Fix: handle sys_futex() FUTEX_WAIT interrupted by signal

[userspace-rcu.git] / urcu / static / urcu-qsbr.h

diff --git a/urcu/static/urcu-qsbr.h b/urcu/static/urcu-qsbr.h
index 22908a45f95c6a6c77988ab73acd8baaa97e7f15..bf97a40c1a9b5345d7110f60b958b63dd0af61f0 100644 (file)
--- a/urcu/static/urcu-qsbr.h
+++ b/urcu/static/urcu-qsbr.h
@@ -6,8 +6,8 @@
  *
  * Userspace RCU QSBR header.
  *
- * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-qsbr.h for linking
- * dynamically with the userspace rcu QSBR library.
+ * TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU
+ * RELEASE. See urcu.h for linking dynamically with the userspace rcu library.
  *
  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
@@ -93,7 +93,7 @@ static inline void debug_yield_write(void)
 
 static inline void debug_yield_init(void)
 {
-       URCU_TLS(rand_yield) = time(NULL) ^ pthread_self();
+       URCU_TLS(rand_yield) = time(NULL) ^ (unsigned long) pthread_self();
 }
 #else
 static inline void debug_yield_read(void)
@@ -144,8 +144,13 @@ static inline void wake_up_gp(void)
                if (uatomic_read(&gp_futex) != -1)
                        return;
                uatomic_set(&gp_futex, 0);
-               futex_noasync(&gp_futex, FUTEX_WAKE, 1,
-                     NULL, NULL, 0);
+               /*
+                * Ignoring return value until we can make this function
+                * return something (because urcu_die() is not publicly
+                * exposed).
+                */
+               (void) futex_noasync(&gp_futex, FUTEX_WAKE, 1,
+                               NULL, NULL, 0);
        }
 }
 
@@ -157,15 +162,36 @@ static inline int rcu_gp_ongoing(unsigned long *ctr)
        return v && (v != rcu_gp_ctr);
 }
 
+/*
+ * Enter an RCU read-side critical section.
+ *
+ * This function is less than 10 lines long.  The intent is that this
+ * function meets the 10-line criterion for LGPL, allowing this function
+ * to be invoked directly from non-LGPL code.
+ */
 static inline void _rcu_read_lock(void)
 {
        rcu_assert(URCU_TLS(rcu_reader).ctr);
 }
 
+/*
+ * Exit an RCU read-side critical section.
+ *
+ * This function is less than 10 lines long.  The intent is that this
+ * function meets the 10-line criterion for LGPL, allowing this function
+ * to be invoked directly from non-LGPL code.
+ */
 static inline void _rcu_read_unlock(void)
 {
 }
 
+/*
+ * Inform RCU of a quiescent state.
+ *
+ * This function is less than 10 lines long.  The intent is that this
+ * function meets the 10-line criterion for LGPL, allowing this function
+ * to be invoked directly from non-LGPL code.
+ */
 static inline void _rcu_quiescent_state(void)
 {
        cmm_smp_mb();
@@ -175,6 +201,14 @@ static inline void _rcu_quiescent_state(void)
        cmm_smp_mb();
 }
 
+/*
+ * Take a thread offline, prohibiting it from entering further RCU
+ * read-side critical sections.
+ *
+ * This function is less than 10 lines long.  The intent is that this
+ * function meets the 10-line criterion for LGPL, allowing this function
+ * to be invoked directly from non-LGPL code.
+ */
 static inline void _rcu_thread_offline(void)
 {
        cmm_smp_mb();
@@ -184,6 +218,14 @@ static inline void _rcu_thread_offline(void)
        cmm_barrier();  /* Ensure the compiler does not reorder us with mutex */
 }
 
+/*
+ * Bring a thread online, allowing it to once again enter RCU
+ * read-side critical sections.
+ *
+ * This function is less than 10 lines long.  The intent is that this
+ * function meets the 10-line criterion for LGPL, allowing this function
+ * to be invoked directly from non-LGPL code.
+ */
 static inline void _rcu_thread_online(void)
 {
        cmm_barrier();  /* Ensure the compiler does not reorder us with mutex */