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Lock pshared_lock shared around fork, to ensure that the COW snapshot

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of the pshared hash in child is consistent and can be safely used.

Reported and tested by:	"Oleg V. Nauman" <oleg@opentransfer.com>
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Konstantin Belousov 2016-03-21 06:52:35 +00:00
parent 07f22a288d
commit 53fd961f05
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=297141
4 changed files with 22 additions and 2 deletions
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6
lib/libthr/thread/thr_fork.c
View File

@ -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();
}

2
lib/libthr/thread/thr_init.c
View File

@ -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;

2
lib/libthr/thread/thr_private.h
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@ -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

14
lib/libthr/thread/thr_pshared.c
View File

@ -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);
}