X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=a620b762b4796712bd05efb862de8cb6c53c41fd;hp=6f5b1e01ea04c09db4f7c5c261918750396254ea;hb=999991c6e4600c410181baea65bda9f406464872;hpb=82d50e1adc21b8f41e5c51ff0e84db5348bdff7f

diff --git a/urcu.c b/urcu.c
index 6f5b1e0..a620b76 100644
--- a/urcu.c
+++ b/urcu.c
@@ -37,6 +37,7 @@
 #include <errno.h>
 #include <poll.h>
 
+#include "urcu/arch.h"
 #include "urcu/wfcqueue.h"
 #include "urcu/map/urcu.h"
 #include "urcu/static/urcu.h"
@@ -63,23 +64,17 @@
  */
 #define RCU_QS_ACTIVE_ATTEMPTS 100
 
-/*
- * RCU_MEMBARRIER is only possibly available on Linux.
- */
-#if defined(RCU_MEMBARRIER) && defined(__linux__)
-#include <urcu/syscall-compat.h>
-#endif
-
-/* If the headers do not support SYS_membarrier, fall back on RCU_MB */
-#ifdef SYS_membarrier
-# define membarrier(...)		syscall(SYS_membarrier, __VA_ARGS__)
+/* If the headers do not support membarrier system call, fall back on RCU_MB */
+#ifdef __NR_membarrier
+# define membarrier(...)		syscall(__NR_membarrier, __VA_ARGS__)
 #else
 # define membarrier(...)		-ENOSYS
 #endif
 
-#define MEMBARRIER_EXPEDITED		(1 << 0)
-#define MEMBARRIER_DELAYED		(1 << 1)
-#define MEMBARRIER_QUERY		(1 << 16)
+enum membarrier_cmd {
+	MEMBARRIER_CMD_QUERY = 0,
+	MEMBARRIER_CMD_SHARED = (1 << 0),
+};
 
 #ifdef RCU_MEMBARRIER
 static int init_done;
@@ -149,7 +144,7 @@ static void mutex_lock(pthread_mutex_t *mutex)
 			_CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
 			cmm_smp_mb();
 		}
-		poll(NULL,0,10);
+		(void) poll(NULL, 0, 10);
 	}
 #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
 }
@@ -164,17 +159,17 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 }
 
 #ifdef RCU_MEMBARRIER
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	if (caa_likely(rcu_has_sys_membarrier))
-		(void) membarrier(MEMBARRIER_EXPEDITED);
+		(void) membarrier(MEMBARRIER_CMD_SHARED, 0);
 	else
 		cmm_smp_mb();
 }
 #endif
 
 #ifdef RCU_MB
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	cmm_smp_mb();
 }
@@ -217,13 +212,13 @@ static void force_mb_all_readers(void)
 	cds_list_for_each_entry(index, &registry, node) {
 		while (CMM_LOAD_SHARED(index->need_mb)) {
 			pthread_kill(index->tid, SIGRCU);
-			poll(NULL, 0, 1);
+			(void) poll(NULL, 0, 1);
 		}
 	}
 	cmm_smp_mb();	/* read ->need_mb before ending the barrier */
 }
 
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
 {
 	force_mb_all_readers();
 }
@@ -235,10 +230,23 @@ static void smp_mb_master(int group)
 static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
-	smp_mb_master(RCU_MB_GROUP);
-	if (uatomic_read(&rcu_gp.futex) == -1)
-		futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
-		      NULL, NULL, 0);
+	smp_mb_master();
+	if (uatomic_read(&rcu_gp.futex) != -1)
+		return;
+	while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
+			NULL, NULL, 0)) {
+		switch (errno) {
+		case EWOULDBLOCK:
+			/* Value already changed. */
+			return;
+		case EINTR:
+			/* Retry if interrupted by signal. */
+			break;	/* Get out of switch. */
+		default:
+			/* Unexpected error. */
+			urcu_die(errno);
+		}
+	}
 }
 
 /*
@@ -266,7 +274,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 			uatomic_dec(&rcu_gp.futex);
 			/* Write futex before read reader_gp */
-			smp_mb_master(RCU_MB_GROUP);
+			smp_mb_master();
 		}
 
 		cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
@@ -296,7 +304,7 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (cds_list_empty(input_readers)) {
 			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				uatomic_set(&rcu_gp.futex, 0);
 			}
 			break;
@@ -319,13 +327,13 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 		if (cds_list_empty(input_readers)) {
 			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				uatomic_set(&rcu_gp.futex, 0);
 			}
 			break;
 		} else {
 			if (wait_gp_loops == KICK_READER_LOOPS) {
-				smp_mb_master(RCU_MB_GROUP);
+				smp_mb_master();
 				wait_gp_loops = 0;
 			}
 			/* Temporarily unlock the registry lock. */
@@ -386,7 +394,7 @@ void synchronize_rcu(void)
 	 * because it iterates on reader threads.
 	 */
 	/* Write new ptr before changing the qparity */
-	smp_mb_master(RCU_MB_GROUP);
+	smp_mb_master();
 
 	/*
 	 * Wait for readers to observe original parity or be quiescent.
@@ -447,7 +455,7 @@ void synchronize_rcu(void)
 	 * being freed. Must be done within rcu_registry_lock because it
 	 * iterates on reader threads.
 	 */
-	smp_mb_master(RCU_MB_GROUP);
+	smp_mb_master();
 out:
 	mutex_unlock(&rcu_registry_lock);
 	mutex_unlock(&rcu_gp_lock);
@@ -486,6 +494,8 @@ void rcu_register_thread(void)
 	assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK));
 
 	mutex_lock(&rcu_registry_lock);
+	assert(!URCU_TLS(rcu_reader).registered);
+	URCU_TLS(rcu_reader).registered = 1;
 	rcu_init();	/* In case gcc does not support constructor attribute */
 	cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
 	mutex_unlock(&rcu_registry_lock);
@@ -494,6 +504,8 @@ void rcu_register_thread(void)
 void rcu_unregister_thread(void)
 {
 	mutex_lock(&rcu_registry_lock);
+	assert(URCU_TLS(rcu_reader).registered);
+	URCU_TLS(rcu_reader).registered = 0;
 	cds_list_del(&URCU_TLS(rcu_reader).node);
 	mutex_unlock(&rcu_registry_lock);
 }
@@ -501,11 +513,15 @@ void rcu_unregister_thread(void)
 #ifdef RCU_MEMBARRIER
 void rcu_init(void)
 {
+	int ret;
+
 	if (init_done)
 		return;
 	init_done = 1;
-	if (!membarrier(MEMBARRIER_EXPEDITED | MEMBARRIER_QUERY))
+	ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
+	if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
 		rcu_has_sys_membarrier = 1;
+	}
 }
 #endif