1adc855f77a2da34b0d8c5c0247858380ef35;hpb=9dd6399c95ed3ebc62492f6dedc569b5f0d8bb8e;p=musl diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c index aed1adc8..5e603380 100644 --- a/src/thread/pthread_barrier_wait.c +++ b/src/thread/pthread_barrier_wait.c @@ -1,5 +1,57 @@ #include "pthread_impl.h" +void __vm_lock_impl(int); +void __vm_unlock_impl(void); + +static int pshared_barrier_wait(pthread_barrier_t *b) +{ + int limit = (b->_b_limit & INT_MAX) + 1; + int ret = 0; + int v, w; + + if (limit==1) return PTHREAD_BARRIER_SERIAL_THREAD; + + while ((v=a_cas(&b->_b_lock, 0, limit))) + __wait(&b->_b_lock, &b->_b_waiters, v, 0); + + /* Wait for threads to get to the barrier */ + if (++b->_b_count == limit) { + a_store(&b->_b_count, 0); + ret = PTHREAD_BARRIER_SERIAL_THREAD; + if (b->_b_waiters2) __wake(&b->_b_count, -1, 0); + } else { + a_store(&b->_b_lock, 0); + if (b->_b_waiters) __wake(&b->_b_lock, 1, 0); + while ((v=b->_b_count)>0) + __wait(&b->_b_count, &b->_b_waiters2, v, 0); + } + + __vm_lock_impl(+1); + + /* Ensure all threads have a vm lock before proceeding */ + if (a_fetch_add(&b->_b_count, -1)==1-limit) { + a_store(&b->_b_count, 0); + if (b->_b_waiters2) __wake(&b->_b_count, -1, 0); + } else { + while ((v=b->_b_count)) + __wait(&b->_b_count, &b->_b_waiters2, v, 0); + } + + /* Perform a recursive unlock suitable for self-sync'd destruction */ + do { + v = b->_b_lock; + w = b->_b_waiters; + } while (a_cas(&b->_b_lock, v, v==INT_MIN+1 ? 0 : v-1) != v); + + /* Wake a thread waiting to reuse or destroy the barrier */ + if (v==INT_MIN+1 || (v==1 && w)) + __wake(&b->_b_lock, 1, 0); + + __vm_unlock_impl(); + + return ret; +} + struct instance { int count; @@ -16,9 +68,12 @@ int pthread_barrier_wait(pthread_barrier_t *b) /* Trivial case: count was set at 1 */ if (!limit) return PTHREAD_BARRIER_SERIAL_THREAD; + /* Process-shared barriers require a separate, inefficient wait */ + if (limit < 0) return pshared_barrier_wait(b); + /* Otherwise we need a lock on the barrier object */ while (a_swap(&b->_b_lock, 1)) - __wait(&b->_b_lock, &b->_b_waiters, 1, 0); + __wait(&b->_b_lock, &b->_b_waiters, 1, 1); inst = b->_b_inst; /* First thread to enter the barrier becomes the "instance owner" */ @@ -27,7 +82,7 @@ int pthread_barrier_wait(pthread_barrier_t *b) int spins = 10000; b->_b_inst = inst = &new_inst; a_store(&b->_b_lock, 0); - if (b->_b_waiters) __wake(&b->_b_lock, 1, 0); + if (b->_b_waiters) __wake(&b->_b_lock, 1, 1); while (spins-- && !inst->finished) a_spin(); a_inc(&inst->finished); @@ -40,19 +95,19 @@ int pthread_barrier_wait(pthread_barrier_t *b) if (++inst->count == limit) { b->_b_inst = 0; a_store(&b->_b_lock, 0); - if (b->_b_waiters) __wake(&b->_b_lock, 1, 0); + if (b->_b_waiters) __wake(&b->_b_lock, 1, 1); a_store(&inst->last, 1); if (inst->waiters) - __wake(&inst->last, -1, 0); + __wake(&inst->last, -1, 1); } else { a_store(&b->_b_lock, 0); - if (b->_b_waiters) __wake(&b->_b_lock, 1, 0); - __wait(&inst->last, &inst->waiters, 0, 0); + if (b->_b_waiters) __wake(&b->_b_lock, 1, 1); + __wait(&inst->last, &inst->waiters, 0, 1); } /* Last thread to exit the barrier wakes the instance owner */ if (a_fetch_add(&inst->count,-1)==1 && a_fetch_add(&inst->finished,1)) - __wake(&inst->finished, 1, 0); + __wake(&inst->finished, 1, 1); return 0; }