X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=c210a1341ade8a189752417249bb47bca73a03aa;hp=2a225c4ed19d4c626b8f7fb9af5efa702bf3f371;hb=538d7df5086144837beb7a9c1e2a94eb637b9904;hpb=8a5fb4c96a1e49623fd9358a048b2cfec3a917f8

diff --git a/urcu.c b/urcu.c
index 2a225c4..c210a13 100644
--- 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 */