#include <pthread.h>
#include <assert.h>
#include <limits.h>
+#include <syscall.h>
+#include <unistd.h>
#include <compiler.h>
#include <arch.h>
(_________p1); \
})
+#define futex(...) syscall(__NR_futex, __VA_ARGS__)
+#define FUTEX_WAIT 0
+#define FUTEX_WAKE 1
+
/*
* This code section can only be included in LGPL 2.1 compatible source code.
* See below for the function call wrappers which can be used in code meant to
*/
#define KICK_READER_LOOPS 10000
+/*
+ * Active attempts to check for reader Q.S. before calling futex().
+ */
+#define RCU_QS_ACTIVE_ATTEMPTS 100
+
#ifdef DEBUG_RCU
#define rcu_assert(args...) assert(args)
#else
extern unsigned long __thread rcu_reader_qs_gp;
+extern int gp_futex;
+
+/*
+ * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
+ */
+static inline void wake_up_gp(void)
+{
+ if (unlikely(atomic_read(&gp_futex) == -1)) {
+ atomic_set(&gp_futex, 0);
+ futex(&gp_futex, FUTEX_WAKE, 1,
+ NULL, NULL, 0);
+ }
+}
+
#if (BITS_PER_LONG < 64)
static inline int rcu_gp_ongoing(unsigned long *value)
{
{
smp_mb();
_STORE_SHARED(rcu_reader_qs_gp, _LOAD_SHARED(urcu_gp_ctr));
+ smp_mb(); /* write rcu_reader_qs_gp before read futex */
+ wake_up_gp();
smp_mb();
}
{
smp_mb();
STORE_SHARED(rcu_reader_qs_gp, 0);
+ smp_mb(); /* write rcu_reader_qs_gp before read futex */
+ wake_up_gp();
}
static inline void _rcu_thread_online(void)