+++ /dev/null
-/*
- * urcu-call-rcu.c
- *
- * Userspace RCU library - batch memory reclamation with kernel API
- *
- * Copyright (c) 2010 Paul E. McKenney <paulmck@linux.vnet.ibm.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#define _GNU_SOURCE
-#define _LGPL_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 <sys/time.h>
-#include <unistd.h>
-#include <sched.h>
-
-#include "config.h"
-#include "compat-getcpu.h"
-#include "urcu/wfcqueue.h"
-#include "urcu-call-rcu.h"
-#include "urcu-pointer.h"
-#include "urcu/list.h"
-#include "urcu/futex.h"
-#include "urcu/tls-compat.h"
-#include "urcu/ref.h"
-#include "urcu-die.h"
-
-#define SET_AFFINITY_CHECK_PERIOD (1U << 8) /* 256 */
-#define SET_AFFINITY_CHECK_PERIOD_MASK (SET_AFFINITY_CHECK_PERIOD - 1)
-
-/* Data structure that identifies a call_rcu thread. */
-
-struct call_rcu_data {
- /*
- * We do not align head on a different cache-line than tail
- * mainly because call_rcu callback-invocation threads use
- * batching ("splice") to get an entire list of callbacks, which
- * effectively empties the queue, and requires to touch the tail
- * anyway.
- */
- struct cds_wfcq_tail cbs_tail;
- struct cds_wfcq_head cbs_head;
- unsigned long flags;
- int32_t futex;
- unsigned long qlen; /* maintained for debugging. */
- pthread_t tid;
- int cpu_affinity;
- unsigned long gp_count;
- struct cds_list_head list;
-} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
-
-struct call_rcu_completion {
- int barrier_count;
- int32_t futex;
- struct urcu_ref ref;
-};
-
-struct call_rcu_completion_work {
- struct rcu_head head;
- struct call_rcu_completion *completion;
-};
-
-/*
- * List of all call_rcu_data structures to keep valgrind happy.
- * Protected by call_rcu_mutex.
- */
-
-static CDS_LIST_HEAD(call_rcu_data_list);
-
-/* Link a thread using call_rcu() to its call_rcu thread. */
-
-static DEFINE_URCU_TLS(struct call_rcu_data *, thread_call_rcu_data);
-
-/*
- * Guard call_rcu thread creation and atfork handlers.
- */
-static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
-
-/* If a given thread does not have its own call_rcu thread, this is default. */
-
-static struct call_rcu_data *default_call_rcu_data;
-
-/*
- * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
- * available, then we can have call_rcu threads assigned to individual
- * CPUs rather than only to specific threads.
- */
-
-#if defined(HAVE_SYSCONF) && (defined(HAVE_SCHED_GETCPU) || defined(HAVE_GETCPUID))
-
-/*
- * Pointer to array of pointers to per-CPU call_rcu_data structures
- * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an
- * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a
- * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer
- * without mutex. The call_rcu_mutex protects updates.
- */
-
-static struct call_rcu_data **per_cpu_call_rcu_data;
-static long maxcpus;
-
-static void maxcpus_reset(void)
-{
- maxcpus = 0;
-}
-
-/* Allocate the array if it has not already been allocated. */
-
-static void alloc_cpu_call_rcu_data(void)
-{
- struct call_rcu_data **p;
- static int warned = 0;
-
- if (maxcpus != 0)
- return;
- maxcpus = sysconf(_SC_NPROCESSORS_CONF);
- if (maxcpus <= 0) {
- return;
- }
- p = malloc(maxcpus * sizeof(*per_cpu_call_rcu_data));
- if (p != NULL) {
- memset(p, '\0', maxcpus * sizeof(*per_cpu_call_rcu_data));
- rcu_set_pointer(&per_cpu_call_rcu_data, p);
- } else {
- if (!warned) {
- fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n");
- }
- warned = 1;
- }
-}
-
-#else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
-
-/*
- * per_cpu_call_rcu_data should be constant, but some functions below, used both
- * for cases where cpu number is available and not available, assume it it not
- * constant.
