X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=src%2Furcu-call-rcu-impl.h;h=9f85d55b403c5fa1f882947af021c6cae460d712;hb=ed4c6ca597ff4211e1379a650403836fd59e9368;hp=bfa53f8e09f920a833559ba7b334a04bf3cfcf47;hpb=6893800a4d1cc14dff0395ddcd660a5138db183d;p=userspace-rcu.git

diff --git a/src/urcu-call-rcu-impl.h b/src/urcu-call-rcu-impl.h
index bfa53f8..9f85d55 100644
--- a/src/urcu-call-rcu-impl.h
+++ b/src/urcu-call-rcu-impl.h
@@ -24,7 +24,6 @@
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
@@ -35,14 +34,17 @@
 #include <sched.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/assert.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"
+#include "urcu-utils.h"
+#include "compat-smp.h"
 
 #define SET_AFFINITY_CHECK_PERIOD		(1U << 8)	/* 256 */
 #define SET_AFFINITY_CHECK_PERIOD_MASK		(SET_AFFINITY_CHECK_PERIOD - 1)
@@ -99,6 +101,9 @@ static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 static struct call_rcu_data *default_call_rcu_data;
 
+static struct urcu_atfork *registered_rculfhash_atfork;
+static unsigned long registered_rculfhash_atfork_refcount;
+
 /*
  * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
  * available, then we can have call_rcu threads assigned to individual
@@ -116,11 +121,11 @@ static struct call_rcu_data *default_call_rcu_data;
  */
 
 static struct call_rcu_data **per_cpu_call_rcu_data;
-static long maxcpus;
+static long cpus_array_len;
 
-static void maxcpus_reset(void)
+static void cpus_array_len_reset(void)
 {
-	maxcpus = 0;
+	cpus_array_len = 0;
 }
 
 /* Allocate the array if it has not already been allocated. */
@@ -130,15 +135,15 @@ static void alloc_cpu_call_rcu_data(void)
 	struct call_rcu_data **p;
 	static int warned = 0;
 
-	if (maxcpus != 0)
+	if (cpus_array_len != 0)
 		return;
-	maxcpus = sysconf(_SC_NPROCESSORS_CONF);
-	if (maxcpus <= 0) {
+	cpus_array_len = get_possible_cpus_array_len();
+	if (cpus_array_len <= 0) {
 		return;
 	}
-	p = malloc(maxcpus * sizeof(*per_cpu_call_rcu_data));
+	p = malloc(cpus_array_len * sizeof(*per_cpu_call_rcu_data));
 	if (p != NULL) {
-		memset(p, '\0', maxcpus * sizeof(*per_cpu_call_rcu_data));
+		memset(p, '\0', cpus_array_len * sizeof(*per_cpu_call_rcu_data));
 		rcu_set_pointer(&per_cpu_call_rcu_data, p);
 	} else {
 		if (!warned) {
@@ -156,9 +161,9 @@ static void alloc_cpu_call_rcu_data(void)
  * constant.
  */
 static struct call_rcu_data **per_cpu_call_rcu_data = NULL;
-static const long maxcpus = -1;
+static const long cpus_array_len = -1;
 
-static void maxcpus_reset(void)
+static void cpus_array_len_reset(void)
 {
 }
 
@@ -195,7 +200,7 @@ static void call_rcu_unlock(pthread_mutex_t *pmp)
  * Losing affinity can be caused by CPU hotunplug/hotplug, or by
  * cpuset(7).
  */
-#if HAVE_SCHED_SETAFFINITY
+#ifdef HAVE_SCHED_SETAFFINITY
 static
 int set_thread_cpu_affinity(struct call_rcu_data *crdp)
 {
@@ -211,11 +216,8 @@ int set_thread_cpu_affinity(struct call_rcu_data *crdp)
 
