#include <urcu/uatomic.h>
#include <urcu/list.h>
#include <urcu/tls-compat.h>
+#include <urcu/debug.h>
/*
* This code section can only be included in LGPL 2.1 compatible source code.
extern "C" {
#endif
-#ifdef DEBUG_RCU
-#define rcu_assert(args...) assert(args)
-#else
-#define rcu_assert(args...)
-#endif
-
enum rcu_state {
RCU_READER_ACTIVE_CURRENT,
RCU_READER_ACTIVE_OLD,
RCU_READER_INACTIVE,
};
-#ifdef DEBUG_YIELD
-#include <sched.h>
-#include <time.h>
-#include <pthread.h>
-#include <unistd.h>
-
-#define RCU_YIELD_READ (1 << 0)
-#define RCU_YIELD_WRITE (1 << 1)
-
-/*
- * Updates without RCU_MB are much slower. Account this in
- * the delay.
- */
-/* maximum sleep delay, in us */
-#define MAX_SLEEP 50
-
-extern unsigned int rcu_yield_active;
-extern DECLARE_URCU_TLS(unsigned int, rcu_rand_yield);
-
-static inline void rcu_debug_yield_read(void)
-{
- if (rcu_yield_active & RCU_YIELD_READ)
- if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1)
- usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP);
-}
-
-static inline void rcu_debug_yield_write(void)
-{
- if (rcu_yield_active & RCU_YIELD_WRITE)
- if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1)
- usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP);
-}
-
-static inline void rcu_debug_yield_init(void)
-{
- URCU_TLS(rcu_rand_yield) = time(NULL) ^ (unsigned long) pthread_self();
-}
-#else
-static inline void rcu_debug_yield_read(void)
-{
-}
-
-static inline void rcu_debug_yield_write(void)
-{
-}
-
-static inline void rcu_debug_yield_init(void)
-{
-
-}
-#endif
-
/*
* The trick here is that RCU_GP_CTR_PHASE must be a multiple of 8 so we can use a
* full 8-bits, 16-bits or 32-bits bitmask for the lower order bits.
*/
extern void rcu_bp_register(void);
-/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
- */
-extern unsigned long rcu_gp_ctr;
+struct rcu_gp {
+ /*
+ * Global grace period counter.
+ * Contains the current RCU_GP_CTR_PHASE.
+ * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path.
+ * Written to only by writer with mutex taken.
+ * Read by both writer and readers.
+ */
+ unsigned long ctr;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
+extern struct rcu_gp rcu_gp;
struct rcu_reader {
/* Data used by both reader and synchronize_rcu() */
*/
extern DECLARE_URCU_TLS(struct rcu_reader *, rcu_reader);
+extern int urcu_bp_has_sys_membarrier;
+
+static inline void urcu_bp_smp_mb_slave(void)
+{
+ if (caa_likely(urcu_bp_has_sys_membarrier))
+ cmm_barrier();
+ else
+ cmm_smp_mb();
+}
+
static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
{
unsigned long v;
v = CMM_LOAD_SHARED(*ctr);
if (!(v & RCU_GP_CTR_NEST_MASK))
return RCU_READER_INACTIVE;
- if (!((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE))
+ if (!((v ^ rcu_gp.ctr) & RCU_GP_CTR_PHASE))
return RCU_READER_ACTIVE_CURRENT;
return RCU_READER_ACTIVE_OLD;
}
/*
- * Helper for _rcu_read_lock(). The format of rcu_gp_ctr (as well as
+ * Helper for _rcu_read_lock(). The format of rcu_gp.ctr (as well as
* the per-thread rcu_reader.ctr) has the upper bits containing a count of
* _rcu_read_lock() nesting, and a lower-order bit that contains either zero
* or RCU_GP_CTR_PHASE. The smp_mb_slave() ensures that the accesses in
static inline void _rcu_read_lock_update(unsigned long tmp)
{
if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
- cmm_smp_mb();
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp.ctr));
+ urcu_bp_smp_mb_slave();
} else
_CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp + RCU_GP_COUNT);
}
rcu_bp_register(); /* If not yet registered. */
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
tmp = URCU_TLS(rcu_reader)->ctr;
+ urcu_assert((tmp & RCU_GP_CTR_NEST_MASK) != RCU_GP_CTR_NEST_MASK);
_rcu_read_lock_update(tmp);
}
*/
static inline void _rcu_read_unlock(void)
{
- /*
- * Finish using rcu before decrementing the pointer.
- */
- cmm_smp_mb();
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, URCU_TLS(rcu_reader)->ctr - RCU_GP_COUNT);
+ unsigned long tmp;
+
+ tmp = URCU_TLS(rcu_reader)->ctr;
+ urcu_assert(tmp & RCU_GP_CTR_NEST_MASK);
+ /* Finish using rcu before decrementing the pointer. */
+ urcu_bp_smp_mb_slave();
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp - RCU_GP_COUNT);
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
}