Author: kib
Date: Thu Nov 27 11:27:59 2008
New Revision: 185369
URL: http://svn.freebsd.org/changeset/base/185369
Log:
Add two rtld exported symbols, _rtld_atfork_pre and _rtld_atfork_post.
Threading library calls _pre before the fork, allowing the rtld to
lock itself to ensure that other threads of the process are out of
dynamic linker. _post releases the locks.
This allows the rtld to have consistent state in the child. Although
child may legitimately call only async-safe functions, the call may
need plt relocation resolution, and this requires working rtld.
Reported and debugging help by: rink
Reviewed by: kan, davidxu
MFC after: 1 month (anyway, not before 7.1 is out)
Modified:
head/lib/libc/gen/Symbol.map
head/lib/libc/gen/dlfcn.c
head/lib/libthr/thread/thr_fork.c
head/libexec/rtld-elf/Symbol.map
head/libexec/rtld-elf/rtld.c
head/libexec/rtld-elf/rtld_lock.c
head/libexec/rtld-elf/rtld_lock.h
Modified: head/lib/libc/gen/Symbol.map
==============================================================================
--- head/lib/libc/gen/Symbol.map Thu Nov 27 11:25:21 2008
(r185368)
+++ head/lib/libc/gen/Symbol.map Thu Nov 27 11:27:59 2008
(r185369)
@@ -432,6 +432,8 @@ FBSDprivate_1.0 {
_spinlock;
_spinlock_debug;
_spinunlock;
+ _rtld_atfork_pre;
+ _rtld_atfork_post;
_rtld_error; /* for private use */
_rtld_thread_init; /* for private use */
_err;
Modified: head/lib/libc/gen/dlfcn.c
==============================================================================
--- head/lib/libc/gen/dlfcn.c Thu Nov 27 11:25:21 2008 (r185368)
+++ head/lib/libc/gen/dlfcn.c Thu Nov 27 11:27:59 2008 (r185369)
@@ -137,3 +137,15 @@ dl_iterate_phdr(int (*callback)(struct d
_rtld_error(sorry);
return 0;
}
+
+#pragma weak _rtld_atfork_pre
+void
+_rtld_atfork_pre(int *locks)
+{
+}
+
+#pragma weak _rtld_atfork_post
+void
+_rtld_atfork_post(int *locks)
+{
+}
Modified: head/lib/libthr/thread/thr_fork.c
==============================================================================
--- head/lib/libthr/thread/thr_fork.c Thu Nov 27 11:25:21 2008
(r185368)
+++ head/lib/libthr/thread/thr_fork.c Thu Nov 27 11:27:59 2008
(r185369)
@@ -67,6 +67,7 @@
#include "un-namespace.h"
#include "libc_private.h"
+#include "rtld_lock.h"
#include "thr_private.h"
__weak_reference(_pthread_atfork, pthread_atfork);
@@ -105,6 +106,7 @@ _fork(void)
pid_t ret;
int errsave;
int unlock_malloc;
+ int rtld_locks[16];
if (!_thr_is_inited())
return (__sys_fork());
@@ -127,6 +129,7 @@ _fork(void)
if (_thr_isthreaded() != 0) {
unlock_malloc = 1;
_malloc_prefork();
+ _rtld_atfork_pre(rtld_locks);
} else {
unlock_malloc = 0;
}
@@ -167,6 +170,10 @@ _fork(void)
/* Ready to continue, unblock signals. */
_thr_signal_unblock(curthread);
+ if (unlock_malloc) {
+ _rtld_atfork_post(rtld_locks);
+ }
+
/* Run down atfork child handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
if (af->child != NULL)
@@ -179,8 +186,10 @@ _fork(void)
/* Ready to continue, unblock signals. */
_thr_signal_unblock(curthread);
- if (unlock_malloc)
+ if (unlock_malloc) {
+ _rtld_atfork_post(rtld_locks);
_malloc_postfork();
+ }
/* Run down atfork parent handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
Modified: head/libexec/rtld-elf/Symbol.map
==============================================================================
--- head/libexec/rtld-elf/Symbol.map Thu Nov 27 11:25:21 2008
(r185368)
+++ head/libexec/rtld-elf/Symbol.map Thu Nov 27 11:27:59 2008
(r185369)
@@ -21,4 +21,6 @@ FBSDprivate_1.0 {
_rtld_thread_init;
_rtld_allocate_tls;
_rtld_free_tls;
+ _rtld_atfork_pre;
+ _rtld_atfork_post;
};
Modified: head/libexec/rtld-elf/rtld.c
==============================================================================
--- head/libexec/rtld-elf/rtld.c Thu Nov 27 11:25:21 2008
(r185368)
+++ head/libexec/rtld-elf/rtld.c Thu Nov 27 11:27:59 2008
(r185369)
@@ -206,6 +206,8 @@ static func_ptr_type exports[] = {
(func_ptr_type) &_rtld_allocate_tls,
(func_ptr_type) &_rtld_free_tls,
(func_ptr_type) &dl_iterate_phdr,
+ (func_ptr_type) &_rtld_atfork_pre,
+ (func_ptr_type) &_rtld_atfork_post,
NULL
};
Modified: head/libexec/rtld-elf/rtld_lock.c
==============================================================================
--- head/libexec/rtld-elf/rtld_lock.c Thu Nov 27 11:25:21 2008
(r185368)
+++ head/libexec/rtld-elf/rtld_lock.c Thu Nov 27 11:27:59 2008
(r185369)
@@ -316,3 +316,19 @@ _rtld_thread_init(struct RtldLockInfo *p
thread_mask_set(flags);
dbg("_rtld_thread_init: done");
}
+
+void
+_rtld_atfork_pre(int *locks)
+{
+
+ locks[2] = wlock_acquire(rtld_phdr_lock);
+ locks[0] = rlock_acquire(rtld_bind_lock);
+}
+
+void
+_rtld_atfork_post(int *locks)
+{
+
+ rlock_release(rtld_bind_lock, locks[0]);
+ wlock_release(rtld_phdr_lock, locks[2]);
+}
Modified: head/libexec/rtld-elf/rtld_lock.h
==============================================================================
--- head/libexec/rtld-elf/rtld_lock.h Thu Nov 27 11:25:21 2008
(r185368)
+++ head/libexec/rtld-elf/rtld_lock.h Thu Nov 27 11:27:59 2008
(r185369)
@@ -44,6 +44,8 @@ struct RtldLockInfo
};
extern void _rtld_thread_init(struct RtldLockInfo *);
+extern void _rtld_atfork_pre(int *);
+extern void _rtld_atfork_post(int *);
#ifdef IN_RTLD
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