 	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
@@ -229,7 +231,7 @@ int set_thread_cpu_affinity(struct call_rcu_data *crdp)
 }
 #else
 static
-int set_thread_cpu_affinity(struct call_rcu_data *crdp)
+int set_thread_cpu_affinity(struct call_rcu_data *crdp __attribute__((unused)))
 {
 	return 0;
 }
@@ -239,17 +241,25 @@ 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)) {
+	while (uatomic_read(&crdp->futex) == -1) {
+		if (!futex_async(&crdp->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+			/*
+			 * Prior queued wakeups queued by unrelated code
+			 * using the same address can cause futex wait to
+			 * return 0 even through the futex value is still
+			 * -1 (spurious wakeups). Check the value again
+			 * in user-space to validate whether it really
+			 * differs from -1.
+			 */
+			continue;
+		}
 		switch (errno) {
-		case EWOULDBLOCK:
+		case EAGAIN:
 			/* Value already changed. */
 			return;
 		case EINTR:
 			/* Retry if interrupted by signal. */
-			break;	/* Get out of switch. */
+			break;	/* Get out of switch. Check again. */
 		default:
 			/* Unexpected error. */
 			urcu_die(errno);
@@ -273,17 +283,25 @@ 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)) {
+	while (uatomic_read(&completion->futex) == -1) {
+		if (!futex_async(&completion->futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+			/*
+			 * Prior queued wakeups queued by unrelated code
+			 * using the same address can cause futex wait to
+			 * return 0 even through the futex value is still
+			 * -1 (spurious wakeups). Check the value again
+			 * in user-space to validate whether it really
+			 * differs from -1.
+			 */
+			continue;
+		}
 		switch (errno) {
-		case EWOULDBLOCK:
+		case EAGAIN:
 			/* Value already changed. */
 			return;
 		case EINTR:
 			/* Retry if interrupted by signal. */
-			break;	/* Get out of switch. */
+			break;	/* Get out of switch. Check again. */
 		default:
 			/* Unexpected error. */
 			urcu_die(errno);
@@ -354,8 +372,8 @@ static void *call_rcu_thread(void *arg)
 		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);
+		urcu_posix_assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
+		urcu_posix_assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
 		if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) {
 			synchronize_rcu();
 			cbcount = 0;
@@ -416,6 +434,7 @@ static void call_rcu_data_init(struct call_rcu_data **crdpp,
 {
 	struct call_rcu_data *crdp;
 	int ret;
+	sigset_t newmask, oldmask;
 
 	crdp = malloc(sizeof(*crdp));
 	if (crdp == NULL)
@@ -430,9 +449,18 @@ static void call_rcu_data_init(struct call_rcu_data **crdpp,
 	crdp->gp_count = 0;
 	cmm_smp_mb();  /* Structure initialized before pointer is planted. */
 	*crdpp = crdp;
+
+	ret = sigfillset(&newmask);
+	urcu_posix_assert(!ret);
+	ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
+	urcu_posix_assert(!ret);
+
 	ret = pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp);
 	if (ret)
 		urcu_die(ret);
+
+	ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
+	urcu_posix_assert(!ret);
 }
 
 /*
@@ -453,11 +481,11 @@ struct call_rcu_data *get_cpu_call_rcu_data(int cpu)
 	pcpu_crdp = rcu_dereference(per_cpu_call_rcu_data);
 	if (pcpu_crdp == NULL)
 		return NULL;
-	if (!warned && maxcpus > 0 && (cpu < 0 || maxcpus <= cpu)) {
+	if (!warned && cpus_array_len > 0 && (cpu < 0 || cpus_array_len <= cpu)) {
 		fprintf(stderr, "[error] liburcu: get CPU # out of range\n");
 		warned = 1;
 	}
-	if (cpu < 0 || maxcpus <= cpu)
+	if (cpu < 0 || cpus_array_len <= cpu)
 		return NULL;
 	return rcu_dereference(pcpu_crdp[cpu]);
 }
@@ -515,7 +543,7 @@ int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp)
 
 	call_rcu_lock(&call_rcu_mutex);
 	alloc_cpu_call_rcu_data();
-	if (cpu < 0 || maxcpus <= cpu) {
+	if (cpu < 0 || cpus_array_len <= cpu) {
 		if (!warned) {
 			fprintf(stderr, "[error] liburcu: set CPU # out of range\n");
 			warned = 1;
@@ -580,7 +608,7 @@ struct call_rcu_data *get_call_rcu_data(void)
 	if (URCU_TLS(thread_call_rcu_data) != NULL)
 		return URCU_TLS(thread_call_rcu_data);
 
-	if (maxcpus > 0) {
+	if (cpus_array_len > 0) {
 		crd = get_cpu_call_rcu_data(urcu_sched_getcpu());
 		if (crd)
 			return crd;
@@ -631,7 +659,7 @@ int create_all_cpu_call_rcu_data(unsigned long flags)
 	call_rcu_lock(&call_rcu_mutex);
 	alloc_cpu_call_rcu_data();
 	call_rcu_unlock(&call_rcu_mutex);
-	if (maxcpus <= 0) {
+	if (cpus_array_len <= 0) {
 		errno = EINVAL;
 		return -EINVAL;
 	}
@@ -639,7 +667,7 @@ int create_all_cpu_call_rcu_data(unsigned long flags)
 		errno = ENOMEM;
 		return -ENOMEM;
 	}
-	for (i = 0; i < maxcpus; i++) {
+	for (i = 0; i < cpus_array_len; i++) {
 		call_rcu_lock(&call_rcu_mutex);
 		if (get_cpu_call_rcu_data(i)) {
 			call_rcu_unlock(&call_rcu_mutex);
@@ -749,9 +777,13 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
 		while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0)
 			(void) poll(NULL, 0, 1);
 	}
+	call_rcu_lock(&call_rcu_mutex);
 	if (!cds_wfcq_empty(&crdp->cbs_head, &crdp->cbs_tail)) {
-		/* Create default call rcu data if need be */
+		call_rcu_unlock(&call_rcu_mutex);
+		/* Create default call rcu data if need be. */
+		/* CBs queued here will be handed to the default list. */
 		(void) get_default_call_rcu_data();
+		call_rcu_lock(&call_rcu_mutex);
 		__cds_wfcq_splice_blocking(&default_call_rcu_data->cbs_head,
 			&default_call_rcu_data->cbs_tail,
 			&crdp->cbs_head, &crdp->cbs_tail);
@@ -760,7 +792,6 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
 		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);
 
