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authorRich Felker <dalias@aerifal.cx>2011-09-28 18:00:02 -0400
committerRich Felker <dalias@aerifal.cx>2011-09-28 18:00:02 -0400
commit95b147967216a057d51a1b970da777486be716e3 (patch)
tree04d5c77747955dfffea28bb0db6a26759505f8eb /src
parent8f4a115e7d38c31ad8d8c7233eaff2db270aebd8 (diff)
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next step making barrier self-sync'd destruction safe
i think this works, but it can be simplified. (next step)
Diffstat (limited to 'src')
-rw-r--r--src/thread/pthread_barrier_destroy.c8
-rw-r--r--src/thread/pthread_barrier_wait.c16
2 files changed, 18 insertions, 6 deletions
diff --git a/src/thread/pthread_barrier_destroy.c b/src/thread/pthread_barrier_destroy.c
index 3ebc2b39..e0da197a 100644
--- a/src/thread/pthread_barrier_destroy.c
+++ b/src/thread/pthread_barrier_destroy.c
@@ -5,8 +5,12 @@ void __vm_lock(int), __vm_unlock(void);
int pthread_barrier_destroy(pthread_barrier_t *b)
{
if (b->_b_limit < 0) {
- int seq = b->_b_seq;
- if (seq & 1) __wait(&b->_b_seq, 0, seq, 0);
+ if (b->_b_lock) {
+ int v;
+ a_or(&b->_b_lock, INT_MIN);
+ while ((v = b->_b_lock) & INT_MAX)
+ __wait(&b->_b_lock, 0, v, 0);
+ }
__vm_lock(-1);
__vm_unlock();
}
diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c
index a97f6d56..9b1edbf9 100644
--- a/src/thread/pthread_barrier_wait.c
+++ b/src/thread/pthread_barrier_wait.c
@@ -23,11 +23,12 @@ 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;
if (limit==1) return PTHREAD_BARRIER_SERIAL_THREAD;
- while (a_swap(&b->_b_lock, 1))
- __wait(&b->_b_lock, &b->_b_waiters, 1, 0);
+ while ((v=a_cas(&b->_b_lock, 0, limit)))
+ __wait(&b->_b_lock, &b->_b_waiters, v, 0);
seq = b->_b_seq;
@@ -46,12 +47,19 @@ static int pshared_barrier_wait(pthread_barrier_t *b)
if (a_fetch_add(&b->_b_count, -1)==1) {
b->_b_seq++;
__wake(&b->_b_seq, -1, 0);
- a_store(&b->_b_lock, 0);
- if (b->_b_waiters) __wake(&b->_b_lock, 1, 0);
} else {
__wait(&b->_b_seq, 0, seq+1, 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);
+
+ if (v==INT_MIN+1 || (v==1 && w))
+ __wake(&b->_b_lock, 1, 0);
+
__vm_unlock();
return ret;