X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=786a80d6b16b1936dc62b71b43db18850854dd41;hp=5b341b5cfd6d97034b08ca5ea6df913a0c8a7736;hb=882f335739b978d1c55be2faeed077f315afe5d7;hpb=708d89f0b396d20522fe87cc80d91072bb9fcb02

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 5b341b5..786a80d 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -43,6 +43,7 @@
 #include "urcu/tls-compat.h"
 
 #include "urcu-die.h"
+#include "urcu-wait.h"
 
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #undef _LGPL_SOURCE
@@ -78,6 +79,12 @@ DEFINE_URCU_TLS(unsigned int, rcu_rand_yield);
 
 static CDS_LIST_HEAD(registry);
 
+/*
+ * Queue keeping threads awaiting to wait for a grace period. Contains
+ * struct gp_waiters_thread objects.
+ */
+static DEFINE_URCU_WAIT_QUEUE(gp_waiters);
+
 static void mutex_lock(pthread_mutex_t *mutex)
 {
 	int ret;
@@ -198,8 +205,10 @@ void synchronize_rcu(void)
 	CDS_LIST_HEAD(cur_snap_readers);
 	CDS_LIST_HEAD(qsreaders);
 	unsigned long was_online;
+	DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
+	struct urcu_waiters waiters;
 
-	was_online = URCU_TLS(rcu_reader).ctr;
+	was_online = rcu_read_ongoing();
 
 	/* All threads should read qparity before accessing data structure
 	 * where new ptr points to.  In the "then" case, rcu_thread_offline
@@ -214,8 +223,26 @@ void synchronize_rcu(void)
 	else
 		cmm_smp_mb();
 
+	/*
+	 * Add ourself to gp_waiters queue of threads awaiting to wait
+	 * for a grace period. Proceed to perform the grace period only
+	 * if we are the first thread added into the queue.
+	 */
+	if (urcu_wait_add(&gp_waiters, &wait) != 0) {
+		/* Not first in queue: will be awakened by another thread. */
+		urcu_adaptative_busy_wait(&wait);
+		goto gp_end;
+	}
+	/* We won't need to wake ourself up */
+	urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
+
 	mutex_lock(&rcu_gp_lock);
 
+	/*
+	 * Move all waiters into our local queue.
+	 */
+	urcu_move_waiters(&waiters, &gp_waiters);
+
 	if (cds_list_empty(&registry))
 		goto out;
 
@@ -271,7 +298,8 @@ void synchronize_rcu(void)
 	cds_list_splice(&qsreaders, &registry);
 out:
 	mutex_unlock(&rcu_gp_lock);
-
+	urcu_wake_all_waiters(&waiters);
+gp_end:
 	/*
 	 * Finish waiting for reader threads before letting the old ptr being
 	 * freed.
@@ -286,8 +314,10 @@ void synchronize_rcu(void)
 {
 	CDS_LIST_HEAD(qsreaders);
 	unsigned long was_online;
+	DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
+	struct urcu_waiters waiters;
 
-	was_online = URCU_TLS(rcu_reader).ctr;
+	was_online = rcu_read_ongoing();
 
 	/*
 	 * Mark the writer thread offline to make sure we don't wait for
@@ -299,7 +329,26 @@ void synchronize_rcu(void)
 	else
 		cmm_smp_mb();
 
+	/*
+	 * Add ourself to gp_waiters queue of threads awaiting to wait
+	 * for a grace period. Proceed to perform the grace period only
+	 * if we are the first thread added into the queue.
+	 */
+	if (urcu_wait_add(&gp_waiters, &wait) != 0) {
+		/* Not first in queue: will be awakened by another thread. */
+		urcu_adaptative_busy_wait(&wait);
+		goto gp_end;
+	}
+	/* We won't need to wake ourself up */
+	urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
+
 	mutex_lock(&rcu_gp_lock);
+
+	/*
+	 * Move all waiters into our local queue.
+	 */
+	urcu_move_waiters(&waiters, &gp_waiters);
+
 	if (cds_list_empty(&registry))
 		goto out;
 
@@ -333,7 +382,8 @@ void synchronize_rcu(void)
 	cds_list_splice(&qsreaders, &registry);
 out:
 	mutex_unlock(&rcu_gp_lock);
-
+	urcu_wake_all_waiters(&waiters);
+gp_end:
 	if (was_online)
 		rcu_thread_online();
 	else
@@ -355,6 +405,11 @@ void rcu_read_unlock(void)
 	_rcu_read_unlock();
 }
 
+int rcu_read_ongoing(void)
+{
+	return _rcu_read_ongoing();
+}
+
 void rcu_quiescent_state(void)
 {
 	_rcu_quiescent_state();