Disable signals in URCU background threads

[userspace-rcu.git] / src / urcu.c

diff --git a/src/urcu.c b/src/urcu.c
index 59f2e8f18fdddc5a781e25d2478ca86e18a9fee5..cf4d6d03f711750c05e91991f2a64687640b4438 100644 (file)
--- a/src/urcu.c
+++ b/src/urcu.c
@@ -110,6 +110,8 @@ static int init_done;
 
 void __attribute__((constructor)) rcu_init(void);
 void __attribute__((destructor)) rcu_exit(void);
+
+static DEFINE_URCU_TLS(int, rcu_signal_was_blocked);
 #endif
 
 /*
@@ -537,8 +539,52 @@ int rcu_read_ongoing(void)
        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));
@@ -558,6 +604,8 @@ void rcu_unregister_thread(void)
        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