urcu call_rcu: Use RCU read-side protection for per-cpu call_rcu data

[urcu.git] / urcu-bp.c

diff --git a/urcu-bp.c b/urcu-bp.c
index db2aef0c57b8ef397095cd71d6c12ded119bb9ec..4c0ab54a28e71b47947905d6f5f42354de0135cd 100644 (file)
--- a/urcu-bp.c
+++ b/urcu-bp.c
@@ -24,6 +24,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
@@ -35,14 +36,58 @@
 #include <unistd.h>
 #include <sys/mman.h>
 
-#include "urcu-bp-static.h"
+#include "urcu/wfqueue.h"
+#include "urcu/map/urcu-bp.h"
+#include "urcu/static/urcu-bp.h"
+#include "urcu-pointer.h"
+
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
+#undef _LGPL_SOURCE
 #include "urcu-bp.h"
+#define _LGPL_SOURCE
+
+#ifndef MAP_ANONYMOUS
+#define MAP_ANONYMOUS MAP_ANON
+#endif
+
+#ifndef __linux__
+
+#define MREMAP_MAYMOVE 1
+#define MREMAP_FIXED   2
+
+/*
+ * mremap wrapper for non-Linux systems. Maps a RW, anonymous private mapping.
+ * This is not generic.
+*/
+void *mremap(void *old_address, size_t old_size, size_t new_size, int flags)
+{
+       void *new_address;
+
+       assert(flags & MREMAP_MAYMOVE);
+       assert(!(flags & MREMAP_FIXED));
+       new_address = mmap(old_address, new_size,
+                          PROT_READ | PROT_WRITE,
+                          MAP_ANONYMOUS | MAP_PRIVATE,
+                          -1, 0);
+       if (new_address == MAP_FAILED)
+               return MAP_FAILED;
+       if (old_address) {
+               memcpy(new_address, old_address, old_size);
+               munmap(old_address, old_size);
+       }
+       return new_address;
+}
+#endif
 
 /* Sleep delay in us */
 #define RCU_SLEEP_DELAY                1000
 #define ARENA_INIT_ALLOC       16
 
+/*
+ * Active attempts to check for reader Q.S. before calling sleep().
+ */
+#define RCU_QS_ACTIVE_ATTEMPTS 100
+
 void __attribute__((destructor)) rcu_bp_exit(void);
 
 static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
@@ -76,6 +121,9 @@ struct registry_arena {
 
 static struct registry_arena registry_arena;
 
+/* Saved fork signal mask, protected by rcu_gp_lock */
+static sigset_t saved_fork_signal_mask;
+
 static void rcu_gc_registry(void);
 
 static void mutex_lock(pthread_mutex_t *mutex)
@@ -245,7 +293,6 @@ static void resize_arena(struct registry_arena *arena, size_t len)
        if (new_arena == arena->p)
                return;
 
-       memcpy(new_arena, arena->p, arena->len);
        bzero(new_arena + arena->len, len - arena->len);
        arena->p = new_arena;
 }
@@ -258,7 +305,7 @@ static void add_thread(void)
        if (registry_arena.len
            < registry_arena.used + sizeof(struct rcu_reader))
                resize_arena(&registry_arena,
-               max(registry_arena.len << 1, ARENA_INIT_ALLOC));
+               caa_max(registry_arena.len << 1, ARENA_INIT_ALLOC));
        /*
         * Find a free spot.
         */
@@ -327,7 +374,52 @@ end:
        assert(!ret);
 }
 
-void rcu_bp_exit()
+void rcu_bp_exit(void)
+{
+       if (registry_arena.p)
+               munmap(registry_arena.p, registry_arena.len);
+}
+
+/*
+ * Holding the rcu_gp_lock across fork will make sure we fork() don't race with
+ * a concurrent thread executing with this same lock held. This ensures that the
+ * registry is in a coherent state in the child.
+ */
+void rcu_bp_before_fork(void)
+{
+       sigset_t newmask, oldmask;
+       int ret;
+
+       ret = sigemptyset(&newmask);
+       assert(!ret);
+       ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask);
+       assert(!ret);
+       mutex_lock(&rcu_gp_lock);
+       saved_fork_signal_mask = oldmask;
+}
+
+void rcu_bp_after_fork_parent(void)
+{
+       sigset_t oldmask;
+       int ret;
+
+       oldmask = saved_fork_signal_mask;
+       mutex_unlock(&rcu_gp_lock);
+       ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
+       assert(!ret);
+}
+
+void rcu_bp_after_fork_child(void)
 {
-       munmap(registry_arena.p, registry_arena.len);
+       sigset_t oldmask;
+       int ret;
+
+       rcu_gc_registry();
+       oldmask = saved_fork_signal_mask;
+       mutex_unlock(&rcu_gp_lock);
+       ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
+       assert(!ret);
 }
+
+#include "urcu-call-rcu-impl.h"
+#include "urcu-defer-impl.h"