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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.
This commit is contained in:
Ulrich Drepper 2007-01-15 20:48:56 +00:00
parent fb453d084d
commit 4e35ef2c71
5 changed files with 68 additions and 27 deletions
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14
ChangeLog
View File

@ -1,3 +1,17 @@
2007-01-15 Ulrich Drepper <drepper@redhat.com>
* 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.
2007-01-13 Ulrich Drepper <drepper@redhat.com> 2007-01-13 Ulrich Drepper <drepper@redhat.com>
* inet/Makefile: Define CFLAGS-getsrvbynm_r.c and * inet/Makefile: Define CFLAGS-getsrvbynm_r.c and

33
elf/dl-lookup.c
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@ -1,5 +1,5 @@
/* Look up a symbol in the loaded objects. /* 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. This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or The GNU C Library is free software; you can redistribute it and/or
@ -25,6 +25,7 @@
#include <ldsodefs.h> #include <ldsodefs.h>
#include <dl-hash.h> #include <dl-hash.h>
#include <dl-machine.h> #include <dl-machine.h>
#include <sysdep-cancel.h>
#include <bits/libc-lock.h> #include <bits/libc-lock.h>
#include <tls.h> #include <tls.h>
@ -85,7 +86,7 @@ dl_new_hash (const char *s)
/* Add extra dependency on MAP to UNDEF_MAP. */ /* Add extra dependency on MAP to UNDEF_MAP. */
static int static int
internal_function 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 **list;
struct link_map *runp; struct link_map *runp;
@ -98,8 +99,18 @@ add_dependency (struct link_map *undef_map, struct link_map *map)
if (undef_map == map) if (undef_map == map)
return 0; return 0;
/* Make sure nobody can unload the object while we are at it. */ /* Make sure nobody can unload the object while we are at it.
__rtld_lock_lock_recursive (GL(dl_load_lock)); 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. */ /* Avoid references to objects which cannot be unloaded anyway. */
if (map->l_type != lt_loaded 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 (); bump_num_relocations ();
/* No other flag than DL_LOOKUP_ADD_DEPENDENCY is allowed if we look /* No other flag than DL_LOOKUP_ADD_DEPENDENCY and DL_LOOKUP_SCOPE_LOCK
up a versioned symbol. */ is allowed if we look up a versioned symbol. */
assert (version == NULL || flags == 0 || flags == DL_LOOKUP_ADD_DEPENDENCY); assert (version == NULL || (flags & ~(DL_LOOKUP_ADD_DEPENDENCY
| DL_LOOKUP_SCOPE_LOCK)) == 0);
size_t i = 0; size_t i = 0;
if (__builtin_expect (skip_map != NULL, 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. */ runtime lookups. */
&& (flags & DL_LOOKUP_ADD_DEPENDENCY) != 0 && (flags & DL_LOOKUP_ADD_DEPENDENCY) != 0
/* Add UNDEF_MAP to the dependencies. */ /* 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 /* Something went wrong. Perhaps the object we tried to reference
was just removed. Try finding another definition. */ was just removed. Try finding another definition. */
return _dl_lookup_symbol_x (undef_name, undef_map, ref, return _dl_lookup_symbol_x (undef_name, undef_map, ref,
symbol_scope, version, type_class, (flags & DL_LOOKUP_SCOPE_LOCK) == 0
flags, skip_map); ? symbol_scope : undef_map->l_scope, version,
type_class, flags, skip_map);
/* The object is used. */ /* The object is used. */
current_value.m->l_used = 1; current_value.m->l_used = 1;

36
elf/dl-runtime.c
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@ -1,5 +1,5 @@
/* On-demand PLT fixup for shared objects. /* 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. This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or The GNU C Library is free software; you can redistribute it and/or
@ -93,14 +93,20 @@ _dl_fixup (
version = NULL; 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) 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, result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope,
l->l_scope, version, ELF_RTYPE_CLASS_PLT, version, ELF_RTYPE_CLASS_PLT, flags, NULL);
DL_LOOKUP_ADD_DEPENDENCY, 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); __rtld_mrlock_unlock (l->l_scope_lock);
/* Currently result contains the base load address (or link map) /* Currently result contains the base load address (or link map)
@ -181,15 +187,21 @@ _dl_profile_fixup (
version = NULL; 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) 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, result = _dl_lookup_symbol_x (strtab + refsym->st_name, l,
l->l_scope, version, &defsym, l->l_scope, version,
ELF_RTYPE_CLASS_PLT, ELF_RTYPE_CLASS_PLT, flags, NULL);
DL_LOOKUP_ADD_DEPENDENCY, 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); __rtld_mrlock_unlock (l->l_scope_lock);
/* Currently result contains the base load address (or link map) /* Currently result contains the base load address (or link map)

4
elf/dl-sym.c
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@ -1,5 +1,5 @@
/* Look up a symbol in a shared object loaded by `dlopen'. /* 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. This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or 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.name = name;
args.map = match; args.map = match;
args.vers = vers; args.vers = vers;
args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY; args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_SCOPE_LOCK;
args.refp = &ref; args.refp = &ref;
const char *objname; const char *objname;

8
sysdeps/generic/ldsodefs.h
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@ -1,5 +1,5 @@
/* Run-time dynamic linker data structures for loaded ELF shared objects. /* Run-time dynamic linker data structures for loaded ELF shared objects.
Copyright (C) 1995-2003, 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. This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or The GNU C Library is free software; you can redistribute it and/or
@ -838,7 +838,9 @@ enum
DL_LOOKUP_ADD_DEPENDENCY = 1, DL_LOOKUP_ADD_DEPENDENCY = 1,
/* Return most recent version instead of default version for /* Return most recent version instead of default version for
unversioned lookup. */ unversioned lookup. */
DL_LOOKUP_RETURN_NEWEST = 2 DL_LOOKUP_RETURN_NEWEST = 2,
/* Set if the scopr lock in the UNDEF_MAP is taken. */
DL_LOOKUP_SCOPE_LOCK = 4
}; };
/* Lookup versioned symbol. */ /* Lookup versioned symbol. */
@ -847,7 +849,7 @@ extern lookup_t _dl_lookup_symbol_x (const char *undef,
const ElfW(Sym) **sym, const ElfW(Sym) **sym,
struct r_scope_elem *symbol_scope[], struct r_scope_elem *symbol_scope[],
const struct r_found_version *version, const struct r_found_version *version,
int type_class, int explicit, int type_class, int flags,
struct link_map *skip_map) struct link_map *skip_map)
internal_function attribute_hidden; internal_function attribute_hidden;