[PATCH] Run thread shutdown functions in an explicit order

[fweimer at redhat dot com (Florian Weimer)]

This removes the __libc_thread_subfreeres hook in favor of explict
calls.

2018-06-25  Florian Weimer  <fweimer@redhat.com>

	Run thread shutdown functions in an explicit order.
	* malloc/thread-freeres.c (__libc_thread_subfreeres): Remove hook
	definition.
	(__libc_thread_freeres): Call thread shutdown functions
	explicitly.
	* include/rpc/rpc.h (__rpc_thread_destroy): Add hidden attribute.
	* include/string.h (__strerror_thread_freeres): Declare.
	* malloc/arena.c (__malloc_arena_thread_freeres): Renamed from
	arena_thread_freeres.  No longer static.  Remove thread shutdown
	hook registration.
	* malloc/malloc-internal.h (__malloc_arena_thread_freeres):
	Declare.
	* resolv/res-close.c (__res_thread_freeres): Renamed from
	res_thread_freeres.  No longer static.  Remove thread shutdown
	hook registration.
	* resolv/resolv-internal.h (__res_thread_freeres): Declare.
	* resolv/resolv_conf.c (freeres): Remove incorrect section
	attribute.
	* string/strerror_l.c (__strerror_thread_freeres): Renamed from
	strerror_thread_freeres.  No longer static.  Remove thread
	shutdown hook registration.
	* sysdeps/mach/strerror_l.c (__strerror_thread_freeres): Likewise.
	* sunrpc/rpc_thread.c (__rpc_thread_destroy): Remove thread
	shutdown hook registration.
	* manual/memory.texi (Basic Allocation): Update comment.

diff --git a/include/rpc/rpc.h b/include/rpc/rpc.h
index 327d84319e..f5cee6caef 100644
--- a/include/rpc/rpc.h
+++ b/include/rpc/rpc.h
@@ -45,7 +45,7 @@ extern void __rpc_thread_svc_cleanup (void) attribute_hidden;
 extern void __rpc_thread_clnt_cleanup (void) attribute_hidden;
 extern void __rpc_thread_key_cleanup (void) attribute_hidden;
 
-extern void __rpc_thread_destroy (void);
+extern void __rpc_thread_destroy (void) attribute_hidden;
 
 __libc_tsd_define (extern, struct rpc_thread_variables *, RPC_VARS)
 
diff --git a/include/string.h b/include/string.h
index bb4922cbbe..4d622f1c03 100644
--- a/include/string.h
+++ b/include/string.h
@@ -50,6 +50,9 @@ extern int __ffs (int __i) __attribute__ ((const));
 
 extern char *__strerror_r (int __errnum, char *__buf, size_t __buflen);
 
+/* Called as part of the thread shutdown sequence.  */
+void __strerror_thread_freeres (void) attribute_hidden;
+
 /* Get _STRING_ARCH_unaligned.  */
 #include <string_private.h>
 #endif
diff --git a/malloc/arena.c b/malloc/arena.c
index 37183cfb6a..497ae475e7 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -941,8 +941,8 @@ arena_get_retry (mstate ar_ptr, size_t bytes)
   return ar_ptr;
 }
 
-static void __attribute__ ((section ("__libc_thread_freeres_fn")))
-arena_thread_freeres (void)
+void
+__malloc_arena_thread_freeres (void)
 {
   /* Shut down the thread cache first.  This could deallocate data for
      the thread arena, so do this before we put the arena on the free
@@ -966,7 +966,6 @@ arena_thread_freeres (void)
       __libc_lock_unlock (free_list_lock);
     }
 }
-text_set_element (__libc_thread_subfreeres, arena_thread_freeres);
 
 /*
  * Local variables:
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index ad054508ee..9cee0fb2d7 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -71,6 +71,9 @@ void __malloc_fork_unlock_parent (void) attribute_hidden;
 /* Called in the child process after a fork.  */
 void __malloc_fork_unlock_child (void) attribute_hidden;
 
+/* Called as part of the thread shutdown sequence.  */
+void __malloc_arena_thread_freeres (void) attribute_hidden;
+
 /* Set *RESULT to LEFT * RIGHT.  Return true if the multiplication
    overflowed.  */
 static inline bool
diff --git a/malloc/thread-freeres.c b/malloc/thread-freeres.c
index 53ce41bb78..8902c845bc 100644
--- a/malloc/thread-freeres.c
+++ b/malloc/thread-freeres.c
@@ -16,16 +16,24 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <stdlib.h>
 #include <libc-internal.h>
-#include <set-hooks.h>
+#include <malloc-internal.h>
+#include <resolv/resolv-internal.h>
+#include <rpc/rpc.h>
+#include <string.h>
 
