Author: davidxu
Date: Wed Sep 1 03:11:21 2010
New Revision: 212077
URL: http://svn.freebsd.org/changeset/base/212077
Log:
Change atfork lock from mutex to rwlock, also make mutexes used by malloc()
module private type, when private type mutex is locked/unlocked, thread
critical region is entered or leaved. These changes makes fork()
async-signal safe which required by POSIX. Note that user's atfork handler
still needs to be async-signal safe, but it is not problem of libthr, it
is user's responsiblity.
Modified:
head/lib/libthr/thread/thr_fork.c
head/lib/libthr/thread/thr_init.c
head/lib/libthr/thread/thr_mutex.c
head/lib/libthr/thread/thr_private.h
head/lib/libthr/thread/thr_umtx.c
head/lib/libthr/thread/thr_umtx.h
Modified: head/lib/libthr/thread/thr_fork.c
==============================================================================
--- head/lib/libthr/thread/thr_fork.c Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_fork.c Wed Sep 1 03:11:21 2010
(r212077)
@@ -89,9 +89,9 @@ _pthread_atfork(void (*prepare)(void), v
af->prepare = prepare;
af->parent = parent;
af->child = child;
- THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
+ _thr_rwl_rdlock(&_thr_atfork_lock);
TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
- THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
+ _thr_rwl_unlock(&_thr_atfork_lock);
return (0);
}
@@ -104,7 +104,7 @@ __pthread_cxa_finalize(struct dl_phdr_in
_thr_check_init();
curthread = _get_curthread();
- THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
+ _thr_rwl_wrlock(&_thr_atfork_lock);
TAILQ_FOREACH_SAFE(af, &_thr_atfork_list, qe, af1) {
if (__elf_phdr_match_addr(phdr_info, af->prepare) ||
__elf_phdr_match_addr(phdr_info, af->parent) ||
@@ -113,7 +113,7 @@ __pthread_cxa_finalize(struct dl_phdr_in
free(af);
}
}
- THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
+ _thr_rwl_unlock(&_thr_atfork_lock);
_thr_tsd_unload(phdr_info);
_thr_sigact_unload(phdr_info);
}
@@ -137,7 +137,7 @@ _fork(void)
curthread = _get_curthread();
- THR_UMUTEX_LOCK(curthread, &_thr_atfork_lock);
+ _thr_rwl_rdlock(&_thr_atfork_lock);
/* Run down atfork prepare handlers. */
TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
@@ -146,6 +146,12 @@ _fork(void)
}
/*
+ * Block all signals until we reach a safe point.
+ */
+ _thr_signal_block(curthread);
+ _thr_signal_prefork();
+
+ /*
* All bets are off as to what should happen soon if the parent
* process was not so kindly as to set up pthread fork hooks to
* relinquish all running threads.
@@ -158,12 +164,6 @@ _fork(void)
was_threaded = 0;
}
- /*
- * Block all signals until we reach a safe point.
- */
- _thr_signal_block(curthread);
- _thr_signal_prefork();
-
/* Fork a new process: */
if ((ret = __sys_fork()) == 0) {
/* Child process */
@@ -182,7 +182,7 @@ _fork(void)
/* clear other threads locked us. */
_thr_umutex_init(&curthread->lock);
- _thr_umutex_init(&_thr_atfork_lock);
+ _mutex_fork(curthread);
_thr_signal_postfork_child();
@@ -192,13 +192,12 @@ _fork(void)
/* reinitialize libc spinlocks. */
_thr_spinlock_init();
- _mutex_fork(curthread);
/* reinitalize library. */
_libpthread_init(curthread);
- /* Ready to continue, unblock signals. */
- _thr_signal_unblock(curthread);
+ /* atfork is reinitializeded by _libpthread_init()! */
+ _thr_rwl_rdlock(&_thr_atfork_lock);
if (was_threaded) {
__isthreaded = 1;
@@ -206,32 +205,36 @@ _fork(void)
__isthreaded = 0;
}
+ /* Ready to continue, unblock signals. */
+ _thr_signal_unblock(curthread);
+
/* Run down atfork child handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
if (af->child != NULL)
af->child();
}
+ _thr_rwlock_unlock(&_thr_atfork_lock);
} else {
/* Parent process */
errsave = errno;
_thr_signal_postfork();
- /* Ready to continue, unblock signals. */
- _thr_signal_unblock(curthread);
-
if (was_threaded) {
_rtld_atfork_post(rtld_locks);
_malloc_postfork();
}
+ /* Ready to continue, unblock signals. */
+ _thr_signal_unblock(curthread);
+
/* Run down atfork parent handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
if (af->parent != NULL)
af->parent();
}
- THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
+ _thr_rwlock_unlock(&_thr_atfork_lock);
}
errno = errsave;
Modified: head/lib/libthr/thread/thr_init.c
==============================================================================
--- head/lib/libthr/thread/thr_init.c Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_init.c Wed Sep 1 03:11:21 2010
(r212077)
@@ -65,7 +65,7 @@ pthreadlist _thread_list = TAILQ_HEAD_IN
pthreadlist _thread_gc_list = TAILQ_HEAD_INITIALIZER(_thread_gc_list);
int _thread_active_threads = 1;
atfork_head _thr_atfork_list = TAILQ_HEAD_INITIALIZER(_thr_atfork_list);
