void __attribute__((constructor)) rcu_init(void);
void __attribute__((destructor)) rcu_exit(void);
+
+static DEFINE_URCU_TLS(int, rcu_signal_was_blocked);
#endif
/*
smp_mb_master();
/* Temporarily unlock the registry lock. */
mutex_unlock(&rcu_registry_lock);
- if (uatomic_read(&rcu_gp.futex) != -1)
- goto end;
- while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
- NULL, NULL, 0)) {
+ while (uatomic_read(&rcu_gp.futex) == -1) {
+ if (!futex_async(&rcu_gp.futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+ /*
+ * Prior queued wakeups queued by unrelated code
+ * using the same address can cause futex wait to
+ * return 0 even through the futex value is still
+ * -1 (spurious wakeups). Check the value again
+ * in user-space to validate whether it really
+ * differs from -1.
+ */
+ continue;
+ }
switch (errno) {
- case EWOULDBLOCK:
+ case EAGAIN:
/* Value already changed. */
goto end;
case EINTR:
/* Retry if interrupted by signal. */
- break; /* Get out of switch. */
+ break; /* Get out of switch. Check again. */
default:
/* Unexpected error. */
urcu_die(errno);
return _rcu_read_ongoing();
}
+#ifdef RCU_SIGNAL
+/*
+ * Make sure the signal used by the urcu-signal flavor is unblocked
+ * while the thread is registered.
+ */
+static
+void urcu_signal_unblock(void)
+{
+ sigset_t mask, oldmask;
+ int ret;
+
+ ret = sigemptyset(&mask);
+ urcu_posix_assert(!ret);
+ ret = sigaddset(&mask, SIGRCU);
+ urcu_posix_assert(!ret);
+ ret = pthread_sigmask(SIG_UNBLOCK, &mask, &oldmask);
+ urcu_posix_assert(!ret);
+ URCU_TLS(rcu_signal_was_blocked) = sigismember(&oldmask, SIGRCU);
+}
+
+static
+void urcu_signal_restore(void)
+{
+ sigset_t mask;
+ int ret;
+
+ if (!URCU_TLS(rcu_signal_was_blocked))
+ return;
+ ret = sigemptyset(&mask);
+ urcu_posix_assert(!ret);
+ ret = sigaddset(&mask, SIGRCU);
+ urcu_posix_assert(!ret);
+ ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
+ urcu_posix_assert(!ret);
+}
+#else
+static
+void urcu_signal_unblock(void) { }
+static
+void urcu_signal_restore(void) { }
+#endif
+
void rcu_register_thread(void)
{
+ urcu_signal_unblock();
+
URCU_TLS(rcu_reader).tid = pthread_self();
urcu_posix_assert(URCU_TLS(rcu_reader).need_mb == 0);
urcu_posix_assert(!(URCU_TLS(rcu_reader).ctr & URCU_GP_CTR_NEST_MASK));
URCU_TLS(rcu_reader).registered = 0;
cds_list_del(&URCU_TLS(rcu_reader).node);
mutex_unlock(&rcu_registry_lock);
+
+ urcu_signal_restore();
}
#ifdef RCU_MEMBARRIER
#include "urcu-call-rcu-impl.h"
#include "urcu-defer-impl.h"
+#include "urcu-poll-impl.h"