svn commit: r212076 - head/lib/libthr/thread
David Xu
davidxu at FreeBSD.org
Wed Sep 1 02:18:33 UTC 2010
Author: davidxu
Date: Wed Sep 1 02:18:33 2010
New Revision: 212076
URL: http://svn.freebsd.org/changeset/base/212076
Log:
Add signal handler wrapper, the reason to add it becauses there are
some cases we want to improve:
1) if a thread signal got a signal while in cancellation point,
it is possible the TDP_WAKEUP may be eaten by signal handler
if the handler called some interruptibly system calls.
2) In signal handler, we want to disable cancellation.
3) When thread holding some low level locks, it is better to
disable signal, those code need not to worry reentrancy,
sigprocmask system call is avoided because it is a bit expensive.
The signal handler wrapper works in this way:
1) libthr installs its signal handler if user code invokes sigaction
to install its handler, the user handler is recorded in internal
array.
2) when a signal is delivered, libthr's signal handler is invoke,
libthr checks if thread holds some low level lock or is in critical
region, if it is true, the signal is buffered, and all signals are
masked, once the thread leaves critical region, correct signal
mask is restored and buffered signal is processed.
3) before user signal handler is invoked, cancellation is temporarily
disabled, after user signal handler is returned, cancellation state
is restored, and pending cancellation is rescheduled.
Modified:
head/lib/libthr/thread/thr_cancel.c
head/lib/libthr/thread/thr_cond.c
head/lib/libthr/thread/thr_create.c
head/lib/libthr/thread/thr_exit.c
head/lib/libthr/thread/thr_fork.c
head/lib/libthr/thread/thr_init.c
head/lib/libthr/thread/thr_join.c
head/lib/libthr/thread/thr_kern.c
head/lib/libthr/thread/thr_private.h
head/lib/libthr/thread/thr_rtld.c
head/lib/libthr/thread/thr_sig.c
head/lib/libthr/thread/thr_syscalls.c
head/lib/libthr/thread/thr_umtx.c
head/lib/libthr/thread/thr_umtx.h
Modified: head/lib/libthr/thread/thr_cancel.c
==============================================================================
--- head/lib/libthr/thread/thr_cancel.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_cancel.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -85,14 +85,11 @@ _pthread_setcancelstate(int state, int *
oldval = curthread->cancel_enable;
switch (state) {
case PTHREAD_CANCEL_DISABLE:
- THR_LOCK(curthread);
curthread->cancel_enable = 0;
- THR_UNLOCK(curthread);
break;
case PTHREAD_CANCEL_ENABLE:
- THR_LOCK(curthread);
curthread->cancel_enable = 1;
- THR_UNLOCK(curthread);
+ testcancel(curthread);
break;
default:
return (EINVAL);
@@ -136,23 +133,22 @@ _pthread_testcancel(void)
{
struct pthread *curthread = _get_curthread();
- _thr_cancel_enter(curthread);
- _thr_cancel_leave(curthread);
+ curthread->cancel_point = 1;
+ testcancel(curthread);
+ curthread->cancel_point = 0;
}
void
_thr_cancel_enter(struct pthread *curthread)
{
- curthread->cancel_point++;
- if (curthread->cancel_enable)
- testcancel(curthread);
+ curthread->cancel_point = 1;
+ testcancel(curthread);
}
void
-_thr_cancel_enter_defer(struct pthread *curthread, int maycancel)
+_thr_cancel_enter2(struct pthread *curthread, int maycancel)
{
- curthread->cancel_defer++;
- curthread->cancel_point++;
+ curthread->cancel_point = 1;
if (__predict_false(SHOULD_CANCEL(curthread) &&
!THR_IN_CRITICAL(curthread))) {
if (!maycancel)
@@ -163,24 +159,9 @@ _thr_cancel_enter_defer(struct pthread *
}
void
-_thr_cancel_leave(struct pthread *curthread)
-{
- curthread->cancel_point--;
-}
-
-void
-_thr_cancel_leave2(struct pthread *curthread, int maycancel)
-{
- if (curthread->cancel_enable && maycancel)
- testcancel(curthread);
- curthread->cancel_point--;
-}
-
-void
-_thr_cancel_leave_defer(struct pthread *curthread, int maycancel)
+_thr_cancel_leave(struct pthread *curthread, int maycancel)
{
- if (curthread->cancel_enable && maycancel)
+ if (maycancel)
testcancel(curthread);
- curthread->cancel_point--;
- curthread->cancel_defer--;
+ curthread->cancel_point = 0;
}
Modified: head/lib/libthr/thread/thr_cond.c
==============================================================================