- */
-static struct call_rcu_data **per_cpu_call_rcu_data = NULL;
-static const long maxcpus = -1;
-
-static void maxcpus_reset(void)
-{
-}
-
-static void alloc_cpu_call_rcu_data(void)
-{
-}
-
-#endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
-
-/* Acquire the specified pthread mutex. */
-
-static void call_rcu_lock(pthread_mutex_t *pmp)
-{
- int ret;
-
- ret = pthread_mutex_lock(pmp);
- if (ret)
- urcu_die(ret);
-}
-
-/* Release the specified pthread mutex. */
-
-static void call_rcu_unlock(pthread_mutex_t *pmp)
-{
- int ret;
-
- ret = pthread_mutex_unlock(pmp);
- if (ret)
- urcu_die(ret);
-}
-
-/*
- * Periodically retry setting CPU affinity if we migrate.
- * Losing affinity can be caused by CPU hotunplug/hotplug, or by
- * cpuset(7).
- */
-#if HAVE_SCHED_SETAFFINITY
-static
-int set_thread_cpu_affinity(struct call_rcu_data *crdp)
-{
- cpu_set_t mask;
- int ret;
-
- if (crdp->cpu_affinity < 0)
- return 0;
- if (++crdp->gp_count & SET_AFFINITY_CHECK_PERIOD_MASK)
- return 0;
- if (urcu_sched_getcpu() == crdp->cpu_affinity)
- return 0;
-
- CPU_ZERO(&mask);
- CPU_SET(crdp->cpu_affinity, &mask);
-#if SCHED_SETAFFINITY_ARGS == 2
- ret = sched_setaffinity(0, &mask);
-#else
- ret = sched_setaffinity(0, sizeof(mask), &mask);
-#endif
- /*
- * EINVAL is fine: can be caused by hotunplugged CPUs, or by
- * cpuset(7). This is why we should always retry if we detect
- * migration.
- */
- if (ret && errno == EINVAL) {
- ret = 0;
- errno = 0;
- }
- return ret;
-}
-#else
-static
-int set_thread_cpu_affinity(struct call_rcu_data *crdp)
-{
- return 0;
-}
-#endif
-
-static void call_rcu_wait(struct call_rcu_data *crdp)
-{
- /* Read call_rcu list before read futex */
- cmm_smp_mb();
- if (uatomic_read(&crdp->futex) != -1)
- return;
- while (futex_async(&crdp->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);
- }
- }
-}
-
-static void call_rcu_wake_up(struct call_rcu_data *crdp)
-{
- /* Write to call_rcu list before reading/writing futex */
- cmm_smp_mb();
- if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) {
- uatomic_set(&crdp->futex, 0);
- if (futex_async(&crdp->futex, FUTEX_WAKE, 1,
- NULL, NULL, 0) < 0)
- urcu_die(errno);
- }
-}
-
-static void call_rcu_completion_wait(struct call_rcu_completion *completion)
-{
- /* Read completion barrier count before read futex */
- cmm_smp_mb();
- if (uatomic_read(&completion->futex) != -1)
- return;
- while (futex_async(&completion->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);
- }
- }
-}
-
-static void call_rcu_completion_wake_up(struct call_rcu_completion *completion)
-{
- /* Write to completion barrier count before reading/writing futex */
- cmm_smp_mb();
- if (caa_unlikely(uatomic_read(&completion->futex) == -1)) {
- uatomic_set(&completion->futex, 0);
- if (futex_async(&completion->futex, FUTEX_WAKE, 1,
- NULL, NULL, 0) < 0)
- urcu_die(errno);
- }
-}
-
-/* This is the code run by each call_rcu thread. */
-
-static void *call_rcu_thread(void *arg)
-{
- unsigned long cbcount;
- struct call_rcu_data *crdp = (struct call_rcu_data *) arg;
- int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT);
-
- if (set_thread_cpu_affinity(crdp))
- urcu_die(errno);
-
- /*
- * If callbacks take a read-side lock, we need to be registered.
