X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=4104a3f563fd400709e7e7d3e8a73a1437321d88;hb=4d3b06fe77725f267b85502dbeb51991296b9389;hp=1a1f7181df22c262c4e3bb5a4546cac97ee95793;hpb=dde70ea0d552734c58d9776bb74b73b6314b9168;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 1a1f7181..4104a3f5 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -78,6 +78,12 @@ static sem_t constructor_wait;
  */
 static int sem_count = { 2 };
 
+/*
+ * Counting nesting within lttng-ust. Used to ensure that calling fork()
+ * from liblttng-ust does not execute the pre/post fork handlers.
+ */
+static int __thread lttng_ust_nest_count;
+
 /*
  * Info about socket and associated listener thread.
  */
@@ -130,6 +136,15 @@ extern void ltt_ring_buffer_client_overwrite_exit(void);
 extern void ltt_ring_buffer_client_discard_exit(void);
 extern void ltt_ring_buffer_metadata_client_exit(void);
 
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+static
+void lttng_fixup_nest_count_tls(void)
+{
+	asm volatile ("" : : "m" (lttng_ust_nest_count));
+}
+
 static
 int setup_local_apps(void)
 {
@@ -481,7 +496,9 @@ int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
 	 * If the open failed because the file did not exist, try
 	 * creating it ourself.
 	 */
+	lttng_ust_nest_count++;
 	pid = fork();
+	lttng_ust_nest_count--;
 	if (pid > 0) {
 		int status;
 
@@ -864,6 +881,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	lttng_fixup_event_tls();
 	lttng_fixup_ringbuffer_tls();
 	lttng_fixup_vtid_tls();
+	lttng_fixup_nest_count_tls();
 
 	/*
 	 * We want precise control over the order in which we construct
@@ -895,15 +913,20 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	sigfillset(&sig_all_blocked);
 	ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
 	if (ret) {
-		PERROR("pthread_sigmask: %s", strerror(ret));
+		ERR("pthread_sigmask: %s", strerror(ret));
 	}
 
 	ret = pthread_create(&global_apps.ust_listener, NULL,
 			ust_listener_thread, &global_apps);
-
+	if (ret) {
+		ERR("pthread_create global: %s", strerror(ret));
+	}
 	if (local_apps.allowed) {
 		ret = pthread_create(&local_apps.ust_listener, NULL,
 				ust_listener_thread, &local_apps);
+		if (ret) {
+			ERR("pthread_create local: %s", strerror(ret));
+		}
 	} else {
 		handle_register_done(&local_apps);
 	}
@@ -911,7 +934,7 @@ void __attribute__((constructor)) lttng_ust_init(void)
 	/* Restore original signal mask in parent */
 	ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
 	if (ret) {
-		PERROR("pthread_sigmask: %s", strerror(ret));
+		ERR("pthread_sigmask: %s", strerror(ret));
 	}
 
 	switch (timeout_mode) {
@@ -987,12 +1010,14 @@ void __attribute__((destructor)) lttng_ust_exit(void)
 	/* cancel threads */
 	ret = pthread_cancel(global_apps.ust_listener);
 	if (ret) {
-		ERR("Error cancelling global ust listener thread");
+		ERR("Error cancelling global ust listener thread: %s",
+			strerror(ret));
 	}
 	if (local_apps.allowed) {
 		ret = pthread_cancel(local_apps.ust_listener);
 		if (ret) {
-			ERR("Error cancelling local ust listener thread");
+			ERR("Error cancelling local ust listener thread: %s",
+				strerror(ret));
 		}
 	}
 	/*
@@ -1024,6 +1049,8 @@ void ust_before_fork(sigset_t *save_sigset)
 	sigset_t all_sigs;
 	int ret;
 
+	if (lttng_ust_nest_count)
+		return;
 	/* Disable signals */
 	sigfillset(&all_sigs);
 	ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
@@ -1049,6 +1076,8 @@ static void ust_after_fork_common(sigset_t *restore_sigset)
 
 void ust_after_fork_parent(sigset_t *restore_sigset)
 {
+	if (lttng_ust_nest_count)
+		return;
 	DBG("process %d", getpid());
 	rcu_bp_after_fork_parent();
 	/* Release mutexes and reenable signals */
@@ -1066,6 +1095,8 @@ void ust_after_fork_parent(sigset_t *restore_sigset)
  */
 void ust_after_fork_child(sigset_t *restore_sigset)
 {
+	if (lttng_ust_nest_count)
+		return;
 	DBG("process %d", getpid());
 	/* Release urcu mutexes */
 	rcu_bp_after_fork_child();