--- head/lib/libthr/thread/thr_cond.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_cond.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -210,10 +210,10 @@ cond_wait_common(pthread_cond_t *cond, p
if (cancel) {
THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info);
- _thr_cancel_enter_defer(curthread, 0);
+ _thr_cancel_enter2(curthread, 0);
ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 1);
info.cond = NULL;
- _thr_cancel_leave_defer(curthread, (ret != 0));
+ _thr_cancel_leave(curthread, (ret != 0));
THR_CLEANUP_POP(curthread, 0);
} else {
ret = _thr_ucond_wait(&cv->c_kerncv, &cv->c_lock, tsp, 0);
Modified: head/lib/libthr/thread/thr_create.c
==============================================================================
--- head/lib/libthr/thread/thr_create.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_create.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -127,11 +127,6 @@ _pthread_create(pthread_t * thread, cons
if (new_thread->attr.flags & PTHREAD_CREATE_DETACHED)
new_thread->tlflags |= TLFLAGS_DETACHED;
- if (curthread->in_sigcancel_handler)
- new_thread->unblock_sigcancel = 1;
- else
- new_thread->unblock_sigcancel = 0;
-
/* Add the new thread. */
new_thread->refcount = 1;
_thr_link(curthread, new_thread);
@@ -263,14 +258,6 @@ thread_start(struct pthread *curthread)
if (curthread->force_exit)
_pthread_exit(PTHREAD_CANCELED);
- if (curthread->unblock_sigcancel) {
- sigset_t set1;
-
- SIGEMPTYSET(set1);
- SIGADDSET(set1, SIGCANCEL);
- __sys_sigprocmask(SIG_UNBLOCK, &set1, NULL);
- }
-
if (curthread->attr.suspend == THR_CREATE_SUSPENDED) {
#if 0
/* Done in THR_UNLOCK() */
Modified: head/lib/libthr/thread/thr_exit.c
==============================================================================
--- head/lib/libthr/thread/thr_exit.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_exit.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -34,6 +34,8 @@
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
+#include <sys/types.h>
+#include <sys/signalvar.h>
#include "un-namespace.h"
#include "libc_private.h"
@@ -58,6 +60,12 @@ _thread_exit(const char *fname, int line
void
_pthread_exit(void *status)
{
+ _pthread_exit_mask(status, NULL);
+}
+
+void
+_pthread_exit_mask(void *status, sigset_t *mask)
+{
struct pthread *curthread = _get_curthread();
/* Check if this thread is already in the process of exiting: */
@@ -73,6 +81,17 @@ _pthread_exit(void *status)
curthread->cancelling = 1;
curthread->cancel_enable = 0;
curthread->cancel_async = 0;
+ curthread->cancel_point = 0;
+ if (mask != NULL)
+ __sys_sigprocmask(SIG_SETMASK, mask, NULL);
+ if (curthread->unblock_sigcancel) {
+ sigset_t set;
+
+ curthread->unblock_sigcancel = 0;
+ SIGEMPTYSET(set);
+ SIGADDSET(set, SIGCANCEL);
+ __sys_sigprocmask(SIG_UNBLOCK, mask, NULL);
+ }
/* Save the return value: */
curthread->ret = status;
Modified: head/lib/libthr/thread/thr_fork.c
==============================================================================
--- head/lib/libthr/thread/thr_fork.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_fork.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -115,6 +115,7 @@ __pthread_cxa_finalize(struct dl_phdr_in
}
THR_UMUTEX_UNLOCK(curthread, &_thr_atfork_lock);
_thr_tsd_unload(phdr_info);
+ _thr_sigact_unload(phdr_info);
}
__weak_reference(_fork, fork);
@@ -161,6 +162,7 @@ _fork(void)
* 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) {
@@ -182,6 +184,8 @@ _fork(void)
_thr_umutex_init(&curthread->lock);
_thr_umutex_init(&_thr_atfork_lock);
+ _thr_signal_postfork_child();
+
if (was_threaded)
_rtld_atfork_post(rtld_locks);
_thr_setthreaded(0);
@@ -211,6 +215,8 @@ _fork(void)
/* Parent process */
errsave = errno;
+ _thr_signal_postfork();
+
/* Ready to continue, unblock signals. */
_thr_signal_unblock(curthread);
Modified: head/lib/libthr/thread/thr_init.c
==============================================================================
--- head/lib/libthr/thread/thr_init.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_init.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -289,7 +289,6 @@ void
