/* * Copyright (C) 2001 Julian Elischer . * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice(s), this list of conditions and the following disclaimer as * the first lines of this file unmodified other than the possible * addition of one or more copyright notices. * 2. Redistributions in binary form must reproduce the above copyright * notice(s), this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * $FreeBSD$ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * KSEGRP related storage. */ static uma_zone_t ksegrp_zone; static uma_zone_t kse_zone; static uma_zone_t thread_zone; /* DEBUG ONLY */ SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); static int oiks_debug = 1; /* 0 disable, 1 printf, 2 enter debugger */ SYSCTL_INT(_kern_threads, OID_AUTO, oiks, CTLFLAG_RW, &oiks_debug, 0, "OIKS thread debug"); static int max_threads_per_proc = 6; SYSCTL_INT(_kern_threads, OID_AUTO, max_per_proc, CTLFLAG_RW, &max_threads_per_proc, 0, "Limit on threads per proc"); #define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start)) struct threadqueue zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); struct mtx zombie_thread_lock; MTX_SYSINIT(zombie_thread_lock, &zombie_thread_lock, "zombie_thread_lock", MTX_SPIN); /* * Pepare a thread for use. */ static void thread_ctor(void *mem, int size, void *arg) { struct thread *td; KASSERT((size == sizeof(struct thread)), ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); td = (struct thread *)mem; td->td_state = TDS_INACTIVE; td->td_flags |= TDF_UNBOUND; } /* * Reclaim a thread after use. */ static void thread_dtor(void *mem, int size, void *arg) { struct thread *td; KASSERT((size == sizeof(struct thread)), ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); td = (struct thread *)mem; #ifdef INVARIANTS /* Verify that this thread is in a safe state to free. */ switch (td->td_state) { case TDS_INHIBITED: case TDS_RUNNING: case TDS_CAN_RUN: case TDS_RUNQ: /* * We must never unlink a thread that is in one of * these states, because it is currently active. */ panic("bad state for thread unlinking"); /* NOTREACHED */ case TDS_INACTIVE: break; default: panic("bad thread state"); /* NOTREACHED */ } #endif } /* * Initialize type-stable parts of a thread (when newly created). */ static void thread_init(void *mem, int size) { struct thread *td; KASSERT((size == sizeof(struct thread)), ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); td = (struct thread *)mem; mtx_lock(&Giant); pmap_new_thread(td, 0); mtx_unlock(&Giant); cpu_thread_setup(td); } /* * Tear down type-stable parts of a thread (just before being discarded). */ static void thread_fini(void *mem, int size) { struct thread *td; KASSERT((size == sizeof(struct thread)), ("size mismatch: %d != %d\n", size, (int)sizeof(struct thread))); td = (struct thread *)mem; pmap_dispose_thread(td); } /* * Fill a ucontext_t with a thread's context information. * * This is an analogue to getcontext(3). */ void thread_getcontext(struct thread *td, ucontext_t *uc) { /* * XXX this is declared in a MD include file, i386/include/ucontext.h but * is used in MI code. */ #ifdef __i386__ get_mcontext(td, &uc->uc_mcontext); #endif uc->uc_sigmask = td->td_proc->p_sigmask; } /* * Set a thread's context from a ucontext_t. * * This is an analogue to setcontext(3). */ int thread_setcontext(struct thread *td, ucontext_t *uc) { int ret; /* * XXX this is declared in a MD include file, i386/include/ucontext.h but * is used in MI code. */ #ifdef __i386__ ret = set_mcontext(td, &uc->uc_mcontext); #else ret = ENOSYS; #endif if (ret == 0) { SIG_CANTMASK(uc->uc_sigmask); PROC_LOCK(td->td_proc); td->td_proc->p_sigmask = uc->uc_sigmask; PROC_UNLOCK(td->td_proc); } return (ret); } /* * Initialize global thread allocation resources. */ void threadinit(void) { #ifndef __ia64__ thread_zone = uma_zcreate("THREAD", sizeof (struct thread), thread_ctor, thread_dtor, thread_init, thread_fini, UMA_ALIGN_CACHE, 0); #else /* * XXX the ia64 kstack allocator is really lame and is at the mercy * of contigmallloc(). This hackery is to pre-construct a whole * pile of thread structures with associated kernel stacks early * in the system startup while contigmalloc() still works. Once we * have them, keep them. Sigh. */ thread_zone = uma_zcreate("THREAD", sizeof (struct thread), thread_ctor, thread_dtor, thread_init, thread_fini, UMA_ALIGN_CACHE, UMA_ZONE_NOFREE); uma_prealloc(thread_zone, 