#include <unistd.h>
#include <sys/mman.h>
+#include "urcu/arch.h"
#include "urcu/wfcqueue.h"
#include "urcu/map/urcu-bp.h"
#include "urcu/static/urcu-bp.h"
static
int rcu_bp_refcount;
+/* If the headers do not support membarrier system call, fall back smp_mb. */
+#ifdef __NR_membarrier
+# define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__)
+#else
+# define membarrier(...) -ENOSYS
+#endif
+
+enum membarrier_cmd {
+ MEMBARRIER_CMD_QUERY = 0,
+ MEMBARRIER_CMD_SHARED = (1 << 0),
+};
+
static
void __attribute__((constructor)) rcu_bp_init(void);
static
void __attribute__((destructor)) rcu_bp_exit(void);
+int urcu_bp_has_sys_membarrier;
+
/*
* rcu_gp_lock ensures mutual exclusion between threads calling
* synchronize_rcu().
urcu_die(ret);
}
+static void smp_mb_master(void)
+{
+ if (caa_likely(urcu_bp_has_sys_membarrier))
+ (void) membarrier(MEMBARRIER_CMD_SHARED, 0);
+ else
+ cmm_smp_mb();
+}
+
/*
* Always called with rcu_registry lock held. Releases this lock between
* iterations and grabs it again. Holds the lock when it returns.
/* All threads should read qparity before accessing data structure
* where new ptr points to. */
/* Write new ptr before changing the qparity */
- cmm_smp_mb();
+ smp_mb_master();
/*
* Wait for readers to observe original parity or be quiescent.
* Finish waiting for reader threads before letting the old ptr being
* freed.
*/
- cmm_smp_mb();
+ smp_mb_master();
out:
mutex_unlock(&rcu_registry_lock);
mutex_unlock(&rcu_gp_lock);
urcu_bp_thread_exit_notifier);
if (ret)
abort();
+ ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
+ if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
+ urcu_bp_has_sys_membarrier = 1;
+ }
initialized = 1;
}
mutex_unlock(&init_lock);