Remove libust-initializer

[lttng-ust.git] / libust / lttng-ust-comm.c

diff --git a/libust/lttng-ust-comm.c b/libust/lttng-ust-comm.c
index 0f7bc34b6ed14200af50f44731c89ca1ee1a4457..1e4031be273fcbcc7a29d397ab0bb8db3bbcfa22 100644 (file)
--- a/libust/lttng-ust-comm.c
+++ b/libust/lttng-ust-comm.c
@@ -28,6 +28,7 @@
 #include <semaphore.h>
 #include <time.h>
 #include <assert.h>
+#include <signal.h>
 #include <urcu/uatomic.h>
 
 #include <lttng-ust-comm.h>
@@ -35,6 +36,7 @@
 #include <ust/lttng-ust-abi.h>
 #include <ust/tracepoint.h>
 #include <ust/tracepoint-internal.h>
+#include <ust/ust.h>
 
 /*
  * Has lttng ust comm constructor been called ?
@@ -541,3 +543,58 @@ void __attribute__((destructor)) lttng_ust_exit(void)
        ltt_ring_buffer_metadata_client_exit();
        exit_tracepoint();
 }
+
+/*
+ * We exclude the worker threads across fork and clone (except
+ * CLONE_VM), because these system calls only keep the forking thread
+ * running in the child.  Therefore, we don't want to call fork or clone
+ * in the middle of an tracepoint or ust tracing state modification.
+ * Holding this mutex protects these structures across fork and clone.
+ */
+void ust_before_fork(ust_fork_info_t *fork_info)
+{
+       /*
+        * Disable signals. This is to avoid that the child intervenes
+        * before it is properly setup for tracing. It is safer to
+        * disable all signals, because then we know we are not breaking
+        * anything by restoring the original mask.
+         */
+       sigset_t all_sigs;
+       int ret;
+
+       /* Disable signals */
+       sigfillset(&all_sigs);
+       ret = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
+       if (ret == -1) {
+               PERROR("sigprocmask");
+       }
+       pthread_mutex_lock(&lttng_ust_comm_mutex);
+       rcu_bp_before_fork();
+}
+
+static void ust_after_fork_common(ust_fork_info_t *fork_info)
+{
+       int ret;
+
+       pthread_mutex_unlock(&lttng_ust_comm_mutex);
+       /* Restore signals */
+       ret = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
+       if (ret == -1) {
+               PERROR("sigprocmask");
+       }
+}
+
+void ust_after_fork_parent(ust_fork_info_t *fork_info)
+{
+       rcu_bp_after_fork_parent();
+       /* Release mutexes and reenable signals */
+       ust_after_fork_common(fork_info);
+}
+
+void ust_after_fork_child(ust_fork_info_t *fork_info)
+{
+       /* Release urcu mutexes */
+       rcu_bp_after_fork_child();
+       /* Release mutexes and reenable signals */
+       ust_after_fork_common(fork_info);
+}