x86: allocate membarrier system call number
[urcu.git] / urcu.c
diff --git a/urcu.c b/urcu.c
index 67a3eb21c8996b0751f9fc1d14ed9d71379f8bf5..a620b762b4796712bd05efb862de8cb6c53c41fd 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -3,7 +3,7 @@
  *
  * Userspace RCU library
  *
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
  *
  * This library is free software; you can redistribute it and/or
  */
 
 #define _BSD_SOURCE
+#define _GNU_SOURCE
+#define _LGPL_SOURCE
+#define _DEFAULT_SOURCE
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
 #include <assert.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <string.h>
 #include <errno.h>
 #include <poll.h>
 
-#include "urcu-static.h"
+#include "urcu/arch.h"
+#include "urcu/wfcqueue.h"
+#include "urcu/map/urcu.h"
+#include "urcu/static/urcu.h"
+#include "urcu-pointer.h"
+#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
 #include "urcu.h"
+#define _LGPL_SOURCE
+
+/*
+ * If a reader is really non-cooperative and refuses to commit its
+ * rcu_active_readers count to memory (there is no barrier in the reader
+ * per-se), kick it after 10 loops waiting for it.
+ */
+#define KICK_READER_LOOPS      10
+
+/*
+ * Active attempts to check for reader Q.S. before calling futex().
+ */
+#define RCU_QS_ACTIVE_ATTEMPTS 100
+
+/* 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
+
+enum membarrier_cmd {
+       MEMBARRIER_CMD_QUERY = 0,
+       MEMBARRIER_CMD_SHARED = (1 << 0),
+};
 
 #ifdef RCU_MEMBARRIER
 static int init_done;
-int has_sys_membarrier;
+int rcu_has_sys_membarrier;
 
 void __attribute__((constructor)) rcu_init(void);
 #endif
@@ -57,91 +96,82 @@ void __attribute__((constructor)) rcu_init(void);
 void __attribute__((destructor)) rcu_exit(void);
 #endif
 
-static pthread_mutex_t rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
-
-int gp_futex;
-
 /*
- * 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.
+ * rcu_gp_lock ensures mutual exclusion between threads calling
+ * synchronize_rcu().
  */
-long rcu_gp_ctr = RCU_GP_COUNT;
+static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
+/*
+ * rcu_registry_lock ensures mutual exclusion between threads
+ * registering and unregistering themselves to/from the registry, and
+ * with threads reading that registry from synchronize_rcu(). However,
+ * this lock is not held all the way through the completion of awaiting
+ * for the grace period. It is sporadically released between iterations
+ * on the registry.
+ * rcu_registry_lock may nest inside rcu_gp_lock.
+ */
+static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
+struct rcu_gp rcu_gp = { .ctr = RCU_GP_COUNT };
 
 /*
  * Written to only by each individual reader. Read by both the reader and the
  * writers.
  */
-struct rcu_reader __thread rcu_reader;
+DEFINE_URCU_TLS(struct rcu_reader, rcu_reader);
 
-#ifdef DEBUG_YIELD
-unsigned int yield_active;
-unsigned int __thread rand_yield;
-#endif
+static CDS_LIST_HEAD(registry);
 
-static 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 internal_rcu_lock(void)
+static void mutex_lock(pthread_mutex_t *mutex)
 {
        int ret;
 
 #ifndef DISTRUST_SIGNALS_EXTREME
-       ret = pthread_mutex_lock(&rcu_mutex);
-       if (ret) {
-               perror("Error in pthread mutex lock");
-               exit(-1);
-       }
+       ret = pthread_mutex_lock(mutex);
+       if (ret)
+               urcu_die(ret);
 #else /* #ifndef DISTRUST_SIGNALS_EXTREME */
-       while ((ret = pthread_mutex_trylock(&rcu_mutex)) != 0) {
-               if (ret != EBUSY && ret != EINTR) {
-                       printf("ret = %d, errno = %d\n", ret, errno);
-                       perror("Error in pthread mutex lock");
-                       exit(-1);
-               }
-               if (rcu_reader.need_mb) {
-                       smp_mb();
-                       rcu_reader.need_mb = 0;
-                       smp_mb();
+       while ((ret = pthread_mutex_trylock(mutex)) != 0) {
+               if (ret != EBUSY && ret != EINTR)
+                       urcu_die(ret);
+               if (CMM_LOAD_SHARED(URCU_TLS(rcu_reader).need_mb)) {
+                       cmm_smp_mb();
+                       _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 */
 }
 
