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| author | Ulrich Drepper <drepper@redhat.com> | 2009-12-15 12:32:27 -0800 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 2009-12-15 12:32:27 -0800 |
| commit | 2af6396817fb9df98e63de75dd59fd999ee9f1d0 (patch) | |
| tree | d66827c66d770f1f3d697dbb027b59064e6ab0e0 /elf/dl-object.c | |
| parent | 2510d01ddba195f8cfaa3c2349f75e0612719d82 (diff) | |
| download | glibc-2af6396817fb9df98e63de75dd59fd999ee9f1d0.tar.gz glibc-2af6396817fb9df98e63de75dd59fd999ee9f1d0.tar.xz glibc-2af6396817fb9df98e63de75dd59fd999ee9f1d0.zip | |
Avoid ELF lookup race.
On some architectures the update of the l_used field in the lookup functions races with setting the other bits in the bitfield. Simply avoid this and optimize use of l_used in general.
Diffstat (limited to 'elf/dl-object.c')
| -rw-r--r-- | elf/dl-object.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/elf/dl-object.c b/elf/dl-object.c index be4ea38f9f..788e2c07b9 100644 --- a/elf/dl-object.c +++ b/elf/dl-object.c @@ -1,5 +1,5 @@ /* Storage management for the chain of loaded shared objects. - Copyright (C) 1995-2002,2004,2006,2007,2008 Free Software Foundation, Inc. + Copyright (C) 1995-2002,2004,2006-2008,2009 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 @@ -67,6 +67,10 @@ _dl_new_object (char *realname, const char *libname, int type, new->l_name = realname; new->l_type = type; + /* If we set the bit now since we know it is never used we avoid + dirtying the cache line later. */ + if ((GLRO(dl_debug_mask) & DL_DEBUG_UNUSED) == 0) + new->l_used = 1; new->l_loader = loader; #if NO_TLS_OFFSET != 0 new->l_tls_offset = NO_TLS_OFFSET; @@ -174,7 +178,7 @@ _dl_new_object (char *realname, const char *libname, int type, if (result == NULL) { /* We were not able to determine the current directory. - Note that free(origin) is OK if origin == NULL. */ + Note that free(origin) is OK if origin == NULL. */ free (origin); origin = (char *) -1; goto out; |