- */
- rcu_register_thread();
-
- URCU_TLS(thread_call_rcu_data) = crdp;
- if (!rt) {
- uatomic_dec(&crdp->futex);
- /* Decrement futex before reading call_rcu list */
- cmm_smp_mb();
- }
- for (;;) {
- struct cds_wfcq_head cbs_tmp_head;
- struct cds_wfcq_tail cbs_tmp_tail;
- struct cds_wfcq_node *cbs, *cbs_tmp_n;
- enum cds_wfcq_ret splice_ret;
-
- if (set_thread_cpu_affinity(crdp))
- urcu_die(errno);
-
- if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) {
- /*
- * Pause requested. Become quiescent: remove
- * ourself from all global lists, and don't
- * process any callback. The callback lists may
- * still be non-empty though.
- */
- rcu_unregister_thread();
- cmm_smp_mb__before_uatomic_or();
- uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED);
- while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0)
- (void) poll(NULL, 0, 1);
- uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED);
- cmm_smp_mb__after_uatomic_and();
- rcu_register_thread();
- }
-
- cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail);
- splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head,
- &cbs_tmp_tail, &crdp->cbs_head, &crdp->cbs_tail);
- assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
- assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
- if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) {
- synchronize_rcu();
- cbcount = 0;
- __cds_wfcq_for_each_blocking_safe(&cbs_tmp_head,
- &cbs_tmp_tail, cbs, cbs_tmp_n) {
- struct rcu_head *rhp;
-
- rhp = caa_container_of(cbs,
- struct rcu_head, next);
- rhp->func(rhp);
- cbcount++;
- }
- uatomic_sub(&crdp->qlen, cbcount);
- }
- if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP)
- break;
- rcu_thread_offline();
- if (!rt) {
- if (cds_wfcq_empty(&crdp->cbs_head,
- &crdp->cbs_tail)) {
- call_rcu_wait(crdp);
- (void) poll(NULL, 0, 10);
- uatomic_dec(&crdp->futex);
- /*
- * Decrement futex before reading
- * call_rcu list.
- */
- cmm_smp_mb();
- } else {
- (void) poll(NULL, 0, 10);
- }
- } else {
- (void) poll(NULL, 0, 10);
- }
- rcu_thread_online();
- }
- if (!rt) {
- /*
- * Read call_rcu list before write futex.
- */
- cmm_smp_mb();
- uatomic_set(&crdp->futex, 0);
- }
- uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED);
- rcu_unregister_thread();
- return NULL;
-}
-
-/*
- * Create both a call_rcu thread and the corresponding call_rcu_data
- * structure, linking the structure in as specified. Caller must hold
- * call_rcu_mutex.
- */
-
-static void call_rcu_data_init(struct call_rcu_data **crdpp,
- unsigned long flags,
- int cpu_affinity)
-{
- struct call_rcu_data *crdp;
- int ret;
-
- crdp = malloc(sizeof(*crdp));
- if (crdp == NULL)
- urcu_die(errno);
- memset(crdp, '\0', sizeof(*crdp));
- cds_wfcq_init(&crdp->cbs_head, &crdp->cbs_tail);
- crdp->qlen = 0;
- crdp->futex = 0;
- crdp->flags = flags;
- cds_list_add(&crdp->list, &call_rcu_data_list);
- crdp->cpu_affinity = cpu_affinity;
- crdp->gp_count = 0;
- cmm_smp_mb(); /* Structure initialized before pointer is planted. */
- *crdpp = crdp;
- ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp);
- if (ret)
- urcu_die(ret);
-}
-
-/*
- * Return a pointer to the call_rcu_data structure for the specified
- * CPU, returning NULL if there is none. We cannot automatically
- * created it because the platform we are running on might not define
- * urcu_sched_getcpu().
- *
- * The call to this function and use of the returned call_rcu_data
- * should be protected by RCU read-side lock.