_libpthread_init(struct pthread *curthread)
{
int fd, first = 0;
- sigset_t sigset, oldset;
/* Check if this function has already been called: */
if ((_thr_initial != NULL) && (curthread == NULL))
@@ -347,13 +346,8 @@ _libpthread_init(struct pthread *curthre
_tcb_set(curthread->tcb);
if (first) {
- SIGFILLSET(sigset);
- SIGDELSET(sigset, SIGTRAP);
- __sys_sigprocmask(SIG_SETMASK, &sigset, &oldset);
- _thr_signal_init();
_thr_initial = curthread;
- SIGDELSET(oldset, SIGCANCEL);
- __sys_sigprocmask(SIG_SETMASK, &oldset, NULL);
+ _thr_signal_init();
if (_thread_event_mask & TD_CREATE)
_thr_report_creation(curthread, curthread);
}
Modified: head/lib/libthr/thread/thr_join.c
==============================================================================
--- head/lib/libthr/thread/thr_join.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_join.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -107,7 +107,7 @@ join_common(pthread_t pthread, void **th
THREAD_LIST_UNLOCK(curthread);
THR_CLEANUP_PUSH(curthread, backout_join, pthread);
- _thr_cancel_enter_defer(curthread, 1);
+ _thr_cancel_enter(curthread);
tid = pthread->tid;
while (pthread->tid != TID_TERMINATED) {
@@ -127,7 +127,7 @@ join_common(pthread_t pthread, void **th
break;
}
- _thr_cancel_leave_defer(curthread, 0);
+ _thr_cancel_leave(curthread, 0);
THR_CLEANUP_POP(curthread, 0);
if (ret == ETIMEDOUT) {
Modified: head/lib/libthr/thread/thr_kern.c
==============================================================================
--- head/lib/libthr/thread/thr_kern.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_kern.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -61,38 +61,6 @@ _thr_setthreaded(int threaded)
}
void
-_thr_signal_block(struct pthread *curthread)
-{
- sigset_t set;
-
- if (curthread->sigblock > 0) {
- curthread->sigblock++;
- return;
- }
- SIGFILLSET(set);
- SIGDELSET(set, SIGBUS);
- SIGDELSET(set, SIGILL);
- SIGDELSET(set, SIGFPE);
- SIGDELSET(set, SIGSEGV);
- SIGDELSET(set, SIGTRAP);
- __sys_sigprocmask(SIG_BLOCK, &set, &curthread->sigmask);
- curthread->sigblock++;
-}
-
-void
-_thr_signal_unblock(struct pthread *curthread)
-{
- if (--curthread->sigblock == 0)
- __sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
-}
-
-int
-_thr_send_sig(struct pthread *thread, int sig)
-{
- return thr_kill(thread->tid, sig);
-}
-
-void
_thr_assert_lock_level()
{
PANIC("locklevel <= 0");
Modified: head/lib/libthr/thread/thr_private.h
==============================================================================
--- head/lib/libthr/thread/thr_private.h Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_private.h Wed Sep 1 02:18:33 2010 (r212076)
@@ -376,12 +376,21 @@ struct pthread {
/* Thread temporary signal mask. */
sigset_t sigmask;
- /* Thread is in SIGCANCEL handler. */
- int in_sigcancel_handler;
-
- /* New thread should unblock SIGCANCEL. */
+ /* Thread should unblock SIGCANCEL. */
int unblock_sigcancel;
+ /* In sigsuspend state */
+ int in_sigsuspend;
+
+ /* deferred signal info */
+ siginfo_t deferred_siginfo;
+
+ /* signal mask to restore. */
+ sigset_t deferred_sigmask;
+
+ /* the sigaction should be used for deferred signal. */
+ struct sigaction deferred_sigact;
+
/* Force new thread to exit. */
int force_exit;
@@ -629,6 +638,7 @@ void _thr_ref_delete_unlocked(struct pth
int _thr_find_thread(struct pthread *, struct pthread *, int) __hidden;
void _thr_rtld_init(void) __hidden;
void _thr_rtld_fini(void) __hidden;
+void _thr_rtld_postfork_child(void) __hidden;
int _thr_stack_alloc(struct pthread_attr *) __hidden;
void _thr_stack_free(struct pthread_attr *) __hidden;
void _thr_free(struct pthread *, struct pthread *) __hidden;
@@ -637,10 +647,8 @@ void _thread_cleanupspecific(void) __
void _thread_printf(int, const char *, ...) __hidden;
void _thr_spinlock_init(void) __hidden;
void _thr_cancel_enter(struct pthread *) __hidden;
-void _thr_cancel_leave(struct pthread *) __hidden;
-void _thr_cancel_leave2(struct pthread *, int) __hidden;
-void _thr_cancel_enter_defer(struct pthread *, int) __hidden;