@@ -776,10 +807,10 @@ void free_all_cpu_call_rcu_data(void)
 	struct call_rcu_data **crdp;
 	static int warned = 0;
 
-	if (maxcpus <= 0)
+	if (cpus_array_len <= 0)
 		return;
 
-	crdp = malloc(sizeof(*crdp) * maxcpus);
+	crdp = malloc(sizeof(*crdp) * cpus_array_len);
 	if (!crdp) {
 		if (!warned) {
 			fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n");
@@ -788,7 +819,7 @@ void free_all_cpu_call_rcu_data(void)
 		return;
 	}
 
-	for (cpu = 0; cpu < maxcpus; cpu++) {
+	for (cpu = 0; cpu < cpus_array_len; cpu++) {
 		crdp[cpu] = get_cpu_call_rcu_data(cpu);
 		if (crdp[cpu] == NULL)
 			continue;
@@ -799,7 +830,7 @@ void free_all_cpu_call_rcu_data(void)
 	 * call_rcu_data to become quiescent.
 	 */
 	synchronize_rcu();
-	for (cpu = 0; cpu < maxcpus; cpu++) {
+	for (cpu = 0; cpu < cpus_array_len; cpu++) {
 		if (crdp[cpu] == NULL)
 			continue;
 		call_rcu_data_free(crdp[cpu]);
@@ -907,9 +938,14 @@ online:
 void call_rcu_before_fork(void)
 {
 	struct call_rcu_data *crdp;
+	struct urcu_atfork *atfork;
 
 	call_rcu_lock(&call_rcu_mutex);
 
+	atfork = registered_rculfhash_atfork;
+	if (atfork)
+		atfork->before_fork(atfork->priv);
+
 	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();
@@ -929,6 +965,7 @@ void call_rcu_before_fork(void)
 void call_rcu_after_fork_parent(void)
 {
 	struct call_rcu_data *crdp;
+	struct urcu_atfork *atfork;
 
 	cds_list_for_each_entry(crdp, &call_rcu_data_list, list)
 		uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE);
@@ -936,6 +973,9 @@ void call_rcu_after_fork_parent(void)
 		while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0)
 			(void) poll(NULL, 0, 1);
 	}
+	atfork = registered_rculfhash_atfork;
+	if (atfork)
+		atfork->after_fork_parent(atfork->priv);
 	call_rcu_unlock(&call_rcu_mutex);
 }
 
@@ -947,10 +987,15 @@ void call_rcu_after_fork_parent(void)
 void call_rcu_after_fork_child(void)
 {
 	struct call_rcu_data *crdp, *next;
+	struct urcu_atfork *atfork;
 
 	/* Release the mutex. */
 	call_rcu_unlock(&call_rcu_mutex);
 
+	atfork = registered_rculfhash_atfork;
+	if (atfork)
+		atfork->after_fork_child(atfork->priv);
+
 	/* Do nothing when call_rcu() has not been used */
 	if (cds_list_empty(&call_rcu_data_list))
 		return;
@@ -963,7 +1008,7 @@ void call_rcu_after_fork_child(void)
 	(void)get_default_call_rcu_data();
 
 	/* Cleanup call_rcu_data pointers before use */
-	maxcpus_reset();
+	cpus_array_len_reset();
 	free(per_cpu_call_rcu_data);
 	rcu_set_pointer(&per_cpu_call_rcu_data, NULL);
 	URCU_TLS(thread_call_rcu_data) = NULL;
@@ -980,3 +1025,23 @@ void call_rcu_after_fork_child(void)
 		call_rcu_data_free(crdp);
 	}
 }
+
+void urcu_register_rculfhash_atfork(struct urcu_atfork *atfork)
+{
+	call_rcu_lock(&call_rcu_mutex);
+	if (registered_rculfhash_atfork_refcount++)
+		goto end;
+	registered_rculfhash_atfork = atfork;
+end:
+	call_rcu_unlock(&call_rcu_mutex);
+}
+
+void urcu_unregister_rculfhash_atfork(struct urcu_atfork *atfork __attribute__((unused)))
+{
+	call_rcu_lock(&call_rcu_mutex);
+	if (--registered_rculfhash_atfork_refcount)
+		goto end;
+	registered_rculfhash_atfork = NULL;
+end:
+	call_rcu_unlock(&call_rcu_mutex);
+}