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-rw-r--r--src/internal/pthread_impl.h2
-rw-r--r--src/thread/pthread_barrier_wait.c24
2 files changed, 14 insertions, 12 deletions
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 82d62426..dd3863fc 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -77,7 +77,7 @@ struct __timer {
#define _b_waiters __u.__i[1]
#define _b_limit __u.__i[2]
#define _b_count __u.__i[3]
-#define _b_seq __u.__i[4]
+#define _b_waiters2 __u.__i[4]
#define _b_inst __u.__p[4]
#include "pthread_arch.h"
diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c
index 9b1edbf9..71f7b5fe 100644
--- a/src/thread/pthread_barrier_wait.c
+++ b/src/thread/pthread_barrier_wait.c
@@ -21,7 +21,6 @@ void __vm_unlock(void)
static int pshared_barrier_wait(pthread_barrier_t *b)
{
int limit = (b->_b_limit & INT_MAX) + 1;
- int seq;
int ret = 0;
int v, w;
@@ -30,33 +29,36 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
while ((v=a_cas(&b->_b_lock, 0, limit)))
__wait(&b->_b_lock, &b->_b_waiters, v, 0);
- seq = b->_b_seq;
-
+ /* Wait for <limit> threads to get to the barrier */
if (++b->_b_count == limit) {
+ a_store(&b->_b_count, 0);
ret = PTHREAD_BARRIER_SERIAL_THREAD;
- b->_b_seq++;
- __wake(&b->_b_seq, -1, 0);
+ 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);
- __wait(&b->_b_seq, 0, seq, 0);
+ while ((v=b->_b_count)>0)
+ __wait(&b->_b_count, &b->_b_waiters2, v, 0);
}
__vm_lock(+1);
- if (a_fetch_add(&b->_b_count, -1)==1) {
- b->_b_seq++;
- __wake(&b->_b_seq, -1, 0);
+ /* 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 {
- __wait(&b->_b_seq, 0, seq+1, 0);
+ 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-1 & INT_MAX) != v);
+ } 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);