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authorTorvald Riegel <triegel@redhat.com>2016-08-17 13:56:11 +0200
committerTorvald Riegel <triegel@redhat.com>2016-08-18 20:53:37 +0200
commit6f9d4f595e4073807ad0e844cbb3b3d7158b76d5 (patch)
treed0064a3e11f1326fcdfcad1b239076044da9a762 /nscd
parentb65f0b7b2ecd144800830633a4c2719f11775572 (diff)
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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 'nscd')
-rw-r--r--nscd/aicache.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/nscd/aicache.c b/nscd/aicache.c
index a2e6cf8475..32c8f57b41 100644
--- a/nscd/aicache.c
+++ b/nscd/aicache.c
@@ -101,8 +101,7 @@ addhstaiX (struct database_dyn *db, int fd, request_header *req,
   nip = hosts_database;
 
   /* Initialize configurations.  */
-  if (__glibc_unlikely (!_res_hconf.initialized))
-    _res_hconf_init ();
+  _res_hconf_init ();
   if (__res_maybe_init (&_res, 0) == -1)
     no_more = 1;