#include <errno.h>
#include <poll.h>
+#include "urcu/arch.h"
#include "urcu/wfcqueue.h"
#include "urcu/map/urcu.h"
#include "urcu/static/urcu.h"
*/
#define RCU_QS_ACTIVE_ATTEMPTS 100
-/*
- * RCU_MEMBARRIER is only possibly available on Linux.
- */
-#if defined(RCU_MEMBARRIER) && defined(__linux__)
-#include <urcu/syscall-compat.h>
-#endif
-
-/* If the headers do not support SYS_membarrier, fall back on RCU_MB */
-#ifdef SYS_membarrier
-# define membarrier(...) syscall(SYS_membarrier, __VA_ARGS__)
+/* 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
-#define MEMBARRIER_EXPEDITED (1 << 0)
-#define MEMBARRIER_DELAYED (1 << 1)
-#define MEMBARRIER_QUERY (1 << 16)
+enum membarrier_cmd {
+ MEMBARRIER_CMD_QUERY = 0,
+ MEMBARRIER_CMD_SHARED = (1 << 0),
+};
#ifdef RCU_MEMBARRIER
static int init_done;
}
#ifdef RCU_MEMBARRIER
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
{
if (caa_likely(rcu_has_sys_membarrier))
- (void) membarrier(MEMBARRIER_EXPEDITED);
+ (void) membarrier(MEMBARRIER_CMD_SHARED, 0);
else
cmm_smp_mb();
}
#endif
#ifdef RCU_MB
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
{
cmm_smp_mb();
}
cmm_smp_mb(); /* read ->need_mb before ending the barrier */
}
-static void smp_mb_master(int group)
+static void smp_mb_master(void)
{
force_mb_all_readers();
}
/*
* 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 */
- smp_mb_master(RCU_MB_GROUP);
- if (uatomic_read(&rcu_gp.futex) == -1)
- futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
- NULL, NULL, 0);
+ /*
+ * 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();
+ /* Temporarily unlock the registry lock. */
+ mutex_unlock(&rcu_registry_lock);
+ if (uatomic_read(&rcu_gp.futex) != -1)
+ goto end;
+ while (futex_async(&rcu_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);
}
/*
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
uatomic_dec(&rcu_gp.futex);
/* Write futex before read reader_gp */
- smp_mb_master(RCU_MB_GROUP);
+ smp_mb_master();
}
cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
if (cds_list_empty(input_readers)) {
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
- smp_mb_master(RCU_MB_GROUP);
+ smp_mb_master();
uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
- /* Temporarily unlock the registry lock. */
- mutex_unlock(&rcu_registry_lock);
- 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);
+ /*
+ * Re-lock the registry lock before the
+ * next loop.
+ */
+ mutex_lock(&rcu_registry_lock);
+ }
}
#else /* #ifndef HAS_INCOHERENT_CACHES */
/*
if (cds_list_empty(input_readers)) {
if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
/* Read reader_gp before write futex */
- smp_mb_master(RCU_MB_GROUP);
+ smp_mb_master();
uatomic_set(&rcu_gp.futex, 0);
}
break;
} else {
if (wait_gp_loops == KICK_READER_LOOPS) {
- smp_mb_master(RCU_MB_GROUP);
+ 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 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);
}
- /* Re-lock the registry lock before the next loop. */
- mutex_lock(&rcu_registry_lock);
}
#endif /* #else #ifndef HAS_INCOHERENT_CACHES */
}
* because it iterates on reader threads.
*/
/* Write new ptr before changing the qparity */
- smp_mb_master(RCU_MB_GROUP);
+ smp_mb_master();
/*
* Wait for readers to observe original parity or be quiescent.
* being freed. Must be done within rcu_registry_lock because it
* iterates on reader threads.
*/
- smp_mb_master(RCU_MB_GROUP);
+ smp_mb_master();
out:
mutex_unlock(&rcu_registry_lock);
mutex_unlock(&rcu_gp_lock);
assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK));
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 */
cds_list_add(&URCU_TLS(rcu_reader).node, ®istry);
mutex_unlock(&rcu_registry_lock);
void rcu_unregister_thread(void)
{
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(MEMBARRIER_EXPEDITED | MEMBARRIER_QUERY))
+ ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
+ if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
rcu_has_sys_membarrier = 1;
+ }
}
#endif
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