-void _thr_cancel_leave_defer(struct pthread *, int) __hidden;
+void _thr_cancel_enter2(struct pthread *, int) __hidden;
+void _thr_cancel_leave(struct pthread *, int) __hidden;
void _thr_testcancel(struct pthread *) __hidden;
void _thr_signal_block(struct pthread *) __hidden;
void _thr_signal_unblock(struct pthread *) __hidden;
@@ -653,7 +661,6 @@ void _thr_hash_remove(struct pthread *)
struct pthread *_thr_hash_find(struct pthread *) __hidden;
void _thr_link(struct pthread *, struct pthread *) __hidden;
void _thr_unlink(struct pthread *, struct pthread *) __hidden;
-void _thr_suspend_check(struct pthread *) __hidden;
void _thr_assert_lock_level(void) __hidden __dead2;
void _thr_ast(struct pthread *) __hidden;
void _thr_once_init(void) __hidden;
@@ -662,6 +669,9 @@ void _thr_report_creation(struct pthread
void _thr_report_death(struct pthread *curthread) __hidden;
int _thr_getscheduler(lwpid_t, int *, struct sched_param *) __hidden;
int _thr_setscheduler(lwpid_t, int, const struct sched_param *) __hidden;
+void _thr_signal_prefork(void) __hidden;
+void _thr_signal_postfork(void) __hidden;
+void _thr_signal_postfork_child(void) __hidden;
int _rtp_to_schedparam(const struct rtprio *rtp, int *policy,
struct sched_param *param) __hidden;
int _schedparam_to_rtp(int policy, const struct sched_param *param,
@@ -672,6 +682,8 @@ int _sched_yield(void);
void _pthread_cleanup_push(void (*)(void *), void *);
void _pthread_cleanup_pop(int);
+void _pthread_exit_mask(void *status, sigset_t *mask) __dead2 __hidden;
+
/* #include <fcntl.h> */
#ifdef _SYS_FCNTL_H_
@@ -687,7 +699,7 @@ int __sys_sigaction(int, const struc
int __sys_sigpending(sigset_t *);
int __sys_sigprocmask(int, const sigset_t *, sigset_t *);
int __sys_sigsuspend(const sigset_t *);
-int __sys_sigreturn(ucontext_t *);
+int __sys_sigreturn(const ucontext_t *);
int __sys_sigaltstack(const struct sigaltstack *, struct sigaltstack *);
int __sys_sigwait(const sigset_t *, int *);
int __sys_sigtimedwait(const sigset_t *, siginfo_t *,
@@ -740,6 +752,7 @@ _thr_check_init(void)
struct dl_phdr_info;
void __pthread_cxa_finalize(struct dl_phdr_info *phdr_info);
void _thr_tsd_unload(struct dl_phdr_info *phdr_info) __hidden;
+void _thr_sigact_unload(struct dl_phdr_info *phdr_info) __hidden;
__END_DECLS
Modified: head/lib/libthr/thread/thr_rtld.c
==============================================================================
--- head/lib/libthr/thread/thr_rtld.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_rtld.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -32,6 +32,7 @@
*/
#include <sys/cdefs.h>
#include <stdlib.h>
+#include <string.h>
#include "rtld_lock.h"
#include "thr_private.h"
@@ -132,7 +133,7 @@ _thr_rtld_wlock_acquire(void *lock)
SAVE_ERRNO();
l = (struct rtld_lock *)lock;
- _thr_signal_block(curthread);
+ THR_CRITICAL_ENTER(curthread);
while (_thr_rwlock_wrlock(&l->lock, NULL) != 0)
;
RESTORE_ERRNO();
@@ -152,12 +153,9 @@ _thr_rtld_lock_release(void *lock)
state = l->lock.rw_state;
if (_thr_rwlock_unlock(&l->lock) == 0) {
- if ((state & URWLOCK_WRITE_OWNER) == 0) {
+ if ((state & URWLOCK_WRITE_OWNER) == 0)
curthread->rdlock_count--;
- THR_CRITICAL_LEAVE(curthread);
- } else {
- _thr_signal_unblock(curthread);
- }
+ THR_CRITICAL_LEAVE(curthread);
}
RESTORE_ERRNO();
}
@@ -193,6 +191,9 @@ _thr_rtld_init(void)
/* force to resolve errno() PLT */
__error();
+ /* force to resolve memcpy PLT */
+ memcpy(&dummy, &dummy, sizeof(dummy));
+
li.lock_create = _thr_rtld_lock_create;
li.lock_destroy = _thr_rtld_lock_destroy;
li.rlock_acquire = _thr_rtld_rlock_acquire;
Modified: head/lib/libthr/thread/thr_sig.c
==============================================================================
--- head/lib/libthr/thread/thr_sig.c Wed Sep 1 01:26:07 2010 (r212075)
+++ head/lib/libthr/thread/thr_sig.c Wed Sep 1 02:18:33 2010 (r212076)
@@ -32,11 +32,10 @@
#include <sys/signalvar.h>
#include <signal.h>
#include <errno.h>
-#include <fcntl.h>
-#include <unistd.h>
#include <string.h>
#include <pthread.h>
#include "un-namespace.h"
+#include "libc_private.h"
#include "thr_private.h"
@@ -47,7 +46,19 @@
#define DBG_MSG(x...)
