X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-qsbr.c;h=d69138974722d881d9345a105f48a6c4870d8f45;hp=5b341b5cfd6d97034b08ca5ea6df913a0c8a7736;hb=cba82d7bd73c2d3d9772190d51314c59bd2ef309;hpb=708d89f0b396d20522fe87cc80d91072bb9fcb02

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 5b341b5..d691389 100644
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -36,6 +36,7 @@
 #include <poll.h>
 
 #include "urcu/wfcqueue.h"
+#include "urcu/wfstack.h"
 #include "urcu/map/urcu-qsbr.h"
 #define BUILD_QSBR_LIB
 #include "urcu/static/urcu-qsbr.h"
@@ -43,6 +44,7 @@
 #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 +80,20 @@ DEFINE_URCU_TLS(unsigned int, rcu_rand_yield);
 
 static CDS_LIST_HEAD(registry);
 
+struct gp_waiters_thread {
+	struct cds_wfs_node node;
+	struct urcu_wait wait;
+};
+
+/*
+ * Stack keeping threads awaiting to wait for a grace period. Contains
+ * struct gp_waiters_thread objects.
+ */
+static struct cds_wfs_stack gp_waiters = {
+	.head = CDS_WFS_END,
+	.lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
 static void mutex_lock(pthread_mutex_t *mutex)
 {
 	int ret;
@@ -198,6 +214,9 @@ void synchronize_rcu(void)
 	CDS_LIST_HEAD(cur_snap_readers);
 	CDS_LIST_HEAD(qsreaders);
 	unsigned long was_online;
+	struct gp_waiters_thread gp_waiters_thread;
+	struct cds_wfs_head *gp_waiters_head;
+	struct cds_wfs_node *waiters_iter, *waiters_iter_n;
 
 	was_online = URCU_TLS(rcu_reader).ctr;
 
@@ -214,8 +233,26 @@ void synchronize_rcu(void)
 	else
 		cmm_smp_mb();
 
+	/*
+	 * Add ourself to gp_waiters stack 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 stack.
+	 */
+	cds_wfs_node_init(&gp_waiters_thread.node);
+	urcu_wait_init(&gp_waiters_thread.wait);
+	if (cds_wfs_push(&gp_waiters, &gp_waiters_node) != 0) {
+		/* Not first in stack: will be awakened by another thread. */
+		urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
+		goto gp_end;
+	}
+
 	mutex_lock(&rcu_gp_lock);
 
+	/*
+	 * Pop all waiters into our local stack head.
+	 */
+	gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+
 	if (cds_list_empty(&registry))
 		goto out;
 
@@ -272,6 +309,19 @@ void synchronize_rcu(void)
 out:
 	mutex_unlock(&rcu_gp_lock);
 
+	/* Wake all waiters in our stack head, excluding ourself. */
+	cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter,
+				waiters_iter_n) {
+		struct gp_waiters_thread *wt;
+
+		wt = caa_container_of(waiters_iter,
+				struct gp_waiters_thread, node);
+		if (wt == &gp_waiters_thread)
+			continue;
+		urcu_adaptative_wake_up(&wt->wait);
+	}
+
+gp_end:
 	/*
 	 * Finish waiting for reader threads before letting the old ptr being
 	 * freed.
@@ -286,6 +336,9 @@ void synchronize_rcu(void)
 {
 	CDS_LIST_HEAD(qsreaders);
 	unsigned long was_online;
+	struct gp_waiters_thread gp_waiters_thread;
+	struct cds_wfs_head *gp_waiters_head;
+	struct cds_wfs_node *waiters_iter, *waiters_iter_n;
 
 	was_online = URCU_TLS(rcu_reader).ctr;
 
@@ -299,7 +352,26 @@ void synchronize_rcu(void)
 	else
 		cmm_smp_mb();
 
+	/*
+	 * Add ourself to gp_waiters stack 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 stack.
+	 */
+	cds_wfs_node_init(&gp_waiters_thread.node);
+	urcu_wait_init(&gp_waiters_thread.wait);
+	if (cds_wfs_push(&gp_waiters, &gp_waiters_thread.node) != 0) {
+		/* Not first in stack: will be awakened by another thread. */
+		urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
+		goto gp_end;
+	}
+
 	mutex_lock(&rcu_gp_lock);
+
+	/*
+	 * Pop all waiters into our local stack head.
+	 */
+	gp_waiters_head = __cds_wfs_pop_all(&gp_waiters);
+
 	if (cds_list_empty(&registry))
 		goto out;
 
@@ -334,6 +406,19 @@ void synchronize_rcu(void)
 out:
 	mutex_unlock(&rcu_gp_lock);
 
+	/* Wake all waiters in our stack head, excluding ourself. */
+	cds_wfs_for_each_blocking_safe(gp_waiters_head, waiters_iter,
+				waiters_iter_n) {
+		struct gp_waiters_thread *wt;
+
+		wt = caa_container_of(waiters_iter,
+				struct gp_waiters_thread, node);
+		if (wt == &gp_waiters_thread)
+			continue;
+		urcu_adaptative_wake_up(&wt->wait);
+	}
+
+gp_end:
 	if (was_online)
 		rcu_thread_online();
 	else