-#ifdef _LIBC_REENTRANT
-DEFINE_HOOK (__libc_thread_subfreeres, (void));
-
-void __attribute__ ((section ("__libc_thread_freeres_fn")))
+/* Thread shutdown function.  Note that this function must be called
+   for threads during shutdown for correctness reasons.  Unlike
+   __libc_subfreeres, skipping calls to it is not a valid
+   optimization.  */
+void
 __libc_thread_freeres (void)
 {
-  RUN_HOOK (__libc_thread_subfreeres, ());
+  call_function_static_weak (__rpc_thread_destroy);
+  call_function_static_weak (__res_thread_freeres);
+  call_function_static_weak (__strerror_thread_freeres);
+
+  /* This should come last because it shuts down malloc for this
+     thread and the other shutdown functions might well call free.  */
+  call_function_static_weak (__malloc_arena_thread_freeres);
 }
-#endif
diff --git a/manual/memory.texi b/manual/memory.texi
index b95f6aa1b9..2fac64939f 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -404,7 +404,7 @@ this function is in @file{stdlib.h}.
 @c      reads&writes next_to_use and iterates over arena next without guards
 @c      those are harmless as long as we don't drop arenas from the
 @c      NEXT list, and we never do; when a thread terminates,
-@c      arena_thread_freeres prepends the arena to the free_list
+@c      __malloc_arena_thread_freeres prepends the arena to the free_list
 @c      NEXT_FREE list, but NEXT is never modified, so it's safe!
 @c     mutex_trylock (arena lock) @asulock @aculock
 @c     mutex_lock (arena lock) dup @asulock @aculock
diff --git a/resolv/res-close.c b/resolv/res-close.c
index e02f5afa15..38572b1d2f 100644
--- a/resolv/res-close.c
+++ b/resolv/res-close.c
@@ -126,8 +126,8 @@ res_nclose (res_state statp)
 libc_hidden_def (__res_nclose)
 
 /* This is called when a thread is exiting to free resources held in _res.  */
-static void __attribute__ ((section ("__libc_thread_freeres_fn")))
-res_thread_freeres (void)
+void
+__res_thread_freeres (void)
 {
   __resolv_context_freeres ();
 
@@ -140,5 +140,4 @@ res_thread_freeres (void)
   /* Make sure we do a full re-initialization the next time.  */
   _res.options = 0;
 }
-text_set_element (__libc_thread_subfreeres, res_thread_freeres);
-text_set_element (__libc_subfreeres, res_thread_freeres);
+text_set_element (__libc_subfreeres, __res_thread_freeres);
diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h
index ac6e495927..b8e447c726 100644
--- a/resolv/resolv-internal.h
+++ b/resolv/resolv-internal.h
@@ -97,4 +97,7 @@ int __res_nopt (struct resolv_context *, int n0,
 int __inet_pton_length (int af, const char *src, size_t srclen, void *);
 libc_hidden_proto (__inet_pton_length)
 
+/* Called as part of the thread shutdown sequence.  */
+void __res_thread_freeres (void) attribute_hidden;
+
 #endif  /* _RESOLV_INTERNAL_H */
diff --git a/resolv/resolv_conf.c b/resolv/resolv_conf.c
index ab4e5dc82c..08c3a9a163 100644
--- a/resolv/resolv_conf.c
+++ b/resolv/resolv_conf.c
@@ -673,7 +673,7 @@ __resolv_conf_detach (struct __res_state *resp)
 }
 
 /* Deallocate the global data.  */
-static void __attribute__ ((section ("__libc_thread_freeres_fn")))
+static void
 freeres (void)
 {
   /* No locking because this function is supposed to be called when
diff --git a/string/strerror_l.c b/string/strerror_l.c
index 7d90e809ce..2a9c3b5e0b 100644
--- a/string/strerror_l.c
+++ b/string/strerror_l.c
@@ -57,15 +57,9 @@ strerror_l (int errnum, locale_t loc)
 }
 
 
-#ifdef _LIBC
-# ifdef _LIBC_REENTRANT
-/* This is called when a thread is exiting to free the last_value string.  */
-static void __attribute__ ((section ("__libc_thread_freeres_fn")))
-strerror_thread_freeres (void)
+void
+__strerror_thread_freeres (void)
 {
   free (last_value);
 }
-text_set_element (__libc_thread_subfreeres, strerror_thread_freeres);
-text_set_element (__libc_subfreeres, strerror_thread_freeres);
-# endif
-#endif
+text_set_element (__libc_subfreeres, __strerror_thread_freeres);
diff --git a/sunrpc/rpc_thread.c b/sunrpc/rpc_thread.c
index 3b1213aca7..31ccd89f74 100644
--- a/sunrpc/rpc_thread.c
+++ b/sunrpc/rpc_thread.c
@@ -15,7 +15,7 @@ static __thread struct rpc_thread_variables *thread_rpc_vars
 /*
  * Task-variable destructor
  */
-void __attribute__ ((section ("__libc_thread_freeres_fn")))
+void
 __rpc_thread_destroy (void)
 {
 	struct rpc_thread_variables *tvp = thread_rpc_vars;
@@ -36,12 +36,8 @@ __rpc_thread_destroy (void)
 		thread_rpc_vars = NULL;
 	}
 }
-#ifdef _LIBC_REENTRANT
-text_set_element (__libc_thread_subfreeres, __rpc_thread_destroy);
-#endif
 text_set_element (__libc_subfreeres, __rpc_thread_destroy);
 
-
 /*
  * Initialize RPC multi-threaded operation
  */
diff --git a/sysdeps/mach/strerror_l.c b/sysdeps/mach/strerror_l.c
index 61515a46b8..b9842ccf40 100644
--- a/sysdeps/mach/strerror_l.c
+++ b/sysdeps/mach/strerror_l.c
@@ -87,15 +87,9 @@ strerror_l (int errnum, locale_t loc)
 }
 
 
-#ifdef _LIBC
-# ifdef _LIBC_REENTRANT
-/* This is called when a thread is exiting to free the last_value string.  */
-static void __attribute__ ((section ("__libc_thread_freeres_fn")))
-strerror_thread_freeres (void)
+void
+__strerror_thread_freeres (void)
 {
   free (last_value);
 }
-text_set_element (__libc_thread_subfreeres, strerror_thread_freeres);
-text_set_element (__libc_subfreeres, strerror_thread_freeres);
-# endif
-#endif
+text_set_element (__libc_subfreeres, __strerror_thread_freeres);