- */
-
-struct call_rcu_data *get_cpu_call_rcu_data(int cpu)
-{
- static int warned = 0;
- struct call_rcu_data **pcpu_crdp;
-
- pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data);
- if (pcpu_crdp == NULL)
- return NULL;
- if (!warned && maxcpus > 0 && (cpu < 0 || maxcpus <= cpu)) {
- fprintf(stderr, "[error] liburcu: get CPU # out of range\n");
- warned = 1;
- }
- if (cpu < 0 || maxcpus <= cpu)
- return NULL;
- return rcu_dereference(pcpu_crdp[cpu]);
-}
-
-/*
- * Return the tid corresponding to the call_rcu thread whose
- * call_rcu_data structure is specified.
- */
-
-pthread_t get_call_rcu_thread(struct call_rcu_data *crdp)
-{
- return crdp->tid;
-}
-
-/*
- * Create a call_rcu_data structure (with thread) and return a pointer.
- */
-
-static struct call_rcu_data *__create_call_rcu_data(unsigned long flags,
- int cpu_affinity)
-{
- struct call_rcu_data *crdp;
-
- call_rcu_data_init(&crdp, flags, cpu_affinity);
- return crdp;
-}
-
-struct call_rcu_data *create_call_rcu_data(unsigned long flags,
- int cpu_affinity)
-{
- struct call_rcu_data *crdp;
-
- call_rcu_lock(&call_rcu_mutex);
- crdp = __create_call_rcu_data(flags, cpu_affinity);
- call_rcu_unlock(&call_rcu_mutex);
- return crdp;
-}
-
-/*
- * Set the specified CPU to use the specified call_rcu_data structure.
- *
- * Use NULL to remove a CPU's call_rcu_data structure, but it is
- * the caller's responsibility to dispose of the removed structure.
- * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure
- * (prior to NULLing it out, of course).
- *
- * The caller must wait for a grace-period to pass between return from
- * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
- * previous call rcu data as argument.
- */
-
-int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp)
-{
- static int warned = 0;
-
- call_rcu_lock(&call_rcu_mutex);
- alloc_cpu_call_rcu_data();
- if (cpu < 0 || maxcpus <= cpu) {
- if (!warned) {
- fprintf(stderr, "[error] liburcu: set CPU # out of range\n");
- warned = 1;
- }
- call_rcu_unlock(&call_rcu_mutex);
- errno = EINVAL;
- return -EINVAL;
- }
-
- if (per_cpu_call_rcu_data == NULL) {
- call_rcu_unlock(&call_rcu_mutex);
- errno = ENOMEM;
- return -ENOMEM;
- }
-
- if (per_cpu_call_rcu_data[cpu] != NULL && crdp != NULL) {
- call_rcu_unlock(&call_rcu_mutex);
- errno = EEXIST;
- return -EEXIST;
- }
-
- rcu_set_pointer(&per_cpu_call_rcu_data[cpu], crdp);
- call_rcu_unlock(&call_rcu_mutex);
- return 0;
-}
-
-/*
- * Return a pointer to the default call_rcu_data structure, creating
- * one if need be. Because we never free call_rcu_data structures,
- * we don't need to be in an RCU read-side critical section.
- */
-
-struct call_rcu_data *get_default_call_rcu_data(void)
-{
- if (default_call_rcu_data != NULL)
- return rcu_dereference(default_call_rcu_data);
- call_rcu_lock(&call_rcu_mutex);
- if (default_call_rcu_data != NULL) {
- call_rcu_unlock(&call_rcu_mutex);
- return default_call_rcu_data;
- }
- call_rcu_data_init(&default_call_rcu_data, 0, -1);
- call_rcu_unlock(&call_rcu_mutex);
- return default_call_rcu_data;
-}
-
-/*
- * Return the call_rcu_data structure that applies to the currently
- * running thread. Any call_rcu_data structure assigned specifically
- * to this thread has first priority, followed by any call_rcu_data
- * structure assigned to the CPU on which the thread is running,
- * followed by the default call_rcu_data structure. If there is not
- * yet a default call_rcu_data structure, one will be created.
- *
- * Calls to this function and use of the returned call_rcu_data should
- * be protected by RCU read-side lock.