#endif
-extern int __pause(void);
+struct usigaction {
+ struct sigaction sigact;
+ struct urwlock lock;
+};
+
+static struct usigaction _thr_sigact[_SIG_MAXSIG];
+
+static void thr_sighandler(int, siginfo_t *, void *);
+static void handle_signal(struct sigaction *, int, siginfo_t *, ucontext_t *);
+static void check_deferred_signal(struct pthread *);
+static void check_suspend(struct pthread *);
+static void check_cancel(struct pthread *curthread, ucontext_t *ucp);
+
int ___pause(void);
int _raise(int);
int __sigtimedwait(const sigset_t *set, siginfo_t *info,
@@ -59,10 +70,49 @@ int _sigwaitinfo(const sigset_t *set, si
int __sigwait(const sigset_t *set, int *sig);
int _sigwait(const sigset_t *set, int *sig);
int __sigsuspend(const sigset_t *sigmask);
+int _sigaction(int, const struct sigaction *, struct sigaction *);
int _setcontext(const ucontext_t *);
int _swapcontext(ucontext_t *, const ucontext_t *);
-static void
+static const sigset_t _thr_deferset={{
+ 0xffffffff & ~(_SIG_BIT(SIGBUS)|_SIG_BIT(SIGILL)|_SIG_BIT(SIGFPE)|
+ _SIG_BIT(SIGSEGV)|_SIG_BIT(SIGTRAP)|_SIG_BIT(SIGSYS)),
+ 0xffffffff,
+ 0xffffffff,
+ 0xffffffff}};
+
+static const sigset_t _thr_maskset={{
+ 0xffffffff,
+ 0xffffffff,
+ 0xffffffff,
+ 0xffffffff}};
+
+void
+_thr_signal_block(struct pthread *curthread)
+{
+
+ if (curthread->sigblock > 0) {
+ curthread->sigblock++;
+ return;
+ }
+ __sys_sigprocmask(SIG_BLOCK, &_thr_maskset, &curthread->sigmask);
+ curthread->sigblock++;
+}
+
+void
+_thr_signal_unblock(struct pthread *curthread)
+{
+ if (--curthread->sigblock == 0)
+ __sys_sigprocmask(SIG_SETMASK, &curthread->sigmask, NULL);
+}
+
+int
+_thr_send_sig(struct pthread *thread, int sig)
+{
+ return thr_kill(thread->tid, sig);
+}
+
+static inline void
remove_thr_signals(sigset_t *set)
{
if (SIGISMEMBER(*set, SIGCANCEL))
@@ -72,87 +122,244 @@ remove_thr_signals(sigset_t *set)
static const sigset_t *
thr_remove_thr_signals(const sigset_t *set, sigset_t *newset)
{
- const sigset_t *pset;
-
- if (SIGISMEMBER(*set, SIGCANCEL)) {
- *newset = *set;
- SIGDELSET(*newset, SIGCANCEL);
- pset = newset;
- } else
- pset = set;
- return (pset);
+ *newset = *set;
+ remove_thr_signals(newset);
+ return (newset);
}
static void
sigcancel_handler(int sig __unused,
- siginfo_t *info __unused, ucontext_t *ucp __unused)
+ siginfo_t *info __unused, ucontext_t *ucp)
+{
+ struct pthread *curthread = _get_curthread();
+ int err;
+
+ if (THR_IN_CRITICAL(curthread))
+ return;
+ err = errno;
+ check_suspend(curthread);
+ check_cancel(curthread, ucp);
+ errno = err;
+}
+
+typedef void (*ohandler)(int sig, int code,
+ struct sigcontext *scp, char *addr, __sighandler_t *catcher);
+
+/*
+ * The signal handler wrapper is entered with all signal masked.
+ */
+static void
+thr_sighandler(int sig, siginfo_t *info, void *_ucp)
+{
+ struct pthread *curthread = _get_curthread();
+ ucontext_t *ucp = _ucp;
+ struct sigaction act;
+ int err;
+
+ err = errno;
+ _thr_rwl_rdlock(&_thr_sigact[sig-1].lock);
+ act = _thr_sigact[sig-1].sigact;
+ _thr_rwl_unlock(&_thr_sigact[sig-1].lock);
+ errno = err;
+
+ /*
+ * if a thread is in critical region, for example it holds low level locks,
+ * try to defer the signal processing, however if the signal is synchronous
+ * signal, it means a bad thing has happened, this is a programming error,
+ * resuming fault point can not help anything (normally causes deadloop),
+ * so here we let user code handle it immediately.
+ */
+ if (THR_IN_CRITICAL(curthread) && SIGISMEMBER(_thr_deferset, sig)) {
+ memcpy(&curthread->deferred_sigact, &act, sizeof(struct sigaction));
+ memcpy(&curthread->deferred_siginfo, info, sizeof(siginfo_t));
+ curthread->deferred_sigmask = ucp->uc_sigmask;
+ /* mask all signals, we will restore it later. */
+ ucp->uc_sigmask = _thr_deferset;
+ return;
+ }
+
+ handle_signal(&act, sig, info, ucp);
+}
+
+static void
+handle_signal(struct sigaction *actp, int sig, siginfo_t *info, ucontext_t *ucp)
{
struct pthread *curthread = _get_curthread();
+ ucontext_t uc2;
+ __siginfohandler_t *sigfunc;
+ int cancel_defer;
+ int cancel_point;
+ int cancel_async;
+ int cancel_enable;
+ int in_sigsuspend;
+ int err;
+
+ /* add previous level mask */
+ SIGSETOR(actp->sa_mask, ucp->uc_sigmask);
+
+ /* add this signal's mask */
+ if (!(actp->sa_flags & SA_NODEFER))
+ SIGADDSET(actp->sa_mask, sig);
+
+ in_sigsuspend = curthread->in_sigsuspend;
+ curthread->in_sigsuspend = 0;
+
+ /*
+ * if thread is in deferred cancellation mode, disable cancellation
+ * in signal handler.
