* elf/Makefile: Add rules to build and run tst-thrlock.

* elf/tst-thrlock.c:  New file.

ChangeLog

@@ -5,6 +5,8 @@
 	(_dl_close): Call _dl_close_worker after locking and checking.
 	* elf/dl-open.c (_dl_open): Call _dl_close_worker instead of
 	_dl_close.
+	* elf/Makefile: Add rules to build and run tst-thrlock.
+	* elf/tst-thrlock.c:  New file.
 
 	[BZ #3426]
 	* stdlib/stdlib.h: Adjust comment for canonicalize_file_name to

elf/Makefile

@@ -171,7 +171,7 @@ tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-dlmopen1 tst-dlmopen2 tst-dlmopen3 \
 	 unload3 unload4 unload5 unload6 unload7 tst-global1 order2 \
 	 tst-audit1 tst-audit2 \
-	 tst-stackguard1 tst-addr1
+	 tst-stackguard1 tst-addr1 tst-thrlock
 #	 reldep9
 test-srcs = tst-pathopt
 tests-vis-yes = vismain
@@ -916,3 +916,5 @@ $(objpfx)tst-leaks1-mem: $(objpfx)tst-leaks1.out
 tst-leaks1-ENV = MALLOC_TRACE=$(objpfx)tst-leaks1.mtrace
 
 $(objpfx)tst-addr1: $(libdl)
+
+$(objpfx)tst-thrlock: $(libdl) $(shared-thread-library)

elf/dl-close.c

@@ -110,10 +110,6 @@ void
 _dl_close_worker (struct link_map *map)
 {
   Lmid_t ns = map->l_ns;
-  unsigned int i;
-
-  /* Acquire the lock.  */
-  __rtld_lock_lock_recursive (GL(dl_load_lock));
 
   /* One less direct use.  */
   --map->l_direct_opencount;
@@ -236,7 +232,7 @@ _dl_close_worker (struct link_map *map)
 #endif
   bool unload_any = false;
   unsigned int first_loaded = ~0;
-  for (i = 0; i < nloaded; ++i)
+  for (unsigned int i = 0; i < nloaded; ++i)
     {
       struct link_map *imap = maps[i];
 
@@ -472,7 +468,7 @@ _dl_close_worker (struct link_map *map)
 
   /* Check each element of the search list to see if all references to
      it are gone.  */
-  for (i = first_loaded; i < nloaded; ++i)
+  for (unsigned int i = first_loaded; i < nloaded; ++i)
     {
       struct link_map *imap = maps[i];
       if (!used[i])

elf/tst-thrlock.c

@@ -0,0 +1,55 @@
+#include <dlfcn.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <gnu/lib-names.h>
+
+static void *
+tf (void *arg)
+{
+  void *h = dlopen (LIBM_SO, RTLD_LAZY);
+  if (h == NULL)
+    {
+      printf ("dlopen failed: %s\n", dlerror ());
+      exit (1);
+    }
+  if (dlsym (h, "sin") == NULL)
+    {
+      printf ("dlsym failed: %s\n", dlerror ());
+      exit (1);
+    }
+  if (dlclose (h) != 0)
+    {
+      printf ("dlclose failed: %s\n", dlerror ());
+      exit (1);
+    }
+  return NULL;
+}
+
+int
+main (void)
+{
+#define N 10
+  pthread_t th[N];
+  for (int i = 0; i < N; ++i)
+    {
+      int e = pthread_create (&th[i], NULL, tf, NULL);
+      if (e != 0)
+	{
+	  printf ("pthread_create failed with %d (%s)\n", e, strerror (e));
+	  return 1;
+	}
+    }
+  for (int i = 0; i < N; ++i)
+    {
+      void *res;
+      int e = pthread_join (th[i], &res);
+      if (e != 0 || res != NULL)
+	{
+	  puts ("thread failed");
+	  return 1;
+	}
+    }
+  return 0;
+}