X-Git-Url: http://git.liburcu.org/?p=userspace-rcu.git;a=blobdiff_plain;f=urcu.c;h=c5abeafa06d3bd796a2148a1effdf90c2c959dd1;hp=9c556aa6bd9d3eeff75ce2c8b857bfb59ca4596b;hb=7a3e2ed26a6be1deac2cfde1d062526497d4ae9f;hpb=5481ddb381061bda64aebc039900d21cac6a6caf

diff --git a/urcu.c b/urcu.c
index 9c556aa..c5abeaf 100644
--- a/urcu.c
+++ b/urcu.c
@@ -24,18 +24,43 @@
  */
 
 #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/wfqueue.h"
+#include "urcu/map/urcu.h"
+#include "urcu/static/urcu.h"
+#include "urcu-pointer.h"
+#include "urcu/tls-compat.h"
+
+#include "urcu-die.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
 
 #ifdef RCU_MEMBARRIER
 static int init_done;
@@ -57,9 +82,23 @@ void __attribute__((constructor)) rcu_init(void);
 void __attribute__((destructor)) rcu_exit(void);
 #endif
 
+/*
+ * rcu_gp_lock ensures mutual exclusion between threads calling
+ * synchronize_rcu().
+ */
 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;
 
-int gp_futex;
+int32_t gp_futex;
 
 /*
  * Global grace period counter.
@@ -68,19 +107,18 @@ int gp_futex;
  * Written to only by writer with mutex taken. Read by both writer and readers.
  */
 unsigned long 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_GLOBAL(struct rcu_reader, rcu_reader);
 
 #ifdef DEBUG_YIELD
 unsigned int yield_active;
-unsigned int __thread rand_yield;
+__DEFINE_URCU_TLS_GLOBAL(unsigned int, rand_yield);
 #endif
 
-static LIST_HEAD(registry);
+static CDS_LIST_HEAD(registry);
 
 static void mutex_lock(pthread_mutex_t *mutex)
 {
@@ -88,20 +126,15 @@ static void mutex_lock(pthread_mutex_t *mutex)
 
 #ifndef DISTRUST_SIGNALS_EXTREME
 	ret = pthread_mutex_lock(mutex);
-	if (ret) {
-		perror("Error in pthread mutex lock");
-		exit(-1);
-	}
+	if (ret)
+		urcu_die(ret);
 #else /* #ifndef DISTRUST_SIGNALS_EXTREME */
 	while ((ret = pthread_mutex_trylock(mutex)) != 0) {
-		if (ret != EBUSY && ret != EINTR) {
-			printf("ret = %d, errno = %d\n", ret, errno);
-			perror("Error in pthread mutex lock");
-			exit(-1);
-		}
-		if (LOAD_SHARED(rcu_reader.need_mb)) {
+		if (ret != EBUSY && ret != EINTR)
+			urcu_die(ret);
+		if (CMM_LOAD_SHARED(URCU_TLS(rcu_reader).need_mb)) {
 			cmm_smp_mb();
-			_STORE_SHARED(rcu_reader.need_mb, 0);
+			_CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
 			cmm_smp_mb();
 		}
 		poll(NULL,0,10);
@@ -114,16 +147,14 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 	int ret;
 
 	ret = pthread_mutex_unlock(mutex);
-	if (ret) {
-		perror("Error in pthread mutex unlock");
-		exit(-1);
-	}
+	if (ret)
+		urcu_die(ret);
 }
 
 #ifdef RCU_MEMBARRIER
 static void smp_mb_master(int group)
 {
-	if (likely(has_sys_membarrier))
+	if (caa_likely(has_sys_membarrier))
 		membarrier(MEMBARRIER_EXPEDITED);
 	else
 		cmm_smp_mb();
@@ -146,7 +177,7 @@ static void force_mb_all_readers(void)
 	 * 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 cmm_smp_mb(). But beware, we assume it performs
@@ -154,8 +185,8 @@ static void force_mb_all_readers(void)
 	 * 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, node) {
-		STORE_SHARED(index->need_mb, 1);
+	cds_list_for_each_entry(index, &registry, node) {
+		CMM_STORE_SHARED(index->need_mb, 1);
 		pthread_kill(index->tid, SIGRCU);
 	}
 	/*
@@ -171,8 +202,8 @@ 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, node) {
-		while (LOAD_SHARED(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);
 		}
@@ -193,19 +224,39 @@ static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
 	smp_mb_master(RCU_MB_GROUP);
-	if (uatomic_read(&gp_futex) == -1)
-		futex_async(&gp_futex, FUTEX_WAIT, -1,
-		      NULL, NULL, 0);
+	if (uatomic_read(&gp_futex) != -1)
+		return;
+	while (futex_async(&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);
+		}
+	}
 }
 
+/*
+ * Always called with rcu_registry lock held. Releases this lock between
+ * iterations and grabs it again. Holds the lock when it returns.
+ */
 void update_counter_and_wait(void)
 {
-	LIST_HEAD(qsreaders);
-	int wait_loops = 0;
+	CDS_LIST_HEAD(qsreaders);
+	unsigned int wait_loops = 0;
 	struct rcu_reader *index, *tmp;
+#ifdef HAS_INCOHERENT_CACHES
+	unsigned int wait_gp_loops = 0;
+#endif /* HAS_INCOHERENT_CACHES */
 
 	/* Switch parity: 0 -> 1, 1 -> 0 */
-	STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
+	CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
 
 	/*
 	 * Must commit rcu_gp_ctr update to memory before waiting for quiescent
@@ -224,81 +275,95 @@ void update_counter_and_wait(void)
 	cmm_smp_mb();
 