+ * if user signal handler calls a cancellation point function, e.g,
+ * it calls write() to write data to file, because write() is a
+ * cancellation point, the thread is immediately cancelled if
+ * cancellation is pending, to avoid this problem while thread is in
+ * deferring mode, cancellation is temporarily disabled.
+ */
+ cancel_defer = curthread->cancel_defer;
+ cancel_point = curthread->cancel_point;
+ cancel_async = curthread->cancel_async;
+ cancel_enable = curthread->cancel_enable;
+ curthread->cancel_point = 0;
+ curthread->cancel_defer = 0;
+ if (!cancel_async)
+ curthread->cancel_enable = 0;
- curthread->in_sigcancel_handler++;
- _thr_ast(curthread);
- curthread->in_sigcancel_handler--;
+ /* restore correct mask before calling user handler */
+ __sys_sigprocmask(SIG_SETMASK, &actp->sa_mask, NULL);
+
+ sigfunc = actp->sa_sigaction;
+
+ /*
+ * We have already reset cancellation point flags, so if user's code
+ * longjmp()s out of its signal handler, wish its jmpbuf was set
+ * outside of a cancellation point, in most cases, this would be
+ * true. however, ther is no way to save cancel_enable in jmpbuf,
+ * so after setjmps() returns once more, the user code may need to
+ * re-set cancel_enable flag by calling pthread_setcancelstate().
+ */
+ if ((actp->sa_flags & SA_SIGINFO) != 0)
+ (*(sigfunc))(sig, info, ucp);
+ else {
+ ((ohandler)(*sigfunc))(
+ sig, info->si_code, (struct sigcontext *)ucp,
+ info->si_addr, (__sighandler_t *)sigfunc);
+ }
+ err = errno;
+
+ curthread->in_sigsuspend = in_sigsuspend;
+ curthread->cancel_defer = cancel_defer;
+ curthread->cancel_point = cancel_point;
+ curthread->cancel_enable = cancel_enable;
+
+ memcpy(&uc2, ucp, sizeof(uc2));
+ SIGDELSET(uc2.uc_sigmask, SIGCANCEL);
+
+ /* reschedule cancellation */
+ check_cancel(curthread, &uc2);
+ errno = err;
+ __sys_sigreturn(&uc2);
}
void
_thr_ast(struct pthread *curthread)
{
- if (THR_IN_CRITICAL(curthread))
+ if (!THR_IN_CRITICAL(curthread)) {
+ check_deferred_signal(curthread);
+ check_suspend(curthread);
+ check_cancel(curthread, NULL);
+ }
+}
+
+/* reschedule cancellation */
+static void
+check_cancel(struct pthread *curthread, ucontext_t *ucp)
+{
+
+ if (__predict_true(!curthread->cancel_pending || !curthread->cancel_enable ||
+ curthread->cancelling))
return;
- if (curthread->cancel_pending && curthread->cancel_enable
- && !curthread->cancelling) {
- if (curthread->cancel_async) {
- /*
- * asynchronous cancellation mode, act upon
- * immediately.
- */
- _pthread_exit(PTHREAD_CANCELED);
- } else {
- /*
- * Otherwise, we are in defer mode, and we are at
- * cancel point, tell kernel to not block the current
- * thread on next cancelable system call.
- *
- * There are two cases we should call thr_wake() to
- * turn on TDP_WAKEUP in kernel:
- * 1) we are going to call a cancelable system call,
- * non-zero cancel_point means we are already in
- * cancelable state, next system call is cancelable.
- * 2) because _thr_ast() may be called by
- * THR_CRITICAL_LEAVE() which is used by rtld rwlock
- * and any libthr internal locks, when rtld rwlock
- * is used, it is mostly caused my an unresolved PLT.
- * those routines may clear the TDP_WAKEUP flag by
- * invoking some system calls, in those cases, we
- * also should reenable the flag.
- */
- if (curthread->cancel_point) {
- if (curthread->cancel_defer)
- thr_wake(curthread->tid);
- else
- _pthread_exit(PTHREAD_CANCELED);
- }
+ if (curthread->cancel_async) {
+ /*
+ * asynchronous cancellation mode, act upon
+ * immediately.