- */
-struct call_rcu_data *get_call_rcu_data(void)
-{
- struct call_rcu_data *crd;
-
- if (URCU_TLS(thread_call_rcu_data) != NULL)
- return URCU_TLS(thread_call_rcu_data);
-
- if (maxcpus > 0) {
- crd = get_cpu_call_rcu_data(urcu_sched_getcpu());
- if (crd)
- return crd;
- }
-
- return get_default_call_rcu_data();
-}
-
-/*
- * Return a pointer to this task's call_rcu_data if there is one.
- */
-
-struct call_rcu_data *get_thread_call_rcu_data(void)
-{
- return URCU_TLS(thread_call_rcu_data);
-}
-
-/*
- * Set this task's call_rcu_data structure as specified, regardless
- * of whether or not this task already had one. (This allows switching
- * to and from real-time call_rcu threads, for example.)
- *
- * Use NULL to remove a thread's call_rcu_data structure, but it is
- * the caller's responsibility to dispose of the removed structure.
- * Use get_thread_call_rcu_data() to obtain a pointer to the old structure
- * (prior to NULLing it out, of course).
- */
-
-void set_thread_call_rcu_data(struct call_rcu_data *crdp)
-{
- URCU_TLS(thread_call_rcu_data) = crdp;
-}
-
-/*
- * Create a separate call_rcu thread for each CPU. This does not
- * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data()
- * function if you want that behavior. Should be paired with
- * free_all_cpu_call_rcu_data() to teardown these call_rcu worker
- * threads.
- */
-
-int create_all_cpu_call_rcu_data(unsigned long flags)
-{
- int i;
- struct call_rcu_data *crdp;
- int ret;
-
- call_rcu_lock(&call_rcu_mutex);
- alloc_cpu_call_rcu_data();
- call_rcu_unlock(&call_rcu_mutex);
- if (maxcpus <= 0) {
- errno = EINVAL;
- return -EINVAL;
- }
- if (per_cpu_call_rcu_data == NULL) {
- errno = ENOMEM;
- return -ENOMEM;
- }
- for (i = 0; i < maxcpus; i++) {
- call_rcu_lock(&call_rcu_mutex);
- if (get_cpu_call_rcu_data(i)) {
- call_rcu_unlock(&call_rcu_mutex);
- continue;
- }
- crdp = __create_call_rcu_data(flags, i);
- if (crdp == NULL) {
- call_rcu_unlock(&call_rcu_mutex);
- errno = ENOMEM;
- return -ENOMEM;
- }
- call_rcu_unlock(&call_rcu_mutex);
- if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) {
- call_rcu_data_free(crdp);
-
- /* it has been created by other thread */
- if (ret == -EEXIST)
- continue;
-
- return ret;
- }
- }
- return 0;
-}
-
-/*
- * Wake up the call_rcu thread corresponding to the specified
- * call_rcu_data structure.
- */
-static void wake_call_rcu_thread(struct call_rcu_data *crdp)
-{
- if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT))
- call_rcu_wake_up(crdp);
-}
-
-static void _call_rcu(struct rcu_head *head,
- void (*func)(struct rcu_head *head),
- struct call_rcu_data *crdp)
-{
- cds_wfcq_node_init(&head->next);
- head->func = func;
- cds_wfcq_enqueue(&crdp->cbs_head, &crdp->cbs_tail, &head->next);
- uatomic_inc(&crdp->qlen);
- wake_call_rcu_thread(crdp);
-}
-
-/*
- * Schedule a function to be invoked after a following grace period.
- * This is the only function that must be called -- the others are
- * only present to allow applications to tune their use of RCU for
- * maximum performance.
- *
- * Note that unless a call_rcu thread has not already been created,
- * the first invocation of call_rcu() will create one. So, if you
- * need the first invocation of call_rcu() to be fast, make sure
- * to create a call_rcu thread first. One way to accomplish this is
- * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data().
- *
- * call_rcu must be called by registered RCU read-side threads.
- */
-void call_rcu(struct rcu_head *head,
- void (*func)(struct rcu_head *head))
-{
- struct call_rcu_data *crdp;
-
- /* Holding rcu read-side lock across use of per-cpu crdp */
- _rcu_read_lock();
- crdp = get_call_rcu_data();
- _call_rcu(head, func, crdp);
- _rcu_read_unlock();
-}
-
-/*
- * Free up the specified call_rcu_data structure, terminating the
- * associated call_rcu thread. The caller must have previously
- * removed the call_rcu_data structure from per-thread or per-CPU
- * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU
- * call_rcu_data structures or set_thread_call_rcu_data(NULL) for
- * per-thread call_rcu_data structures.
