#define _BSD_SOURCE
#define _GNU_SOURCE
#define _LGPL_SOURCE
+#define _DEFAULT_SOURCE
#include <stdio.h>
#include <pthread.h>
#include <signal.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
/*
* 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 a few loops waiting for it.
+ * per-se), kick it after 10 loops waiting for it.
*/
-#define KICK_READER_LOOPS 10000
+#define KICK_READER_LOOPS 10
/*
* Active attempts to check for reader Q.S. before calling futex().
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;
int32_t 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 CDS_LIST_HEAD(registry);
#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 (CMM_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();
- _CMM_STORE_SHARED(rcu_reader.need_mb, 0);
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader).need_mb, 0);
cmm_smp_mb();
}
poll(NULL,0,10);
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();
/*
* synchronize_rcu() waiting. Single thread.
+ * Always called with rcu_registry lock held. Releases this lock and
+ * grabs it again. Holds the lock when it returns.
*/
static void wait_gp(void)
{
- /* Read reader_gp before read futex */
+ /*
+ * Read reader_gp before read futex. smp_mb_master() needs to
+ * be called with the rcu registry lock held in RCU_SIGNAL
+ * flavor.
+ */
smp_mb_master(RCU_MB_GROUP);
- if (uatomic_read(&gp_futex) == -1)
- futex_async(&gp_futex, FUTEX_WAIT, -1,
- NULL, NULL, 0);
+ /* Temporarily unlock the registry lock. */
+ mutex_unlock(&rcu_registry_lock);
+ if (uatomic_read(&gp_futex) != -1)
+ goto end;
+ while (futex_async(&gp_futex, FUTEX_WAIT, -1,
+ NULL, NULL, 0)) {
+ switch (errno) {
+ case EWOULDBLOCK:
+ /* Value already changed. */
+ goto end;
+ case EINTR:
+ /* Retry if interrupted by signal. */
+ break; /* Get out of switch. */
+ default:
+ /* Unexpected error. */
+ urcu_die(errno);
+ }
+ }
+end:
+ /*
+ * Re-lock the registry lock before the next loop.
+ */
+ mutex_lock(&rcu_registry_lock);
}
+/*
+ * 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)
{
CDS_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 */
/* Switch parity: 0 -> 1, 1 -> 0 */
CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE);
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);
#ifndef HAS_INCOHERENT_CACHES
if (cds_list_empty(®istry)) {
- if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+ 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)
+ if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+ /* wait_gp unlocks/locks registry lock. */
wait_gp();
- else
+ } else {
+ /* Temporarily unlock the registry lock. */
+ mutex_unlock(&rcu_registry_lock);
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 (cds_list_empty(®istry)) {
- if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+ 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:
+ wait_gp_loops = 0;
+ }
+ if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+ /* wait_gp unlocks/locks registry lock. */
+ wait_gp();
+ wait_gp_loops++;
+ } else {
+ /* Temporarily unlock the registry lock. */
+ mutex_unlock(&rcu_registry_lock);
caa_cpu_relax();
+ /*
+ * Re-lock the registry lock before the
+ * next loop.
+ */
+ mutex_lock(&rcu_registry_lock);
}
}
#endif /* #else #ifndef HAS_INCOHERENT_CACHES */
void synchronize_rcu(void)
{
mutex_lock(&rcu_gp_lock);
+ mutex_lock(&rcu_registry_lock);
if (cds_list_empty(®istry))
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 */
* 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();
/*
* 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);
}
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 */
- cds_list_add(&rcu_reader.node, ®istry);
- mutex_unlock(&rcu_gp_lock);
+ cds_list_add(&URCU_TLS(rcu_reader).node, ®istry);
+ mutex_unlock(&rcu_registry_lock);
}
void rcu_unregister_thread(void)
{
- mutex_lock(&rcu_gp_lock);
- cds_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
* executed on.
*/
cmm_smp_mb();
- _CMM_STORE_SHARED(rcu_reader.need_mb, 0);
+ _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 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)
{
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)
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(cds_list_empty(®istry));
}
#endif /* #ifdef RCU_SIGNAL */
+DEFINE_RCU_FLAVOR(rcu_flavor);
+
#include "urcu-call-rcu-impl.h"
#include "urcu-defer-impl.h"
projects / userspace-rcu.git / blobdiff