Cleanup: urcu: remove unused membarrier "group" parameter

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 6f5b1e01ea04c09db4f7c5c261918750396254ea..1aa00fec9278929996fed4183ebe2acf40d5b61f 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -77,9 +77,10 @@
 # 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 +150,7 @@ 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 +165,17 @@ 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 +218,13 @@ 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 +236,23 @@ 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 +280,7 @@ 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 +310,7 @@ 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 +333,13 @@ 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 +400,7 @@ 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 +461,7 @@ 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 +500,8 @@ 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 +510,8 @@ 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 +519,15 @@ 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