-static void internal_rcu_unlock(void)
+static void mutex_unlock(pthread_mutex_t *mutex)
 {
        int ret;
 
-       ret = pthread_mutex_unlock(&rcu_mutex);
-       if (ret) {
-               perror("Error in pthread mutex unlock");
-               exit(-1);
-       }
-}
-
-/*
- * called with rcu_mutex held.
- */
-static void switch_next_rcu_qparity(void)
-{
-       STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+       ret = pthread_mutex_unlock(mutex);
+       if (ret)
+               urcu_die(ret);
 }
 
 #ifdef RCU_MEMBARRIER
-static void smp_mb_heavy(void)
+static void smp_mb_master(void)
 {
-       if (likely(has_sys_membarrier))
-               membarrier(1);
+       if (caa_likely(rcu_has_sys_membarrier))
+               (void) membarrier(MEMBARRIER_CMD_SHARED, 0);
        else
-               smp_mb();
+               cmm_smp_mb();
 }
 #endif
 
 #ifdef RCU_MB
-static void smp_mb_heavy(void)
+static void smp_mb_master(void)
 {
-       smp_mb();
+       cmm_smp_mb();
 }
 #endif
 
@@ -151,20 +181,19 @@ static void force_mb_all_readers(void)
        struct rcu_reader *index;
 
        /*
-        * Ask for each threads to execute a smp_mb() so we can consider the
+        * Ask for each threads to execute a cmm_smp_mb() so we can consider the
         * compiler barriers around rcu read lock as real memory barriers.
         */
-       if (list_empty(&registry))
+       if (cds_list_empty(&registry))
                return;
        /*
-        * pthread_kill has a smp_mb(). But beware, we assume it performs
+        * pthread_kill has a cmm_smp_mb(). But beware, we assume it performs
         * a cache flush on architectures with non-coherent cache. Let's play
-        * safe and don't assume anything : we use smp_mc() to make sure the
+        * safe and don't assume anything : we use cmm_smp_mc() to make sure the
         * cache flush is enforced.
         */
-       list_for_each_entry(index, &registry, head) {
-               index->need_mb = 1;
-               smp_mc();       /* write need_mb before sending the signal */
+       cds_list_for_each_entry(index, &registry, node) {
+               CMM_STORE_SHARED(index->need_mb, 1);
                pthread_kill(index->tid, SIGRCU);
        }
        /*
@@ -180,16 +209,16 @@ static void force_mb_all_readers(void)
         * relevant bug report.  For Linux kernels, we recommend getting
         * the Linux Test Project (LTP).
         */
-       list_for_each_entry(index, &registry, head) {
-               while (index->need_mb) {
+       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);
                }
        }
-       smp_mb();       /* read ->need_mb before ending the barrier */
+       cmm_smp_mb();   /* read ->need_mb before ending the barrier */
 }
 
-static void smp_mb_heavy(void)
+static void smp_mb_master(void)
 {
        force_mb_all_readers();
 }
@@ -201,156 +230,242 @@ static void smp_mb_heavy(void)
 static void wait_gp(void)
 {
        /* Read reader_gp before read futex */
-       smp_mb_heavy();
-       if (uatomic_read(&gp_futex) == -1)
-               futex_async(&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);
+               }
+       }
 }
 
-void wait_for_quiescent_state(void)
+/*
+ * Always called with rcu_registry lock held. Releases this lock between
+ * iterations and grabs it again. Holds the lock when it returns.
+ */
+static void wait_for_readers(struct cds_list_head *input_readers,
+                       struct cds_list_head *cur_snap_readers,
+                       struct cds_list_head *qsreaders)
 {
-       LIST_HEAD(qsreaders);
-       int wait_loops = 0;
+       unsigned int wait_loops = 0;
        struct rcu_reader *index, *tmp;
+#ifdef HAS_INCOHERENT_CACHES
+       unsigned int wait_gp_loops = 0;
+#endif /* HAS_INCOHERENT_CACHES */
 