- *
- * We silently refuse to free up the default call_rcu_data structure
- * because that is where we put any leftover callbacks. Note that
- * the possibility of self-spawning callbacks makes it impossible
- * to execute all the callbacks in finite time without putting any
- * newly spawned callbacks somewhere else. The "somewhere else" of
- * last resort is the default call_rcu_data structure.
- *
- * We also silently refuse to free NULL pointers. This simplifies
- * the calling code.
- *
- * The caller must wait for a grace-period to pass between return from
- * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
- * previous call rcu data as argument.
- *
- * Note: introducing __cds_wfcq_splice_blocking() in this function fixed
- * a list corruption bug in the 0.7.x series. The equivalent fix
- * appeared in 0.6.8 for the stable-0.6 branch.
- */
-void call_rcu_data_free(struct call_rcu_data *crdp)
-{
- if (crdp == NULL || crdp == default_call_rcu_data) {
- return;
- }
- if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) {
- uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP);
- wake_call_rcu_thread(crdp);
- while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0)
- (void) poll(NULL, 0, 1);
- }
- if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) {
- /* Create default call rcu data if need be */
- (void) get_default_call_rcu_data();
- __cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head,
- &default_call_rcu_data->cbs_tail,
- &crdp->cbs_head, &crdp->cbs_tail);
- uatomic_add(&default_call_rcu_data->qlen,
- uatomic_read(&crdp->qlen));
- wake_call_rcu_thread(default_call_rcu_data);
- }
-
- call_rcu_lock(&call_rcu_mutex);
- cds_list_del(&crdp->list);
- call_rcu_unlock(&call_rcu_mutex);
-
- free(crdp);
-}
-
-/*
- * Clean up all the per-CPU call_rcu threads.
- */
-void free_all_cpu_call_rcu_data(void)
-{
- int cpu;
- struct call_rcu_data **crdp;
- static int warned = 0;
-
- if (maxcpus <= 0)
- return;
-
- crdp = malloc(sizeof(*crdp) * maxcpus);
- if (!crdp) {
- if (!warned) {
- fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n");
- }
- warned = 1;
- return;
- }
-
- for (cpu = 0; cpu < maxcpus; cpu++) {
- crdp[cpu] = get_cpu_call_rcu_data(cpu);
- if (crdp[cpu] == NULL)
- continue;
- set_cpu_call_rcu_data(cpu, NULL);
- }
- /*
- * Wait for call_rcu sites acting as RCU readers of the
- * call_rcu_data to become quiescent.
- */
- synchronize_rcu();
- for (cpu = 0; cpu < maxcpus; cpu++) {
- if (crdp[cpu] == NULL)
- continue;
- call_rcu_data_free(crdp[cpu]);
- }
- free(crdp);
-}
-
-static
-void free_completion(struct urcu_ref *ref)
-{
- struct call_rcu_completion *completion;
-
- completion = caa_container_of(ref, struct call_rcu_completion, ref);
- free(completion);
-}
-
-static
-void _rcu_barrier_complete(struct rcu_head *head)
-{
- struct call_rcu_completion_work *work;
- struct call_rcu_completion *completion;
-
- work = caa_container_of(head, struct call_rcu_completion_work, head);
- completion = work->completion;
- if (!uatomic_sub_return(&completion->barrier_count, 1))
- call_rcu_completion_wake_up(completion);
- urcu_ref_put(&completion->ref, free_completion);
- free(work);
-}
-
-/*
- * Wait for all in-flight call_rcu callbacks to complete execution.
- */
-void rcu_barrier(void)
-{
- struct call_rcu_data *crdp;
- struct call_rcu_completion *completion;
- int count = 0;
- int was_online;
-
- /* Put in offline state in QSBR. */
- was_online = _rcu_read_ongoing();
- if (was_online)
- rcu_thread_offline();
- /*
- * Calling a rcu_barrier() within a RCU read-side critical
- * section is an error.
