X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-bp.c;h=a823659f78d4ce93d82a23b95dc05216feb9c903;hp=4b3cf01801764c9c132c525876e2cf40ec5895d8;hb=7ff54418ffac313216eac70d7af1474a78c21706;hpb=dd61d0772f8dda35aadf9636ebabfaebf24add6a

diff --git a/urcu-bp.c b/urcu-bp.c
index 4b3cf01..a823659 100644
--- a/urcu-bp.c
+++ b/urcu-bp.c
@@ -109,13 +109,7 @@ unsigned int rcu_yield_active;
 DEFINE_URCU_TLS(unsigned int, rcu_rand_yield);
 #endif
 
-/*
- * Global grace period counter.
- * Contains the current RCU_GP_CTR_PHASE.
- * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path.
- * Written to only by writer with mutex taken. Read by both writer and readers.
- */
-long rcu_gp_ctr = RCU_GP_COUNT;
+struct rcu_gp rcu_gp = { .ctr = RCU_GP_COUNT };
 
 /*
  * Pointer to registry elements. Written to only by each individual reader. Read
@@ -164,25 +158,44 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 		urcu_die(ret);
 }
 
-static void wait_for_readers(void)
+static void wait_for_readers(struct cds_list_head *input_readers,
+			struct cds_list_head *cur_snap_readers,
+			struct cds_list_head *qsreaders)
 {
-	CDS_LIST_HEAD(qsreaders);
 	int wait_loops = 0;
 	struct rcu_reader *index, *tmp;
 
 	/*
 	 * Wait for each thread URCU_TLS(rcu_reader).ctr to either
 	 * indicate quiescence (not nested), or observe the current
-	 * rcu_gp_ctr value.
+	 * rcu_gp.ctr value.
 	 */
 	for (;;) {
 		wait_loops++;
-		cds_list_for_each_entry_safe(index, tmp, &registry, node) {
-			if (!rcu_old_gp_ongoing(&index->ctr))
-				cds_list_move(&index->node, &qsreaders);
+		cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
+			switch (rcu_reader_state(&index->ctr)) {
+			case RCU_READER_ACTIVE_CURRENT:
+				if (cur_snap_readers) {
+					cds_list_move(&index->node,
+						cur_snap_readers);
+					break;
+				}
+				/* Fall-through */
+			case RCU_READER_INACTIVE:
+				cds_list_move(&index->node, qsreaders);
+				break;
+			case RCU_READER_ACTIVE_OLD:
+				/*
+				 * Old snapshot. Leaving node in
+				 * input_readers will make us busy-loop
+				 * until the snapshot becomes current or
+				 * the reader becomes inactive.
+				 */
+				break;
+			}
 		}
 
-		if (cds_list_empty(&registry)) {
+		if (cds_list_empty(input_readers)) {
 			break;
 		} else {
 			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS)
@@ -191,18 +204,18 @@ static void wait_for_readers(void)
 				caa_cpu_relax();
 		}
 	}
-	/* put back the reader list in the registry */
-	cds_list_splice(&qsreaders, &registry);
 }
 
 void synchronize_rcu(void)
 {
+	CDS_LIST_HEAD(cur_snap_readers);
+	CDS_LIST_HEAD(qsreaders);
 	sigset_t newmask, oldmask;
 	int ret;
 
-	ret = sigemptyset(&newmask);
+	ret = sigfillset(&newmask);
 	assert(!ret);
-	ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+	ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
 	assert(!ret);
 
 	mutex_lock(&rcu_gp_lock);
@@ -221,7 +234,7 @@ void synchronize_rcu(void)
 	/*
 	 * Wait for readers to observe original parity or be quiescent.
 	 */
-	wait_for_readers();
+	wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
 
 	/*
 	 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
@@ -231,7 +244,7 @@ void synchronize_rcu(void)
 	cmm_smp_mb();
 
 	/* Switch parity: 0 -> 1, 1 -> 0 */
-	CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+	CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE);
 
 	/*
 	 * Must commit qparity update to memory before waiting for other parity
@@ -250,7 +263,12 @@ void synchronize_rcu(void)
 	/*
 	 * Wait for readers to observe new parity or be quiescent.
 	 */
-	wait_for_readers();
+	wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
+
+	/*
+	 * Put quiescent reader list back into registry.
+	 */
+	cds_list_splice(&qsreaders, &registry);
 
 	/*
 	 * Finish waiting for reader threads before letting the old ptr being
@@ -277,6 +295,11 @@ void rcu_read_unlock(void)
 	_rcu_read_unlock();
 }
 
+int rcu_read_ongoing(void)
+{
+	return _rcu_read_ongoing();
+}
+
 /*
  * only grow for now.
  */
@@ -362,9 +385,9 @@ void rcu_bp_register(void)
 	sigset_t newmask, oldmask;
 	int ret;
 
-	ret = sigemptyset(&newmask);
+	ret = sigfillset(&newmask);
 	assert(!ret);
-	ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+	ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
 	assert(!ret);
 
 	/*
@@ -397,9 +420,9 @@ void rcu_bp_before_fork(void)
 	sigset_t newmask, oldmask;
 	int ret;
 
-	ret = sigemptyset(&newmask);
+	ret = sigfillset(&newmask);
 	assert(!ret);
-	ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+	ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
 	assert(!ret);
 	mutex_lock(&rcu_gp_lock);
 	saved_fork_signal_mask = oldmask;