+ */
+ _pthread_exit_mask(PTHREAD_CANCELED,
+ ucp? &ucp->uc_sigmask : NULL);
+ } else {
+ /*
+ * Otherwise, we are in defer mode, and we are at
+ * cancel point, tell kernel to not block the current
+ * thread on next cancelable system call.
+ *
+ * There are three cases we should call thr_wake() to
+ * turn on TDP_WAKEUP or send SIGCANCEL in kernel:
+ * 1) we are going to call a cancelable system call,
+ * non-zero cancel_point means we are already in
+ * cancelable state, next system call is cancelable.
+ * 2) because _thr_ast() may be called by
+ * THR_CRITICAL_LEAVE() which is used by rtld rwlock
+ * and any libthr internal locks, when rtld rwlock
+ * is used, it is mostly caused my an unresolved PLT.
+ * those routines may clear the TDP_WAKEUP flag by
+ * invoking some system calls, in those cases, we
+ * also should reenable the flag.
+ * 3) thread is in sigsuspend(), and the syscall insists
+ * on getting a signal before it agrees to return.
+ */
+ if (curthread->cancel_point) {
+ if (curthread->in_sigsuspend && ucp) {
+ SIGADDSET(ucp->uc_sigmask, SIGCANCEL);
+ curthread->unblock_sigcancel = 1;
+ _thr_send_sig(curthread, SIGCANCEL);
+ } else
+ thr_wake(curthread->tid);
}
}
+}
+
+static void
+check_deferred_signal(struct pthread *curthread)
+{
+ ucontext_t uc;
+ struct sigaction act;
+ siginfo_t info;
+ volatile int first;
- if (__predict_false((curthread->flags &
- (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED))
- == THR_FLAGS_NEED_SUSPEND))
- _thr_suspend_check(curthread);
+ if (__predict_true(curthread->deferred_siginfo.si_signo == 0))
+ return;
+ first = 1;
+ getcontext(&uc);
+ if (first) {
+ first = 0;
+ act = curthread->deferred_sigact;
+ uc.uc_sigmask = curthread->deferred_sigmask;
+ memcpy(&info, &curthread->deferred_siginfo, sizeof(siginfo_t));
+ /* remove signal */
+ curthread->deferred_siginfo.si_signo = 0;
+ if (act.sa_flags & SA_RESETHAND) {
+ struct sigaction tact;
+
+ tact = act;
+ tact.sa_handler = SIG_DFL;
+ _sigaction(info.si_signo, &tact, NULL);
+ }
+ handle_signal(&act, info.si_signo, &info, &uc);
+ }
}
-void
-_thr_suspend_check(struct pthread *curthread)
+static void
+check_suspend(struct pthread *curthread)
{
uint32_t cycle;
- int err;
+
+ if (__predict_true((curthread->flags &
+ (THR_FLAGS_NEED_SUSPEND | THR_FLAGS_SUSPENDED))
+ != THR_FLAGS_NEED_SUSPEND))
+ return;
if (curthread->force_exit)
return;
- err = errno;
/*
* Blocks SIGCANCEL which other threads must send.
*/
@@ -188,15 +395,7 @@ _thr_suspend_check(struct pthread *curth
THR_UMUTEX_UNLOCK(curthread, &(curthread)->lock);
curthread->critical_count--;
- /*
- * Unblocks SIGCANCEL, it is possible a new SIGCANCEL is ready and
- * a new signal frame will nest us, this seems a problem because
- * stack will grow and overflow, but because kernel will automatically
- * mask the SIGCANCEL when delivering the signal, so we at most only
- * have one nesting signal frame, this should be fine.
- */
_thr_signal_unblock(curthread);
- errno = err;
}
void
@@ -204,11 +403,80 @@ _thr_signal_init(void)
{
struct sigaction act;
- /* Install cancel handler. */
- SIGEMPTYSET(act.sa_mask);
- act.sa_flags = SA_SIGINFO | SA_RESTART;
+ /* Install SIGCANCEL handler. */
+ SIGFILLSET(act.sa_mask);
+ act.sa_flags = SA_SIGINFO;
act.sa_sigaction = (__siginfohandler_t *)&sigcancel_handler;
__sys_sigaction(SIGCANCEL, &act, NULL);
+
+ /* Unblock SIGCANCEL */
+ SIGEMPTYSET(act.sa_mask);
+ SIGADDSET(act.sa_mask, SIGCANCEL);
+ __sys_sigprocmask(SIG_UNBLOCK, &act.sa_mask, NULL);
+}
+
+/*
+ * called from rtld with rtld_lock locked, because rtld_lock is
+ * a critical region, so all signals have already beeen masked.
