Move xmlInitThreads()/xmlCleanupThreads() calls

xmlInitThreads() and xmlCleanupThreads() are called from within
named_statschannels_configure() and named_statschannels_shutdown(),
respectively.  Both of these functions are executed by worker threads,
not the main named thread.  This causes ASAN to report memory leaks like
the following one upon shutdown (as long as named is asked to produce
any XML output over its configured statistics channels during its
lifetime):

    Direct leak of 968 byte(s) in 1 object(s) allocated from:
        #0 0x7f677c249cd8 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:153
        #1 0x7f677bc1838f in xmlGetGlobalState (/usr/lib/libxml2.so.2+0xa838f)

The data mentioned in the above report is a libxml2 state structure
stored as thread-specific data.  Such chunks of memory are automatically
released (by a destructor passed to pthread_key_create() by libxml2)
whenever a thread that allocated a given chunk exits.  However, if
xmlCleanupThreads() is called by a given thread before it exits, the
destructor will not be invoked (due to xmlCleanupThreads() calling
pthread_key_delete()) and ASAN will report a memory leak.  Thus,
xmlInitThreads() and xmlCleanupThreads() must not be called from worker
threads.  Since xmlInitThreads() must be called on Windows in order for
libxml2 to work at all, move xmlInitThreads() and xmlCleanupThreads()
calls to the main named thread (which does not produce any XML output
itself) in order to prevent the memory leak from being reported by ASAN.

diff --git a/bin/named/main.c b/bin/named/main.c
index df9ec70f3d5ac3d81d1a19e009b0bcc8e116a45f..10e4f536a0c734f6654b979b6860912fbb0d7b0e 100644 (file)
--- a/bin/named/main.c
+++ b/bin/named/main.c
@@ -1443,6 +1443,10 @@ main(int argc, char *argv[]) {
        setvbuf(stderr, NULL, _IOFBF, BUFSIZ);
 #endif
 
+#ifdef HAVE_LIBXML2
+       xmlInitThreads();
+#endif /* HAVE_LIBXML2 */
+
        /*
         * Record version in core image.
         * strings named.core | grep "named version:"
@@ -1575,6 +1579,10 @@ main(int argc, char *argv[]) {
 
        named_os_shutdown();
 
+#ifdef HAVE_LIBXML2
+       xmlCleanupThreads();
+#endif /* HAVE_LIBXML2 */
+
 #ifdef HAVE_GPERFTOOLS_PROFILER
        ProfilerStop();
 #endif

diff --git a/bin/named/statschannel.c b/bin/named/statschannel.c
index c125b659cfb9158da1ca9490add93a0c867ae097..841741a9434b8eab51b9d449a14873822cc1d67f 100644 (file)
--- a/bin/named/statschannel.c
+++ b/bin/named/statschannel.c
@@ -3593,10 +3593,6 @@ named_statschannels_configure(named_server_t *server, const cfg_obj_t *config,
 
        ISC_LIST_INIT(new_listeners);
 
-#ifdef HAVE_LIBXML2
-       xmlInitThreads();
-#endif /* HAVE_LIBXML2 */
-
        /*
         * Get the list of named.conf 'statistics-channels' statements.
         */
@@ -3729,10 +3725,6 @@ named_statschannels_shutdown(named_server_t *server) {
                ISC_LIST_UNLINK(server->statschannels, listener, link);
                shutdown_listener(listener);
        }
-
-#ifdef HAVE_LIBXML2
-       xmlCleanupThreads();
-#endif /* HAVE_LIBXML2 */
 }
 
 isc_result_t