X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=256cbdc625ef19f6da306124542a6e0a08ab593f;hb=9e16611568f395e9b646ecee0906a5a1e3bb7110;hp=597712bc1313057daaa4ee32730b46c3951eb78d;hpb=86e361632f8cb161d6cf3cfd1bb964a7f7fa0a52;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 597712bc..256cbdc6 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -34,6 +34,7 @@
 #include <time.h>
 #include <assert.h>
 #include <signal.h>
+#include <dlfcn.h>
 #include <urcu/uatomic.h>
 #include <urcu/futex.h>
 #include <urcu/compiler.h>
@@ -51,6 +52,7 @@
 #include "lttng-tracer-core.h"
 #include "compat.h"
 #include "../libringbuffer/tlsfixup.h"
+#include "lttng-ust-baddr.h"
 
 /*
  * Has lttng ust comm constructor been called ?
@@ -106,6 +108,8 @@ struct sock_info {
 
 	char wait_shm_path[PATH_MAX];
 	char *wait_shm_mmap;
+	/* Keep track of lazy state dump not performed yet. */
+	int statedump_pending;
 };
 
 /* Socket from app (connect) to session daemon (listen) for communication */
@@ -122,6 +126,8 @@ struct sock_info global_apps = {
 	.notify_socket = -1,
 
 	.wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
+
+	.statedump_pending = 0,
 };
 
 /* TODO: allow global_apps_sock_path override */
@@ -135,6 +141,8 @@ struct sock_info local_apps = {
 
 	.socket = -1,
 	.notify_socket = -1,
+
+	.statedump_pending = 0,
 };
 
 static int wait_poll_fallback;
@@ -380,6 +388,28 @@ int handle_register_done(struct sock_info *sock_info)
 	return 0;
 }
 
+/*
+ * Only execute pending statedump after the constructor semaphore has
+ * been posted by each listener thread. This means statedump will only
+ * be performed after the "registration done" command is received from
+ * each session daemon the application is connected to.
+ *
+ * This ensures we don't run into deadlock issues with the dynamic
+ * loader mutex, which is held while the constructor is called and
+ * waiting on the constructor semaphore. All operations requiring this
+ * dynamic loader lock need to be postponed using this mechanism.
+ */
+static
+void handle_pending_statedump(struct sock_info *sock_info)
+{
+	int ctor_passed = sock_info->constructor_sem_posted;
+
+	if (ctor_passed && sock_info->statedump_pending) {
+		sock_info->statedump_pending = 0;
+		lttng_handle_pending_statedump(sock_info);
+	}
+}
+
 static
 int handle_message(struct sock_info *sock_info,
 		int sock, struct ustcomm_ust_msg *lum)
@@ -698,6 +728,14 @@ end:
 
 error:
 	ust_unlock();
+
+	/*
+	 * Performed delayed statedump operations outside of the UST
+	 * lock. We need to take the dynamic loader lock before we take
+	 * the UST lock internally within handle_pending_statedump().
+	  */
+	handle_pending_statedump(sock_info);
+
 	return ret;
 }
 
@@ -1519,3 +1557,9 @@ void ust_after_fork_child(sigset_t *restore_sigset)
 	ust_after_fork_common(restore_sigset);
 	lttng_ust_init();
 }
+
+void lttng_ust_sockinfo_session_enabled(void *owner)
+{
+	struct sock_info *sock_info = owner;
+	sock_info->statedump_pending = 1;
+}