Fix: compat futex duplicated lock and completion

[urcu.git] / compat_futex.c

diff --git a/compat_futex.c b/compat_futex.c
index bb928e61d6849fc90f63ab5b07fcf82718f28990..e7342fe38ccda2330b45e157cd0c1d7cb02cd3ef 100644 (file)
--- a/compat_futex.c
+++ b/compat_futex.c
@@ -31,8 +31,18 @@
 #include <urcu/arch.h>
 #include <urcu/futex.h>
 
-static pthread_mutex_t compat_futex_lock = PTHREAD_MUTEX_INITIALIZER;
-static pthread_cond_t compat_futex_cond = PTHREAD_COND_INITIALIZER;
+/*
+ * Using attribute "weak" for __urcu_compat_futex_lock and
+ * __urcu_compat_futex_cond. Those are globally visible by the entire
+ * program, even though many shared objects may have their own version.
+ * The first version that gets loaded will be used by the entire program
+ * (executable and all shared objects).
+ */
+
+__attribute__((weak))
+pthread_mutex_t __urcu_compat_futex_lock = PTHREAD_MUTEX_INITIALIZER;
+__attribute__((weak))
+pthread_cond_t __urcu_compat_futex_cond = PTHREAD_COND_INITIALIZER;
 
 /*
  * _NOT SIGNAL-SAFE_. pthread_cond is not signal-safe anyway. Though.
@@ -58,22 +68,22 @@ int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
         */
        cmm_smp_mb();
 
-       ret = pthread_mutex_lock(&compat_futex_lock);
+       ret = pthread_mutex_lock(&__urcu_compat_futex_lock);
        assert(!ret);
        switch (op) {
        case FUTEX_WAIT:
                if (*uaddr != val)
                        goto end;
-               pthread_cond_wait(&compat_futex_cond, &compat_futex_lock);
+               pthread_cond_wait(&__urcu_compat_futex_cond, &__urcu_compat_futex_lock);
                break;
        case FUTEX_WAKE:
-               pthread_cond_broadcast(&compat_futex_cond);
+               pthread_cond_broadcast(&__urcu_compat_futex_cond);
                break;
        default:
                gret = -EINVAL;
        }
 end:
-       ret = pthread_mutex_unlock(&compat_futex_lock);
+       ret = pthread_mutex_unlock(&__urcu_compat_futex_lock);
        assert(!ret);
        return gret;
 }