X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=src%2Furcu-bp.c;h=ebe96c57da9630d3e43168ee32fa96da95277bfa;hp=4b4fe45b2c4bcaefe3dde281d0074f87caf0bc6b;hb=2f6618651c31c05ba1adbb5cdcf0d92980c38f38;hpb=6893800a4d1cc14dff0395ddcd660a5138db183d

diff --git a/src/urcu-bp.c b/src/urcu-bp.c
index 4b4fe45..ebe96c5 100644
--- a/src/urcu-bp.c
+++ b/src/urcu-bp.c
@@ -111,7 +111,9 @@ void __attribute__((constructor)) rcu_bp_init(void);
 static
 void __attribute__((destructor)) rcu_bp_exit(void);
 
+#ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
 int urcu_bp_has_sys_membarrier;
+#endif
 
 /*
  * rcu_gp_lock ensures mutual exclusion between threads calling
@@ -372,7 +374,8 @@ void expand_arena(struct registry_arena *arena)
 			sizeof(struct registry_chunk)
 			+ sizeof(struct rcu_reader));
 		new_chunk_len = ARENA_INIT_ALLOC;
-		new_chunk = mmap(NULL, new_chunk_len,
+		new_chunk = (struct registry_chunk *) mmap(NULL,
+			new_chunk_len,
 			PROT_READ | PROT_WRITE,
 			MAP_ANONYMOUS | MAP_PRIVATE,
 			-1, 0);
@@ -406,7 +409,8 @@ void expand_arena(struct registry_arena *arena)
 	}
 
 	/* Remap did not succeed, we need to add a new chunk. */
-	new_chunk = mmap(NULL, new_chunk_len,
+	new_chunk = (struct registry_chunk *) mmap(NULL,
+		new_chunk_len,
 		PROT_READ | PROT_WRITE,
 		MAP_ANONYMOUS | MAP_PRIVATE,
 		-1, 0);
@@ -578,6 +582,27 @@ void urcu_bp_thread_exit_notifier(void *rcu_key)
 	rcu_bp_unregister(rcu_key);
 }
 
+#ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
+static
+void rcu_sys_membarrier_status(int available)
+{
+	if (!available)
+		abort();
+}
+#else
+static
+void rcu_sys_membarrier_status(int available)
+{
+	/*
+	 * membarrier has blocking behavior, which changes the
+	 * application behavior too much compared to using barriers when
+	 * synchronize_rcu is used repeatedly (without using call_rcu).
+	 * Don't use membarrier for now, unless its use has been
+	 * explicitly forced when building liburcu.
+	 */
+}
+#endif
+
 static
 void rcu_bp_init(void)
 {
@@ -590,9 +615,8 @@ void rcu_bp_init(void)
 		if (ret)
 			abort();
 		ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
-		if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
-			urcu_bp_has_sys_membarrier = 1;
-		}
+		rcu_sys_membarrier_status(ret >= 0
+				&& (ret & MEMBARRIER_CMD_SHARED));
 		initialized = 1;
 	}
 	mutex_unlock(&init_lock);
@@ -608,7 +632,7 @@ void rcu_bp_exit(void)
 
 		cds_list_for_each_entry_safe(chunk, tmp,
 				&registry_arena.chunk_list, node) {
-			munmap(chunk, chunk->data_len
+			munmap((void *) chunk, chunk->data_len
 					+ sizeof(struct registry_chunk));
 		}
 		CDS_INIT_LIST_HEAD(&registry_arena.chunk_list);