2701
2702 //
2703 // Handler function invoked when a thread's execution is suspended or
2704 // resumed. We have to be careful that only async-safe functions are
2705 // called here (Note: most pthread functions are not async safe and
2706 // should be avoided.)
2707 //
2708 // Note: sigwait() is a more natural fit than sigsuspend() from an
2709 // interface point of view, but sigwait() prevents the signal hander
2710 // from being run. libpthread would get very confused by not having
2711 // its signal handlers run and prevents sigwait()'s use with the
2712 // mutex granting granting signal.
2713 //
2714 // Currently only ever called on the VMThread and JavaThreads (PC sampling).
2715 //
2716 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
2717 // Save and restore errno to avoid confusing native code with EINTR
2718 // after sigsuspend.
2719 int old_errno = errno;
2720
2721 Thread* thread = Thread::current();
2722 OSThread* osthread = thread->osthread();
2723 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
2724
2725 os::SuspendResume::State current = osthread->sr.state();
2726 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
2727 suspend_save_context(osthread, siginfo, context);
2728
2729 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
2730 os::SuspendResume::State state = osthread->sr.suspended();
2731 if (state == os::SuspendResume::SR_SUSPENDED) {
2732 sigset_t suspend_set; // signals for sigsuspend()
2733
2734 // get current set of blocked signals and unblock resume signal
2735 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
2736 sigdelset(&suspend_set, SR_signum);
2737
2738 // wait here until we are resumed
2739 while (1) {
2740 sigsuspend(&suspend_set);
2741
2742 os::SuspendResume::State result = osthread->sr.running();
2743 if (result == os::SuspendResume::SR_RUNNING) {
|
2701
2702 //
2703 // Handler function invoked when a thread's execution is suspended or
2704 // resumed. We have to be careful that only async-safe functions are
2705 // called here (Note: most pthread functions are not async safe and
2706 // should be avoided.)
2707 //
2708 // Note: sigwait() is a more natural fit than sigsuspend() from an
2709 // interface point of view, but sigwait() prevents the signal hander
2710 // from being run. libpthread would get very confused by not having
2711 // its signal handlers run and prevents sigwait()'s use with the
2712 // mutex granting granting signal.
2713 //
2714 // Currently only ever called on the VMThread and JavaThreads (PC sampling).
2715 //
2716 static void SR_handler(int sig, siginfo_t* siginfo, ucontext_t* context) {
2717 // Save and restore errno to avoid confusing native code with EINTR
2718 // after sigsuspend.
2719 int old_errno = errno;
2720
2721 Thread* thread = Thread::current_or_null_safe();
2722 assert(thread != NULL, "Missing current thread in SR_handler");
2723
2724 // On some systems we have seen signal delivery get "stuck" until the signal
2725 // mask is changed as part of thread termination. Check the current thread
2726 // has not already terminated (via SR_lock()) - else the following assertion
2727 // will fail because the thread is no longer a JavaThread as the ~JavaThread
2728 // destructor has completed.
2729
2730 if (thread->SR_lock() == NULL)
2731 return;
2732
2733 assert(thread->is_VM_thread() || thread->is_Java_thread(), "Must be VMThread or JavaThread");
2734
2735 OSThread* osthread = thread->osthread();
2736
2737 os::SuspendResume::State current = osthread->sr.state();
2738 if (current == os::SuspendResume::SR_SUSPEND_REQUEST) {
2739 suspend_save_context(osthread, siginfo, context);
2740
2741 // attempt to switch the state, we assume we had a SUSPEND_REQUEST
2742 os::SuspendResume::State state = osthread->sr.suspended();
2743 if (state == os::SuspendResume::SR_SUSPENDED) {
2744 sigset_t suspend_set; // signals for sigsuspend()
2745
2746 // get current set of blocked signals and unblock resume signal
2747 pthread_sigmask(SIG_BLOCK, NULL, &suspend_set);
2748 sigdelset(&suspend_set, SR_signum);
2749
2750 // wait here until we are resumed
2751 while (1) {
2752 sigsuspend(&suspend_set);
2753
2754 os::SuspendResume::State result = osthread->sr.running();
2755 if (result == os::SuspendResume::SR_RUNNING) {
|