-       if (list_empty(&registry))
-               return;
        /*
-        * Wait for each thread rcu_reader.ctr count to become 0.
+        * Wait for each thread URCU_TLS(rcu_reader).ctr to either
+        * indicate quiescence (not nested), or observe the current
+        * rcu_gp.ctr value.
         */
        for (;;) {
-               wait_loops++;
-               if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
-                       uatomic_dec(&gp_futex);
+               if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
+                       wait_loops++;
+               if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+                       uatomic_dec(&rcu_gp.futex);
                        /* Write futex before read reader_gp */
-                       smp_mb_heavy();
+                       smp_mb_master();
                }
 
-               list_for_each_entry_safe(index, tmp, &registry, head) {
-                       if (!rcu_old_gp_ongoing(&index->ctr))
-                               list_move(&index->head, &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;
+                       }
                }
 
 #ifndef HAS_INCOHERENT_CACHES
-               if (list_empty(&registry)) {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+               if (cds_list_empty(input_readers)) {
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                                /* Read reader_gp before write futex */
-                               smp_mb_heavy();
-                               uatomic_set(&gp_futex, 0);
+                               smp_mb_master();
+                               uatomic_set(&rcu_gp.futex, 0);
                        }
                        break;
                } else {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS)
+                       /* Temporarily unlock the registry lock. */
+                       mutex_unlock(&rcu_registry_lock);
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
                                wait_gp();
                        else
-                               cpu_relax();
+                               caa_cpu_relax();
+                       /* Re-lock the registry lock before the next loop. */
+                       mutex_lock(&rcu_registry_lock);
                }
 #else /* #ifndef HAS_INCOHERENT_CACHES */
                /*
                 * BUSY-LOOP. Force the reader thread to commit its
-                * rcu_reader.ctr update to memory if we wait for too long.
+                * URCU_TLS(rcu_reader).ctr update to memory if we wait
+                * for too long.
                 */
-               if (list_empty(&registry)) {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+               if (cds_list_empty(input_readers)) {
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                                /* Read reader_gp before write futex */
-                               smp_mb_heavy();
-                               uatomic_set(&gp_futex, 0);
+                               smp_mb_master();
+                               uatomic_set(&rcu_gp.futex, 0);
                        }
                        break;
                } else {
-                       switch (wait_loops) {
-                       case RCU_QS_ACTIVE_ATTEMPTS:
+                       if (wait_gp_loops == KICK_READER_LOOPS) {
+                               smp_mb_master();
+                               wait_gp_loops = 0;
+                       }
+                       /* Temporarily unlock the registry lock. */
+                       mutex_unlock(&rcu_registry_lock);
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                                wait_gp();
-                               break; /* only escape switch */
-                       case KICK_READER_LOOPS:
-                               smp_mb_heavy();
-                               wait_loops = 0;
-                               break; /* only escape switch */
-                       default:
-                               cpu_relax();
+                               wait_gp_loops++;
+                       } else {
+                               caa_cpu_relax();
                        }
+                       /* Re-lock the registry lock before the next loop. */
+                       mutex_lock(&rcu_registry_lock);
                }
 #endif /* #else #ifndef HAS_INCOHERENT_CACHES */
        }
-       /* put back the reader list in the registry */
-       list_splice(&qsreaders, &registry);
 }
 
 void synchronize_rcu(void)
 {
-       internal_rcu_lock();
+       CDS_LIST_HEAD(cur_snap_readers);
+       CDS_LIST_HEAD(qsreaders);
+       DEFINE_URCU_WAIT_NODE(wait, URCU_WAIT_WAITING);
+       struct urcu_waiters waiters;
 
-       /* All threads should read qparity before accessing data structure
-        * where new ptr points to. Must be done within internal_rcu_lock
-        * because it iterates on reader threads.*/
-       /* Write new ptr before changing the qparity */
-       smp_mb_heavy();
+       /*
+        * 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.
+        * The implicit memory barrier before urcu_wait_add()
+        * orders prior memory accesses of threads put into the wait
+        * queue before their insertion into the wait queue.
+        */
+       if (urcu_wait_add(&gp_waiters, &wait) != 0) {
+               /* Not first in queue: will be awakened by another thread. */
+               urcu_adaptative_busy_wait(&wait);
+               /* Order following memory accesses after grace period. */
+               cmm_smp_mb();
+               return;
+       }
+       /* We won't need to wake ourself up */
+       urcu_wait_set_state(&wait, URCU_WAIT_RUNNING);
 
