Add test for rcu_assign_pointer()

[urcu.git] / urcu-qsbr-static.h

diff --git a/urcu-qsbr-static.h b/urcu-qsbr-static.h
index c0467cd0e1606c87a522e56d2299716cf6402b3e..d53a1f4919569e5ada46b6fd3ff83bc8bded341f 100644 (file)
--- a/urcu-qsbr-static.h
+++ b/urcu-qsbr-static.h
@@ -33,9 +33,13 @@
 #include <pthread.h>
 #include <assert.h>
 #include <limits.h>
+#include <syscall.h>
+#include <unistd.h>
 
-#include <compiler.h>
-#include <arch.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+#include <urcu/arch_uatomic.h>
+#include <urcu/list.h>
 
 /*
  * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
@@ -87,6 +91,10 @@
                                (_________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
@@ -97,11 +105,16 @@
 
 /*
  * If a reader is really non-cooperative and refuses to commit its
- * rcu_reader_qs_gp count to memory (there is no barrier in the reader
+ * urcu_reader.ctr count to memory (there is no barrier in the reader
  * per-se), kick it after a few loops waiting for it.
  */
 #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
@@ -171,7 +184,29 @@ static inline void reader_barrier()
  */
 extern unsigned long urcu_gp_ctr;
 
-extern unsigned long __thread rcu_reader_qs_gp;
+struct urcu_reader {
+       /* Data used by both reader and synchronize_rcu() */
+       unsigned long ctr;
+       /* Data used for registry */
+       struct list_head head __attribute__((aligned(CACHE_LINE_SIZE)));
+       pthread_t tid;
+};
+
+extern struct urcu_reader __thread urcu_reader;
+
+extern int gp_futex;
+
+/*
+ * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
+ */
+static inline void wake_up_gp(void)
+{
+       if (unlikely(uatomic_read(&gp_futex) == -1)) {
+               uatomic_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)
@@ -197,7 +232,7 @@ static inline int rcu_gp_ongoing(unsigned long *value)
 
 static inline void _rcu_read_lock(void)
 {
-       rcu_assert(rcu_reader_qs_gp);
+       rcu_assert(urcu_reader.ctr);
 }
 
 static inline void _rcu_read_unlock(void)
@@ -207,19 +242,23 @@ static inline void _rcu_read_unlock(void)
 static inline void _rcu_quiescent_state(void)
 {
        smp_mb();       
-       _STORE_SHARED(rcu_reader_qs_gp, _LOAD_SHARED(urcu_gp_ctr));
+       _STORE_SHARED(urcu_reader.ctr, _LOAD_SHARED(urcu_gp_ctr));
+       smp_mb();       /* write urcu_reader.ctr before read futex */
+       wake_up_gp();
        smp_mb();
 }
 
 static inline void _rcu_thread_offline(void)
 {
        smp_mb();
-       STORE_SHARED(rcu_reader_qs_gp, 0);
+       STORE_SHARED(urcu_reader.ctr, 0);
+       smp_mb();       /* write urcu_reader.ctr before read futex */
+       wake_up_gp();
 }
 
 static inline void _rcu_thread_online(void)
 {
-       _STORE_SHARED(rcu_reader_qs_gp, LOAD_SHARED(urcu_gp_ctr));
+       _STORE_SHARED(urcu_reader.ctr, LOAD_SHARED(urcu_gp_ctr));
        smp_mb();
 }
 
@@ -257,7 +296,7 @@ static inline void _rcu_thread_online(void)
                if (!__builtin_constant_p(_new) ||      \
                    ((_new) != NULL))                   \
                        wmb();                          \
-               cmpxchg(p, old, _new);                  \
+               uatomic_cmpxchg(p, old, _new);          \
        })
 
 /**
@@ -271,7 +310,7 @@ static inline void _rcu_thread_online(void)
                if (!__builtin_constant_p(v) ||         \
                    ((v) != NULL))                      \
                        wmb();                          \
-               xchg(p, v);                             \
+               uatomic_xchg(p, v);                     \
        })
 
 /*