Author: kib
Date: Mon Mar 21 06:52:35 2016
New Revision: 297141
URL: https://svnweb.freebsd.org/changeset/base/297141
Log:
Lock pshared_lock shared around fork, to ensure that the COW snapshot
of the pshared hash in child is consistent and can be safely used.
Reported and tested by: "Oleg V. Nauman" <o...@opentransfer.com>
Sponsored by: The FreeBSD Foundation
Modified:
head/lib/libthr/thread/thr_fork.c
head/lib/libthr/thread/thr_init.c
head/lib/libthr/thread/thr_private.h
head/lib/libthr/thread/thr_pshared.c
Modified: head/lib/libthr/thread/thr_fork.c
==============================================================================
--- head/lib/libthr/thread/thr_fork.c Mon Mar 21 06:48:11 2016
(r297140)
+++ head/lib/libthr/thread/thr_fork.c Mon Mar 21 06:52:35 2016
(r297141)
@@ -168,6 +168,7 @@ __thr_fork(void)
if (_thr_isthreaded() != 0) {
was_threaded = 1;
_malloc_prefork();
+ __thr_pshared_atfork_pre();
_rtld_atfork_pre(rtld_locks);
} else {
was_threaded = 0;
@@ -202,8 +203,10 @@ __thr_fork(void)
_thr_signal_postfork_child();
- if (was_threaded)
+ if (was_threaded) {
_rtld_atfork_post(rtld_locks);
+ __thr_pshared_atfork_post();
+ }
_thr_setthreaded(0);
/* reinitalize library. */
@@ -236,6 +239,7 @@ __thr_fork(void)
if (was_threaded) {
_rtld_atfork_post(rtld_locks);
+ __thr_pshared_atfork_post();
_malloc_postfork();
}
Modified: head/lib/libthr/thread/thr_init.c
==============================================================================
--- head/lib/libthr/thread/thr_init.c Mon Mar 21 06:48:11 2016
(r297140)
+++ head/lib/libthr/thread/thr_init.c Mon Mar 21 06:52:35 2016
(r297141)
@@ -445,7 +445,6 @@ init_private(void)
_thr_once_init();
_thr_spinlock_init();
_thr_list_init();
- __thr_pshared_init();
_thr_wake_addr_init();
_sleepq_init();
_single_thread = NULL;
@@ -456,6 +455,7 @@ init_private(void)
* e.g. after a fork().
*/
if (init_once == 0) {
+ __thr_pshared_init();
/* Find the stack top */
mib[0] = CTL_KERN;
mib[1] = KERN_USRSTACK;
Modified: head/lib/libthr/thread/thr_private.h
==============================================================================
--- head/lib/libthr/thread/thr_private.h Mon Mar 21 06:48:11 2016
(r297140)
+++ head/lib/libthr/thread/thr_private.h Mon Mar 21 06:52:35 2016
(r297141)
@@ -952,6 +952,8 @@ void _tcb_dtor(struct tcb *);
void __thr_pshared_init(void) __hidden;
void *__thr_pshared_offpage(void *key, int doalloc) __hidden;
void __thr_pshared_destroy(void *key) __hidden;
+void __thr_pshared_atfork_pre(void) __hidden;
+void __thr_pshared_atfork_post(void) __hidden;
__END_DECLS
Modified: head/lib/libthr/thread/thr_pshared.c
==============================================================================
--- head/lib/libthr/thread/thr_pshared.c Mon Mar 21 06:48:11 2016
(r297140)
+++ head/lib/libthr/thread/thr_pshared.c Mon Mar 21 06:52:35 2016
(r297141)
@@ -252,3 +252,17 @@ __thr_pshared_destroy(void *key)
pshared_clean(key, val);
pshared_gc(curthread);
}
+
+void
+__thr_pshared_atfork_pre(void)
+{
+
+ _thr_rwl_rdlock(&pshared_lock);
+}
+
+void
+__thr_pshared_atfork_post(void)
+{
+
+ _thr_rwl_unlock(&pshared_lock);
+}
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