-       switch_next_rcu_qparity();      /* 0 -> 1 */
+       mutex_lock(&rcu_gp_lock);
 
        /*
-        * Must commit qparity update to memory before waiting for parity
-        * 0 quiescent state. Failure to do so could result in the writer
-        * waiting forever while new readers are always accessing data (no
-        * progress).
-        * Ensured by STORE_SHARED and LOAD_SHARED.
+        * Move all waiters into our local queue.
         */
+       urcu_move_waiters(&waiters, &gp_waiters);
+
+       mutex_lock(&rcu_registry_lock);
+
+       if (cds_list_empty(&registry))
+               goto out;
 
        /*
-        * Adding a smp_mb() which is _not_ formally required, but makes the
-        * model easier to understand. It does not have a big performance impact
-        * anyway, given this is the write-side.
+        * All threads should read qparity before accessing data structure
+        * where new ptr points to. Must be done within rcu_registry_lock
+        * because it iterates on reader threads.
         */
-       smp_mb();
+       /* Write new ptr before changing the qparity */
+       smp_mb_master();
 
        /*
-        * Wait for previous parity to be empty of readers.
+        * Wait for readers to observe original parity or be quiescent.
+        * wait_for_readers() can release and grab again rcu_registry_lock
+        * interally.
         */
-       wait_for_quiescent_state();     /* Wait readers in parity 0 */
+       wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
 
        /*
-        * Must finish waiting for quiescent state for parity 0 before
-        * committing qparity update to memory. Failure to do so could result in
-        * the writer waiting forever while new readers are always accessing
-        * data (no progress).
-        * Ensured by STORE_SHARED and LOAD_SHARED.
+        * Must finish waiting for quiescent state for original parity before
+        * committing next rcu_gp.ctr update to memory. Failure to do so could
+        * result in the writer waiting forever while new readers are always
+        * accessing data (no progress).  Enforce compiler-order of load
+        * URCU_TLS(rcu_reader).ctr before store to rcu_gp.ctr.
         */
+       cmm_barrier();
 
        /*
-        * Adding a smp_mb() which is _not_ formally required, but makes the
+        * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
         * model easier to understand. It does not have a big performance impact
         * anyway, given this is the write-side.
         */
-       smp_mb();
+       cmm_smp_mb();
 
-       switch_next_rcu_qparity();      /* 1 -> 0 */
+       /* Switch parity: 0 -> 1, 1 -> 0 */
+       CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE);
 
        /*
-        * Must commit qparity update to memory before waiting for parity
-        * 1 quiescent state. Failure to do so could result in the writer
-        * waiting forever while new readers are always accessing data (no
-        * progress).
-        * Ensured by STORE_SHARED and LOAD_SHARED.
+        * Must commit rcu_gp.ctr update to memory before waiting for quiescent
+        * state. Failure to do so could result in the writer waiting forever
+        * while new readers are always accessing data (no progress). Enforce
+        * compiler-order of store to rcu_gp.ctr before load rcu_reader ctr.
         */
+       cmm_barrier();
 
        /*
-        * Adding a smp_mb() which is _not_ formally required, but makes the
+        *
+        * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
         * model easier to understand. It does not have a big performance impact
         * anyway, given this is the write-side.
         */
-       smp_mb();
+       cmm_smp_mb();
+
+       /*
+        * Wait for readers to observe new parity or be quiescent.
+        * wait_for_readers() can release and grab again rcu_registry_lock
+        * interally.
+        */
+       wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
 
        /*
-        * Wait for previous parity to be empty of readers.
+        * Put quiescent reader list back into registry.
         */
-       wait_for_quiescent_state();     /* Wait readers in parity 1 */
+       cds_list_splice(&qsreaders, &registry);
 
-       /* Finish waiting for reader threads before letting the old ptr being
-        * freed. Must be done within internal_rcu_lock because it iterates on
-        * reader threads. */
-       smp_mb_heavy();
+       /*
+        * Finish waiting for reader threads before letting the old ptr
+        * being freed. Must be done within rcu_registry_lock because it
+        * iterates on reader threads.
+        */
+       smp_mb_master();
+out:
+       mutex_unlock(&rcu_registry_lock);
+       mutex_unlock(&rcu_gp_lock);
 
