*
* Userspace RCU header.
*
- * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu.h for linking
- * dynamically with the userspace rcu library.
+ * TO BE INCLUDED ONLY IN CODE THAT IS TO BE RECOMPILED ON EACH LIBURCU
+ * RELEASE. See urcu.h for linking dynamically with the userspace rcu library.
*
* Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
* Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
#include <pthread.h>
#include <unistd.h>
-#define YIELD_READ (1 << 0)
-#define YIELD_WRITE (1 << 1)
+#define RCU_YIELD_READ (1 << 0)
+#define RCU_YIELD_WRITE (1 << 1)
/*
* Updates without RCU_MB are much slower. Account this in
/* maximum sleep delay, in us */
#define MAX_SLEEP 50
-extern unsigned int yield_active;
-extern DECLARE_URCU_TLS(unsigned int, rand_yield);
+extern unsigned int rcu_yield_active;
+extern DECLARE_URCU_TLS(unsigned int, rcu_rand_yield);
-static inline void debug_yield_read(void)
+static inline void rcu_debug_yield_read(void)
{
- if (yield_active & YIELD_READ)
- if (rand_r(&URCU_TLS(rand_yield)) & 0x1)
- usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP);
+ 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 debug_yield_write(void)
+static inline void rcu_debug_yield_write(void)
{
- if (yield_active & YIELD_WRITE)
- if (rand_r(&URCU_TLS(rand_yield)) & 0x1)
- usleep(rand_r(&URCU_TLS(rand_yield)) % MAX_SLEEP);
+ 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 debug_yield_init(void)
+static inline void rcu_debug_yield_init(void)
{
- URCU_TLS(rand_yield) = time(NULL) ^ pthread_self();
+ URCU_TLS(rcu_rand_yield) = time(NULL) ^ (unsigned long) pthread_self();
}
#else
-static inline void debug_yield_read(void)
+static inline void rcu_debug_yield_read(void)
{
}
-static inline void debug_yield_write(void)
+static inline void rcu_debug_yield_write(void)
{
}
-static inline void debug_yield_init(void)
+static inline void rcu_debug_yield_init(void)
{
}
((v ^ rcu_gp_ctr) & RCU_GP_CTR_PHASE);
}
+/*
+ * 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
+ * _rcu_read_lock() happen before the subsequent read-side critical section.
+ */
+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();
+ } else
+ _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp + RCU_GP_COUNT);
+}
+
+/*
+ * Enter an RCU read-side critical section.
+ *
+ * The first cmm_barrier() call ensures that the compiler does not reorder
+ * the body of _rcu_read_lock() with a mutex.
+ *
+ * This function and its helper are both less than 10 lines long. The
+ * intent is that this function meets the 10-line criterion in LGPL,
+ * allowing this function to be invoked directly from non-LGPL code.
+ */
static inline void _rcu_read_lock(void)
{
long tmp;
- /* Check if registered */
if (caa_unlikely(!URCU_TLS(rcu_reader)))
- rcu_bp_register();
-
+ rcu_bp_register(); /* If not yet registered. */
cmm_barrier(); /* Ensure the compiler does not reorder us with mutex */
tmp = URCU_TLS(rcu_reader)->ctr;
- /*
- * rcu_gp_ctr is
- * RCU_GP_COUNT | (~RCU_GP_CTR_PHASE or RCU_GP_CTR_PHASE)
- */
- if (caa_likely(!(tmp & RCU_GP_CTR_NEST_MASK))) {
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, _CMM_LOAD_SHARED(rcu_gp_ctr));
- /*
- * Set active readers count for outermost nesting level before
- * accessing the pointer.
- */
- cmm_smp_mb();
- } else {
- _CMM_STORE_SHARED(URCU_TLS(rcu_reader)->ctr, tmp + RCU_GP_COUNT);
- }
+ _rcu_read_lock_update(tmp);
}
+/*
+ * Exit an RCU read-side critical section. This function is less than
+ * 10 lines of code, and is intended to be usable by non-LGPL code, as
+ * called out in LGPL.
+ */
static inline void _rcu_read_unlock(void)
{
/*