urcu.c: declare noop urcu_init() function non-static

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index 2a225c4ed19d4c626b8f7fb9af5efa702bf3f371..c210a1341ade8a189752417249bb47bca73a03aa 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -36,8 +36,14 @@
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #include "urcu.h"
 
+#ifndef CONFIG_URCU_AVOID_SIGNALS
 void __attribute__((constructor)) urcu_init(void);
 void __attribute__((destructor)) urcu_exit(void);
+#else
+void urcu_init(void)
+{
+}
+#endif
 
 int init_done;
 
@@ -121,7 +127,7 @@ static void switch_next_urcu_qparity(void)
        STORE_SHARED(urcu_gp_ctr, urcu_gp_ctr ^ RCU_GP_CTR_BIT);
 }
 
-#ifdef DEBUG_FULL_MB
+#ifdef CONFIG_URCU_AVOID_SIGNALS
 #ifdef HAS_INCOHERENT_CACHES
 static void force_mb_single_thread(struct reader_registry *index)
 {
@@ -133,7 +139,7 @@ static void force_mb_all_threads(void)
 {
        smp_mb();
 }
-#else /* #ifdef DEBUG_FULL_MB */
+#else /* #ifdef CONFIG_URCU_AVOID_SIGNALS */
 #ifdef HAS_INCOHERENT_CACHES
 static void force_mb_single_thread(struct reader_registry *index)
 {
@@ -200,7 +206,7 @@ static void force_mb_all_threads(void)
        }
        smp_mb();       /* read ->need_mb before ending the barrier */
 }
-#endif /* #else #ifdef DEBUG_FULL_MB */
+#endif /* #else #ifdef CONFIG_URCU_AVOID_SIGNALS */
 
 void wait_for_quiescent_state(void)
 {
@@ -254,12 +260,11 @@ void synchronize_rcu(void)
         */
 
        /*
-        * Current RCU formal verification model assumes sequential execution of
-        * the write-side. Add core synchronization instructions. Can be removed
-        * if the formal model is extended to prove that reordering is still
-        * correct.
+        * Adding a smp_mb() which is _not_ formally required, but makes the
+        * model easier to understand. It does not have a big performance impact
+        * anyway, given this is the write-side.
         */
-       sync_core();    /* Formal model assumes serialized execution */
+       smp_mb();
 
        /*
         * Wait for previous parity to be empty of readers.
@@ -274,7 +279,12 @@ void synchronize_rcu(void)
         * Ensured by STORE_SHARED and LOAD_SHARED.
         */
 
-       sync_core();    /* Formal model assumes serialized execution */
+       /*
+        * Adding a smp_mb() which is _not_ formally required, but makes the
+        * model easier to understand. It does not have a big performance impact
+        * anyway, given this is the write-side.
+        */
+       smp_mb();
 
        switch_next_urcu_qparity();     /* 1 -> 0 */
 
@@ -286,7 +296,12 @@ void synchronize_rcu(void)
         * Ensured by STORE_SHARED and LOAD_SHARED.
         */
 
-       sync_core();    /* Formal model assumes serialized execution */
+       /*
+        * Adding a smp_mb() which is _not_ formally required, but makes the
+        * model easier to understand. It does not have a big performance impact
+        * anyway, given this is the write-side.
+        */
+       smp_mb();
 
        /*
         * Wait for previous parity to be empty of readers.
@@ -405,7 +420,7 @@ void rcu_unregister_thread(void)
        internal_urcu_unlock();
 }
 
-#ifndef DEBUG_FULL_MB
+#ifndef CONFIG_URCU_AVOID_SIGNALS
 static void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
 {
        /*
@@ -436,6 +451,8 @@ void urcu_init(void)
        init_done = 1;
 
        act.sa_sigaction = sigurcu_handler;
+       act.sa_flags = SA_SIGINFO | SA_RESTART;
+       sigemptyset(&act.sa_mask);
        ret = sigaction(SIGURCU, &act, NULL);
        if (ret) {
                perror("Error in sigaction");
@@ -456,4 +473,4 @@ void urcu_exit(void)
        assert(act.sa_sigaction == sigurcu_handler);
        free(registry);
 }
-#endif /* #ifndef DEBUG_FULL_MB */
+#endif /* #ifndef CONFIG_URCU_AVOID_SIGNALS */