+ */
+void
+_thr_sigact_unload(struct dl_phdr_info *phdr_info)
+{
+ struct urwlock *rwlp;
+ struct sigaction *actp;
+ struct sigaction kact;
+ void (*handler)(int);
+ int sig;
+
+ for (sig = 1; sig < _SIG_MAXSIG; sig++) {
+ actp = &_thr_sigact[sig].sigact;
+retry:
+ handler = actp->sa_handler;
+ if (handler != SIG_DFL && handler != SIG_IGN &&
+ __elf_phdr_match_addr(phdr_info, handler)) {
+ rwlp = &_thr_sigact[sig].lock;
+ _thr_rwl_wrlock(rwlp);
+ if (handler != actp->sa_handler) {
+ _thr_rwl_unlock(rwlp);
+ goto retry;
+ }
+ actp->sa_handler = SIG_DFL;
+ actp->sa_flags = SA_SIGINFO;
+ SIGEMPTYSET(actp->sa_mask);
+ if (__sys_sigaction(sig, NULL, &kact) == 0 &&
+ kact.sa_handler != SIG_DFL &&
+ kact.sa_handler != SIG_IGN)
+ __sys_sigaction(sig, actp, NULL);
+ _thr_rwl_unlock(rwlp);
+ }
+ }
+}
+
+void
+_thr_signal_prefork(void)
+{
+ int i;
+
+ for (i = 1; i < _SIG_MAXSIG; ++i)
+ _thr_rwl_rdlock(&_thr_sigact[i-1].lock);
+}
+
+void
+_thr_signal_postfork(void)
+{
+ int i;
+
+ for (i = 1; i < _SIG_MAXSIG; ++i)
+ _thr_rwl_unlock(&_thr_sigact[i-1].lock);
+}
+
+void
+_thr_signal_postfork_child(void)
+{
+ int i;
+
+ for (i = 1; i < _SIG_MAXSIG; ++i)
+ bzero(&_thr_sigact[i-1].lock, sizeof(struct urwlock));
}
void
@@ -221,14 +489,11 @@ __weak_reference(___pause, pause);
int
___pause(void)
{
- struct pthread *curthread = _get_curthread();
- int ret;
+ sigset_t oset;
- _thr_cancel_enter(curthread);
- ret = __pause();
- _thr_cancel_leave(curthread);
-
- return ret;
+ if (_sigprocmask(SIG_BLOCK, NULL, &oset) == -1)
+ return (-1);
+ return (__sigsuspend(&oset));
}
__weak_reference(_raise, raise);
@@ -236,13 +501,7 @@ __weak_reference(_raise, raise);
int
_raise(int sig)
{
- int ret;
-
- if (!_thr_isthreaded())
- ret = kill(getpid(), sig);
- else
- ret = _thr_send_sig(_get_curthread(), sig);
- return (ret);
+ return _thr_send_sig(_get_curthread(), sig);
}
__weak_reference(_sigaction, sigaction);
@@ -250,14 +509,65 @@ __weak_reference(_sigaction, sigaction);
int
_sigaction(int sig, const struct sigaction * act, struct sigaction * oact)
{
- /* Check if the signal number is out of range: */
+ struct sigaction newact, oldact, oldact2;
+ sigset_t oldset;
+ int ret = 0, err = 0;
+
if (!_SIG_VALID(sig) || sig == SIGCANCEL) {
- /* Return an invalid argument: */
errno = EINVAL;
return (-1);
}
- return __sys_sigaction(sig, act, oact);
+ if (act)
+ newact = *act;
+
+ __sys_sigprocmask(SIG_SETMASK, &_thr_maskset, &oldset);
+ _thr_rwl_wrlock(&_thr_sigact[sig-1].lock);
+
+ if (act != NULL) {
+ oldact2 = _thr_sigact[sig-1].sigact;
+
+ /*
+ * if a new sig handler is SIG_DFL or SIG_IGN,
+ * don't remove old handler from _thr_sigact[],
+ * so deferred signals still can use the handlers,
+ * multiple threads invoking sigaction itself is
+ * a race condition, so it is not a problem.
+ */
+ if (newact.sa_handler != SIG_DFL &&
+ newact.sa_handler != SIG_IGN) {
+ _thr_sigact[sig-1].sigact = newact;
+ remove_thr_signals(
+ &_thr_sigact[sig-1].sigact.sa_mask);
+ newact.sa_flags &= ~SA_NODEFER;
+ newact.sa_flags |= SA_SIGINFO;
+ newact.sa_sigaction = thr_sighandler;
+ newact.sa_mask = _thr_maskset; /* mask all signals */
+ }
+ if ((ret = __sys_sigaction(sig, &newact, &oldact))) {
+ err = errno;
+ _thr_sigact[sig-1].sigact = oldact2;
+ }
+ } else if (oact != NULL) {
+ ret = __sys_sigaction(sig, NULL, &oldact);
+ err = errno;
+ }
+
+ if (oldact.sa_handler != SIG_DFL &&
+ oldact.sa_handler != SIG_IGN) {
+ oldact = _thr_sigact[sig-1].sigact;
+ }
+
+ _thr_rwl_unlock(&_thr_sigact[sig-1].lock);
*** DIFF OUTPUT TRUNCATED AT 1000 LINES ***
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