-struct umutex _thr_atfork_lock = DEFAULT_UMUTEX;
+struct urwlock _thr_atfork_lock = DEFAULT_URWLOCK;
struct pthread_prio _thr_priorities[3] = {
{RTP_PRIO_MIN, RTP_PRIO_MAX, 0}, /* FIFO */
@@ -427,7 +427,7 @@ init_private(void)
_thr_umutex_init(&_cond_static_lock);
_thr_umutex_init(&_rwlock_static_lock);
_thr_umutex_init(&_keytable_lock);
- _thr_umutex_init(&_thr_atfork_lock);
+ _thr_urwlock_init(&_thr_atfork_lock);
_thr_umutex_init(&_thr_event_lock);
_thr_once_init();
_thr_spinlock_init();
Modified: head/lib/libthr/thread/thr_mutex.c
==============================================================================
--- head/lib/libthr/thread/thr_mutex.c Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_mutex.c Wed Sep 1 03:11:21 2010
(r212077)
@@ -224,8 +224,12 @@ _pthread_mutex_init_calloc_cb(pthread_mu
.m_ceiling = 0
};
static const struct pthread_mutex_attr *pattr = &attr;
+ int ret;
- return mutex_init(mutex, (pthread_mutexattr_t *)&pattr, calloc_cb);
+ ret = mutex_init(mutex, (pthread_mutexattr_t *)&pattr, calloc_cb);
+ if (ret == 0)
+ (*mutex)->m_private = 1;
+ return (ret);
}
void
@@ -319,13 +323,16 @@ mutex_trylock_common(struct pthread *cur
id = TID(curthread);
m = *mutex;
+ if (m->m_private)
+ THR_CRITICAL_ENTER(curthread);
ret = _thr_umutex_trylock(&m->m_lock, id);
if (ret == 0) {
ENQUEUE_MUTEX(curthread, m);
} else if (m->m_owner == curthread) {
ret = mutex_self_trylock(m);
} /* else {} */
-
+ if (ret && m->m_private)
+ THR_CRITICAL_LEAVE(curthread);
return (ret);
}
@@ -417,13 +424,19 @@ static inline int
mutex_lock_common(struct pthread *curthread, struct pthread_mutex *m,
const struct timespec *abstime)
{
+ int ret;
+ if (m->m_private)
+ THR_CRITICAL_ENTER(curthread);
if (_thr_umutex_trylock2(&m->m_lock, TID(curthread)) == 0) {
ENQUEUE_MUTEX(curthread, m);
- return (0);
+ ret = 0;
+ } else {
+ ret = mutex_lock_sleep(curthread, m, abstime);
}
-
- return (mutex_lock_sleep(curthread, m, abstime));
+ if (ret && m->m_private)
+ THR_CRITICAL_LEAVE(curthread);
+ return (ret);
}
int
@@ -625,6 +638,8 @@ mutex_unlock_common(pthread_mutex_t *mut
MUTEX_INIT_LINK(m);
_thr_umutex_unlock(&m->m_lock, id);
}
+ if (m->m_private)
+ THR_CRITICAL_LEAVE(curthread);
return (0);
}
@@ -660,6 +675,9 @@ _mutex_cv_unlock(pthread_mutex_t *mutex,
}
MUTEX_INIT_LINK(m);
_thr_umutex_unlock(&m->m_lock, TID(curthread));
+
+ if (m->m_private)
+ THR_CRITICAL_LEAVE(curthread);
return (0);
}
Modified: head/lib/libthr/thread/thr_private.h
==============================================================================
--- head/lib/libthr/thread/thr_private.h Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_private.h Wed Sep 1 03:11:21 2010
(r212077)
@@ -132,6 +132,7 @@ struct pthread_mutex {
int m_refcount;
int m_spinloops;
int m_yieldloops;
+ int m_private;
/*
* Link for all mutexes a thread currently owns.
*/
@@ -587,7 +588,7 @@ extern pthreadlist _thread_gc_list __hid
extern int _thread_active_threads;
extern atfork_head _thr_atfork_list __hidden;
-extern struct umutex _thr_atfork_lock __hidden;
+extern struct urwlock _thr_atfork_lock __hidden;
/* Default thread attributes: */
extern struct pthread_attr _pthread_attr_default __hidden;
Modified: head/lib/libthr/thread/thr_umtx.c
==============================================================================
--- head/lib/libthr/thread/thr_umtx.c Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_umtx.c Wed Sep 1 03:11:21 2010
(r212077)
@@ -47,6 +47,13 @@ _thr_umutex_init(struct umutex *mtx)
*mtx = default_mtx;
}
+void
+_thr_urwlock_init(struct urwlock *rwl)
+{
+ static struct urwlock default_rwl = DEFAULT_URWLOCK;
+ *rwl = default_rwl;
+}
+
int
__thr_umutex_lock(struct umutex *mtx, uint32_t id)
{
Modified: head/lib/libthr/thread/thr_umtx.h
==============================================================================
--- head/lib/libthr/thread/thr_umtx.h Wed Sep 1 02:18:33 2010
(r212076)
+++ head/lib/libthr/thread/thr_umtx.h Wed Sep 1 03:11:21 2010
(r212077)
@@ -32,7 +32,8 @@
#include <strings.h>
#include <sys/umtx.h>
-#define DEFAULT_UMUTEX {0,0, {0,0},{0,0,0,0}}
+#define DEFAULT_UMUTEX {0,0,{0,0},{0,0,0,0}}
+#define DEFAULT_URWLOCK {0,0,0,0,{0,0,0,0}}
int __thr_umutex_lock(struct umutex *mtx, uint32_t id) __hidden;
int __thr_umutex_timedlock(struct umutex *mtx, uint32_t id,
@@ -43,6 +44,8 @@ int __thr_umutex_set_ceiling(struct umut
uint32_t *oldceiling) __hidden;
void _thr_umutex_init(struct umutex *mtx) __hidden;
+void _thr_urwlock_init(struct urwlock *rwl) __hidden;
+
int _thr_umtx_wait(volatile long *mtx, long exp,
const struct timespec *timeout) __hidden;
int _thr_umtx_wait_uint(volatile u_int *mtx, u_int exp,
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