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| author | Torvald Riegel <triegel@redhat.com> | 2016-08-17 13:56:11 +0200 |
|---|---|---|
| committer | Torvald Riegel <triegel@redhat.com> | 2016-08-18 20:53:37 +0200 |
| commit | 6f9d4f595e4073807ad0e844cbb3b3d7158b76d5 (patch) | |
| tree | d0064a3e11f1326fcdfcad1b239076044da9a762 /resolv/res_hconf.c | |
| parent | b65f0b7b2ecd144800830633a4c2719f11775572 (diff) | |
| download | glibc-6f9d4f595e4073807ad0e844cbb3b3d7158b76d5.zip glibc-6f9d4f595e4073807ad0e844cbb3b3d7158b76d5.tar.gz glibc-6f9d4f595e4073807ad0e844cbb3b3d7158b76d5.tar.bz2 | |
Fix incorrect double-checked locking related to _res_hconf.initialized.
_res_hconf.initialized was not suitable for use in a multi-threaded
environment due to the lack of atomics and memory barriers. Use of it was
also unnecessary because _res_hconf_init did the right thing by using
__libc_once. This patch fixes the glibc-internal uses by just calling
_res_hconf_init unconditionally, and switches to a release MO atomic store
for _res_hconf.initialized to fix the glibc side of the synchronization
problem (which will maintain backward compatibility, but cannot fix the
lack of acquire MO on any glibc-external loads).
[BZ #20477]
* resolv/res_hconf.c (do_init): Use atomic access.
* resolv/res_hconf.h: Add comments.
* nscd/aicache.c (addhstaiX): Call _res_hconf_init unconditionally.
* nss/getXXbyYY_r.c (REENTRANT_NAME): Likewise.
* sysdeps/posix/getaddrinfo.c (gaih_inet): Likewise.
Diffstat (limited to 'resolv/res_hconf.c')
| -rw-r--r-- | resolv/res_hconf.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/resolv/res_hconf.c b/resolv/res_hconf.c index 5cd1289..093c268 100644 --- a/resolv/res_hconf.c +++ b/resolv/res_hconf.c @@ -348,7 +348,8 @@ do_init (void) arg_trimdomain_list (ENV_TRIM_OVERR, 1, envval); } - _res_hconf.initialized = 1; + /* See comments on the declaration of _res_hconf. */ + atomic_store_release (&_res_hconf.initialized, 1); } |