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authorUlrich Drepper <drepper@redhat.com>2007-01-15 20:48:56 +0000
committerUlrich Drepper <drepper@redhat.com>2007-01-15 20:48:56 +0000
commit4e35ef2c710dfefe96a491d133b5a53414e9a5c2 (patch)
treed9219ecd731de733953c1224356ecbe068b35e7f /elf
parentfb453d084d86f22718b60422a135f7c70e47f0ac (diff)
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* sysdeps/generic/ldsodefs.h: Define DL_LOOKUP_SCOPE_LOCK.
* elf/dl-lookup.c (add_dependency): If scope map is locked, unlock it before getting dl_load_lock and then relock. (_dl_lookup_symbol_x): Pass flags to add_dependency. When rerunning _dl_lookup_symbol_x, compute symbol_scope again in case we unlocked the scope. * elf/dl-runtime.c (_dl_fixup): Pass DL_LOOKUP_SCOPE_LOCK to _dl_lookup_symbol_x in case we locked the scope. (_dl_profile_fixup): Likewise. * elf/dl-sym.c (do_sym): In flags passed to call_dl_lookup, also set DL_LOOKUP_SCOPE_LOCK.
Diffstat (limited to 'elf')
-rw-r--r--elf/dl-lookup.c33
-rw-r--r--elf/dl-runtime.c36
-rw-r--r--elf/dl-sym.c4
3 files changed, 49 insertions, 24 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 019278c..a6a9584 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -1,5 +1,5 @@
/* Look up a symbol in the loaded objects.
- Copyright (C) 1995-2005, 2006 Free Software Foundation, Inc.
+ Copyright (C) 1995-2005, 2006, 2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -25,6 +25,7 @@
#include <ldsodefs.h>
#include <dl-hash.h>
#include <dl-machine.h>
+#include <sysdep-cancel.h>
#include <bits/libc-lock.h>
#include <tls.h>
@@ -85,7 +86,7 @@ dl_new_hash (const char *s)
/* Add extra dependency on MAP to UNDEF_MAP. */
static int
internal_function
-add_dependency (struct link_map *undef_map, struct link_map *map)
+add_dependency (struct link_map *undef_map, struct link_map *map, int flags)
{
struct link_map **list;
struct link_map *runp;
@@ -98,8 +99,18 @@ add_dependency (struct link_map *undef_map, struct link_map *map)
if (undef_map == map)
return 0;
- /* Make sure nobody can unload the object while we are at it. */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
+ /* Make sure nobody can unload the object while we are at it.
+ If we hold a scope lock drop it now to avoid ABBA locking problems. */
+ if ((flags & DL_LOOKUP_SCOPE_LOCK) != 0 && !RTLD_SINGLE_THREAD_P)
+ {
+ __rtld_mrlock_unlock (undef_map->l_scope_lock);
+
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
+
+ __rtld_mrlock_lock (undef_map->l_scope_lock);
+ }
+ else
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
/* Avoid references to objects which cannot be unloaded anyway. */
if (map->l_type != lt_loaded
@@ -226,9 +237,10 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
bump_num_relocations ();
- /* No other flag than DL_LOOKUP_ADD_DEPENDENCY is allowed if we look
- up a versioned symbol. */
- assert (version == NULL || flags == 0 || flags == DL_LOOKUP_ADD_DEPENDENCY);
+ /* No other flag than DL_LOOKUP_ADD_DEPENDENCY and DL_LOOKUP_SCOPE_LOCK
+ is allowed if we look up a versioned symbol. */
+ assert (version == NULL || (flags & ~(DL_LOOKUP_ADD_DEPENDENCY
+ | DL_LOOKUP_SCOPE_LOCK)) == 0);
size_t i = 0;
if (__builtin_expect (skip_map != NULL, 0))
@@ -338,12 +350,13 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
runtime lookups. */
&& (flags & DL_LOOKUP_ADD_DEPENDENCY) != 0
/* Add UNDEF_MAP to the dependencies. */
- && add_dependency (undef_map, current_value.m) < 0)
+ && add_dependency (undef_map, current_value.m, flags) < 0)
/* Something went wrong. Perhaps the object we tried to reference
was just removed. Try finding another definition. */
return _dl_lookup_symbol_x (undef_name, undef_map, ref,
- symbol_scope, version, type_class,
- flags, skip_map);
+ (flags & DL_LOOKUP_SCOPE_LOCK) == 0
+ ? symbol_scope : undef_map->l_scope, version,
+ type_class, flags, skip_map);
/* The object is used. */
current_value.m->l_used = 1;
diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c
index afc99f6..9ecf62b 100644
--- a/elf/dl-runtime.c
+++ b/elf/dl-runtime.c
@@ -1,5 +1,5 @@
/* On-demand PLT fixup for shared objects.
- Copyright (C) 1995-2002,2003,2004,2005,2006 Free Software Foundation, Inc.
+ Copyright (C) 1995-2006, 2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -93,14 +93,20 @@ _dl_fixup (
version = NULL;
}
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
if (l->l_type == lt_loaded && !RTLD_SINGLE_THREAD_P)
- __rtld_mrlock_lock (l->l_scope_lock);
+ {
+ __rtld_mrlock_lock (l->l_scope_lock);
+ flags |= DL_LOOKUP_SCOPE_LOCK;
+ }
- result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
- l->l_scope, version, ELF_RTYPE_CLASS_PLT,
- DL_LOOKUP_ADD_DEPENDENCY, NULL);
+ result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope,
+ version, ELF_RTYPE_CLASS_PLT, flags, NULL);
- if (l->l_type == lt_loaded && !RTLD_SINGLE_THREAD_P)
+ if ((flags & DL_LOOKUP_SCOPE_LOCK) != 0)
__rtld_mrlock_unlock (l->l_scope_lock);
/* Currently result contains the base load address (or link map)
@@ -181,15 +187,21 @@ _dl_profile_fixup (
version = NULL;
}
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
if (l->l_type == lt_loaded && !RTLD_SINGLE_THREAD_P)
- __rtld_mrlock_lock (l->l_scope_lock);
+ {
+ __rtld_mrlock_lock (l->l_scope_lock);
+ flags |= DL_LOOKUP_SCOPE_LOCK;
+ }
- result = _dl_lookup_symbol_x (strtab + refsym->st_name, l, &defsym,
- l->l_scope, version,
- ELF_RTYPE_CLASS_PLT,
- DL_LOOKUP_ADD_DEPENDENCY, NULL);
+ result = _dl_lookup_symbol_x (strtab + refsym->st_name, l,
+ &defsym, l->l_scope, version,
+ ELF_RTYPE_CLASS_PLT, flags, NULL);
- if (l->l_type == lt_loaded && !RTLD_SINGLE_THREAD_P)
+ if ((flags & DL_LOOKUP_SCOPE_LOCK) != 0)
__rtld_mrlock_unlock (l->l_scope_lock);
/* Currently result contains the base load address (or link map)
diff --git a/elf/dl-sym.c b/elf/dl-sym.c
index 88a5adb..1c3ab5c 100644
--- a/elf/dl-sym.c
+++ b/elf/dl-sym.c
@@ -1,5 +1,5 @@
/* Look up a symbol in a shared object loaded by `dlopen'.
- Copyright (C) 1999,2000,2001,2002,2004,2006 Free Software Foundation, Inc.
+ Copyright (C) 1999-2002,2004,2006,2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -126,7 +126,7 @@ do_sym (void *handle, const char *name, void *who,
args.name = name;
args.map = match;
args.vers = vers;
- args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY;
+ args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_SCOPE_LOCK;
args.refp = &ref;
const char *objname;