-       internal_rcu_unlock();
+       /*
+        * Wakeup waiters only after we have completed the grace period
+        * and have ensured the memory barriers at the end of the grace
+        * period have been issued.
+        */
+       urcu_wake_all_waiters(&waiters);
 }
 
 /*
@@ -367,33 +482,46 @@ void rcu_read_unlock(void)
        _rcu_read_unlock();
 }
 
+int rcu_read_ongoing(void)
+{
+       return _rcu_read_ongoing();
+}
+
 void rcu_register_thread(void)
 {
-       rcu_reader.tid = pthread_self();
-       assert(rcu_reader.need_mb == 0);
-       assert(rcu_reader.ctr == 0);
+       URCU_TLS(rcu_reader).tid = pthread_self();
+       assert(URCU_TLS(rcu_reader).need_mb == 0);
+       assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK));
 
-       internal_rcu_lock();
+       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 */
-       list_add(&rcu_reader.head, &registry);
-       internal_rcu_unlock();
+       cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
+       mutex_unlock(&rcu_registry_lock);
 }
 
 void rcu_unregister_thread(void)
 {
-       internal_rcu_lock();
-       list_del(&rcu_reader.head);
-       internal_rcu_unlock();
+       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);
 }
 
 #ifdef RCU_MEMBARRIER
 void rcu_init(void)
 {
+       int ret;
+
        if (init_done)
                return;
        init_done = 1;
-       if (!membarrier(1))
-               has_sys_membarrier = 1;
+       ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
+       if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
+               rcu_has_sys_membarrier = 1;
+       }
 }
 #endif
 
@@ -401,22 +529,22 @@ void rcu_init(void)
 static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
 {
        /*
-        * Executing this smp_mb() is the only purpose of this signal handler.
-        * It punctually promotes barrier() into smp_mb() on every thread it is
+        * Executing this cmm_smp_mb() is the only purpose of this signal handler.
+        * It punctually promotes cmm_barrier() into cmm_smp_mb() on every thread it is
         * executed on.
         */
-       smp_mb();
-       rcu_reader.need_mb = 0;
-       smp_mb();
+       cmm_smp_mb();
+       _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
+       cmm_smp_mb();
 }
 
 /*
  * rcu_init constructor. Called when the library is linked, but also when
  * reader threads are calling rcu_register_thread().
  * Should only be called by a single thread at a given time. This is ensured by
- * holing the internal_rcu_lock() from rcu_register_thread() or by running at
- * library load time, which should not be executed by multiple threads nor
- * concurrently with rcu_register_thread() anyway.
+ * holing the rcu_registry_lock from rcu_register_thread() or by running
+ * at library load time, which should not be executed by multiple
+ * threads nor concurrently with rcu_register_thread() anyway.
  */
 void rcu_init(void)
 {
@@ -431,23 +559,25 @@ void rcu_init(void)
        act.sa_flags = SA_SIGINFO | SA_RESTART;
        sigemptyset(&act.sa_mask);
        ret = sigaction(SIGRCU, &act, NULL);
-       if (ret) {
-               perror("Error in sigaction");
-               exit(-1);
-       }
+       if (ret)
+               urcu_die(errno);
 }
 
 void rcu_exit(void)
 {
-       struct sigaction act;
-       int ret;
-
-       ret = sigaction(SIGRCU, NULL, &act);
-       if (ret) {
-               perror("Error in sigaction");
-               exit(-1);
-       }
-       assert(act.sa_sigaction == sigrcu_handler);
-       assert(list_empty(&registry));
+       /*
+        * Don't unregister the SIGRCU signal handler anymore, because
+        * call_rcu threads could still be using it shortly before the
+        * application exits.
+        * Assertion disabled because call_rcu threads are now rcu
+        * readers, and left running at exit.
+        * assert(cds_list_empty(&registry));
+        */
 }
+
 #endif /* #ifdef RCU_SIGNAL */
+
+DEFINE_RCU_FLAVOR(rcu_flavor);
+
+#include "urcu-call-rcu-impl.h"
+#include "urcu-defer-impl.h"
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