 	/*
-	 * Wait for each thread rcu_reader.ctr count to become 0.
+	 * Wait for each thread URCU_TLS(rcu_reader).ctr count to become 0.
 	 */
 	for (;;) {
-		wait_loops++;
-		if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+		if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
+			wait_loops++;
+		if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 			uatomic_dec(&gp_futex);
 			/* Write futex before read reader_gp */
 			smp_mb_master(RCU_MB_GROUP);
 		}
 
-		list_for_each_entry_safe(index, tmp, &registry, node) {
+		cds_list_for_each_entry_safe(index, tmp, &registry, node) {
 			if (!rcu_gp_ongoing(&index->ctr))
-				list_move(&index->node, &qsreaders);
+				cds_list_move(&index->node, &qsreaders);
 		}
 
 #ifndef HAS_INCOHERENT_CACHES
-		if (list_empty(&registry)) {
-			if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+		if (cds_list_empty(&registry)) {
+			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
 				smp_mb_master(RCU_MB_GROUP);
 				uatomic_set(&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(&registry)) {
+			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
 				/* Read reader_gp before write futex */
 				smp_mb_master(RCU_MB_GROUP);
 				uatomic_set(&gp_futex, 0);
 			}
 			break;
 		} else {
-			switch (wait_loops) {
-			case RCU_QS_ACTIVE_ATTEMPTS:
-				wait_gp();
-				break; /* only escape switch */
-			case KICK_READER_LOOPS:
+			if (wait_gp_loops == KICK_READER_LOOPS) {
 				smp_mb_master(RCU_MB_GROUP);
-				wait_loops = 0;
-				break; /* only escape switch */
-			default:
-				cpu_relax();
+				wait_gp_loops = 0;
+			}
+			/* Temporarily unlock the registry lock. */
+			mutex_unlock(&rcu_registry_lock);
+			if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+				wait_gp();
+				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);
+	cds_list_splice(&qsreaders, &registry);
 }
 
 void synchronize_rcu(void)
 {
 	mutex_lock(&rcu_gp_lock);
+	mutex_lock(&rcu_registry_lock);
 
-	if (list_empty(&registry))
+	if (cds_list_empty(&registry))
 		goto out;
 
-	/* All threads should read qparity before accessing data structure
-	 * where new ptr points to. Must be done within rcu_gp_lock because it
-	 * iterates on reader threads.*/
+	/*
+	 * 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.
+	 */
 	/* Write new ptr before changing the qparity */
 	smp_mb_master(RCU_MB_GROUP);
 
 	/*
 	 * Wait for previous parity to be empty of readers.
+	 * update_counter_and_wait() can release and grab again
+	 * rcu_registry_lock interally.
 	 */
 	update_counter_and_wait();	/* 0 -> 1, wait readers in parity 0 */
 
@@ -307,7 +372,7 @@ void synchronize_rcu(void)
 	 * 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
-	 * rcu_reader ctr before store to rcu_gp_ctr.
+	 * URCU_TLS(rcu_reader).ctr before store to rcu_gp_ctr.
 	 */
 	cmm_barrier();
 
@@ -320,14 +385,19 @@ void synchronize_rcu(void)
 
 	/*
 	 * Wait for previous parity to be empty of readers.
+	 * update_counter_and_wait() can release and grab again
+	 * rcu_registry_lock interally.
 	 */
 	update_counter_and_wait();	/* 1 -> 0, wait readers in parity 1 */
 
-	/* Finish waiting for reader threads before letting the old ptr being
-	 * freed. Must be done within rcu_gp_lock because it iterates on reader
-	 * threads. */
+	/*
+	 * 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(RCU_MB_GROUP);
 out:
+	mutex_unlock(&rcu_registry_lock);
 	mutex_unlock(&rcu_gp_lock);
 }
 
@@ -347,21 +417,21 @@ void rcu_read_unlock(void)
 
 void rcu_register_thread(void)
 {
-	rcu_reader.tid = pthread_self();
-	assert(rcu_reader.need_mb == 0);
-	assert(!(rcu_reader.ctr & RCU_GP_CTR_NEST_MASK));
+	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));
 
-	mutex_lock(&rcu_gp_lock);
+	mutex_lock(&rcu_registry_lock);
 	rcu_init();	/* In case gcc does not support constructor attribute */
-	list_add(&rcu_reader.node, &registry);
-	mutex_unlock(&rcu_gp_lock);
+	cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
+	mutex_unlock(&rcu_registry_lock);
 }
 
 void rcu_unregister_thread(void)
 {
-	mutex_lock(&rcu_gp_lock);
-	list_del(&rcu_reader.node);
-	mutex_unlock(&rcu_gp_lock);
+	mutex_lock(&rcu_registry_lock);
+	cds_list_del(&URCU_TLS(rcu_reader).node);
+	mutex_unlock(&rcu_registry_lock);
 }
 
 #ifdef RCU_MEMBARRIER
@@ -384,7 +454,7 @@ static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
 	 * executed on.
 	 */
 	cmm_smp_mb();
-	_STORE_SHARED(rcu_reader.need_mb, 0);
+	_CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
 	cmm_smp_mb();
 }
 
@@ -392,9 +462,9 @@ static void sigrcu_handler(int signo, siginfo_t *siginfo, void *context)
  * 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 rcu_gp_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)
 {
@@ -409,10 +479,8 @@ 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)
@@ -421,11 +489,15 @@ void rcu_exit(void)
 	int ret;
 
 	ret = sigaction(SIGRCU, NULL, &act);
-	if (ret) {
-		perror("Error in sigaction");
-		exit(-1);
-	}
+	if (ret)
+		urcu_die(errno);
 	assert(act.sa_sigaction == sigrcu_handler);
-	assert(list_empty(&registry));
+	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"