- */
- if (_rcu_read_ongoing()) {
- static int warned = 0;
-
- if (!warned) {
- fprintf(stderr, "[error] liburcu: rcu_barrier() called from within RCU read-side critical section.\n");
- }
- warned = 1;
- goto online;
- }
-
- completion = calloc(sizeof(*completion), 1);
- if (!completion)
- urcu_die(errno);
-
- call_rcu_lock(&call_rcu_mutex);
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
- count++;
-
- /* Referenced by rcu_barrier() and each call_rcu thread. */
- urcu_ref_set(&completion->ref, count + 1);
- completion->barrier_count = count;
-
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
- struct call_rcu_completion_work *work;
-
- work = calloc(sizeof(*work), 1);
- if (!work)
- urcu_die(errno);
- work->completion = completion;
- _call_rcu(&work->head, _rcu_barrier_complete, crdp);
- }
- call_rcu_unlock(&call_rcu_mutex);
-
- /* Wait for them */
- for (;;) {
- uatomic_dec(&completion->futex);
- /* Decrement futex before reading barrier_count */
- cmm_smp_mb();
- if (!uatomic_read(&completion->barrier_count))
- break;
- call_rcu_completion_wait(completion);
- }
-
- urcu_ref_put(&completion->ref, free_completion);
-
-online:
- if (was_online)
- rcu_thread_online();
-}
-
-/*
- * Acquire the call_rcu_mutex in order to ensure that the child sees
- * all of the call_rcu() data structures in a consistent state. Ensure
- * that all call_rcu threads are in a quiescent state across fork.
- * Suitable for pthread_atfork() and friends.
- */
-void call_rcu_before_fork(void)
-{
- struct call_rcu_data *crdp;
-
- call_rcu_lock(&call_rcu_mutex);
-
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
- uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSE);
- cmm_smp_mb__after_uatomic_or();
- wake_call_rcu_thread(crdp);
- }
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
- while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) == 0)
- (void) poll(NULL, 0, 1);
- }
-}
-
-/*
- * Clean up call_rcu data structures in the parent of a successful fork()
- * that is not followed by exec() in the child. Suitable for
- * pthread_atfork() and friends.
- */
-void call_rcu_after_fork_parent(void)
-{
- struct call_rcu_data *crdp;
-
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
- uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE);
- cds_list_for_each_entry(crdp, &call_rcu_data_list, list) {
- while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0)
- (void) poll(NULL, 0, 1);
- }
- call_rcu_unlock(&call_rcu_mutex);
-}
-
-/*
- * Clean up call_rcu data structures in the child of a successful fork()
- * that is not followed by exec(). Suitable for pthread_atfork() and
- * friends.
- */
-void call_rcu_after_fork_child(void)
-{
- struct call_rcu_data *crdp, *next;
-
- /* Release the mutex. */
- call_rcu_unlock(&call_rcu_mutex);
-
- /* Do nothing when call_rcu() has not been used */
- if (cds_list_empty(&call_rcu_data_list))
- return;
-
- /*
- * Allocate a new default call_rcu_data structure in order
- * to get a working call_rcu thread to go with it.
- */
- default_call_rcu_data = NULL;
- (void)get_default_call_rcu_data();
-
- /* Cleanup call_rcu_data pointers before use */
- maxcpus_reset();
- free(per_cpu_call_rcu_data);
- rcu_set_pointer(&per_cpu_call_rcu_data, NULL);
- URCU_TLS(thread_call_rcu_data) = NULL;
-
- /*
- * Dispose of all of the rest of the call_rcu_data structures.
- * Leftover call_rcu callbacks will be merged into the new
- * default call_rcu thread queue.
- */
- cds_list_for_each_entry_safe(crdp, next, &call_rcu_data_list, list) {
- if (crdp == default_call_rcu_data)
- continue;
- uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED);
- call_rcu_data_free(crdp);
- }
-}
projects / userspace-rcu.git / blobdiff