512); /* XXX arbitary */ #endif ksegrp_zone = uma_zcreate("KSEGRP", sizeof (struct ksegrp), NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0); kse_zone = uma_zcreate("KSE", sizeof (struct kse), NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0); } /* * Stash an embarasingly extra thread into the zombie thread queue. */ void thread_stash(struct thread *td) { mtx_lock_spin(&zombie_thread_lock); TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq); mtx_unlock_spin(&zombie_thread_lock); } /* * Reap zombie threads. */ void thread_reap(void) { struct thread *td_reaped; /* * don't even bother to lock if none at this instant * We really don't care about the next instant.. */ if (!TAILQ_EMPTY(&zombie_threads)) { mtx_lock_spin(&zombie_thread_lock); while (!TAILQ_EMPTY(&zombie_threads)) { td_reaped = TAILQ_FIRST(&zombie_threads); TAILQ_REMOVE(&zombie_threads, td_reaped, td_runq); mtx_unlock_spin(&zombie_thread_lock); thread_free(td_reaped); mtx_lock_spin(&zombie_thread_lock); } mtx_unlock_spin(&zombie_thread_lock); } } /* * Allocate a ksegrp. */ struct ksegrp * ksegrp_alloc(void) { return (uma_zalloc(ksegrp_zone, M_WAITOK)); } /* * Allocate a kse. */ struct kse * kse_alloc(void) { return (uma_zalloc(kse_zone, M_WAITOK)); } /* * Allocate a thread. */ struct thread * thread_alloc(void) { thread_reap(); /* check if any zombies to get */ return (uma_zalloc(thread_zone, M_WAITOK)); } /* * Deallocate a ksegrp. */ void ksegrp_free(struct ksegrp *td) { uma_zfree(ksegrp_zone, td); } /* * Deallocate a kse. */ void kse_free(struct kse *td) { uma_zfree(kse_zone, td); } /* * Deallocate a thread. */ void thread_free(struct thread *td) { uma_zfree(thread_zone, td); } /* * Store the thread context in the UTS's mailbox. * then add the mailbox at the head of a list we are building in user space. * The list is anchored in the ksegrp structure. */ int thread_export_context(struct thread *td) { struct proc *p; struct ksegrp *kg; uintptr_t mbx; void *addr; int error; ucontext_t uc; p = td->td_proc; kg = td->td_ksegrp; /* Export the user/machine context. */ #if 0 addr = (caddr_t)td->td_mailbox + offsetof(struct kse_thr_mailbox, tm_context); #else /* if user pointer arithmetic is valid in the kernel */ addr = (void *)(&td->td_mailbox->tm_context); #endif error = copyin(addr, &uc, sizeof(ucontext_t)); if (error == 0) { thread_getcontext(td, &uc); error = copyout(&uc, addr, sizeof(ucontext_t)); } if (error) { PROC_LOCK(p); psignal(p, SIGSEGV); PROC_UNLOCK(p); return (error); } /* get address in latest mbox of list pointer */ #if 0 addr = (caddr_t)td->td_mailbox + offsetof(struct kse_thr_mailbox , tm_next); #else /* if user pointer arithmetic is valid in the kernel */ addr = (void *)(&td->td_mailbox->tm_next); #endif /* * Put the saved address of the previous first * entry into this one */ for (;;) { mbx = (uintptr_t)kg->kg_completed; if (suword(addr, mbx)) { PROC_LOCK(p); psignal(p, SIGSEGV); PROC_UNLOCK(p); return (EFAULT); } PROC_LOCK(p); if (mbx == (uintptr_t)kg->kg_completed) { kg->kg_completed = td->td_mailbox; PROC_UNLOCK(p); break; } PROC_UNLOCK(p); } return (0); } /* * Take the list of completed mailboxes for this KSEGRP and put them on this * KSE's mailbox as it's the next one going up. */ static int thread_link_mboxes(struct ksegrp *kg, struct kse *ke) { struct proc *p = kg->kg_proc; void *addr; uintptr_t mbx; #if 0 addr = (caddr_t)ke->ke_mailbox + offsetof(struct kse_mailbox, km_completed); #else /* if user pointer arithmetic is valid in the kernel */ addr = (void *)(&ke->ke_mailbox->km_completed); #endif for (;;) { mbx = (uintptr_t)kg->kg_completed; if (suword(addr, mbx)) { PROC_LOCK(p); psignal(p, SIGSEGV); PROC_UNLOCK(p); return (EFAULT); } /* XXXKSE could use atomic CMPXCH here */ PROC_LOCK(p); if (mbx == (uintptr_t)kg->kg_completed) { kg->kg_completed = NULL; PROC_UNLOCK(p); break; } PROC_UNLOCK(p); } return (0); } /* * Discard the current thread and exit from its context. * * Because we can't free a thread while we're operating under its context, * push the current thread into our KSE's ke_tdspare slot, freeing the * thread that might be there currently. Because we know that only this * processor will run our KSE, we needn't worry about someone else grabbing * our context before we do a cpu_throw. */ void thread_exit(void) { struct thread *td; struct kse *ke; struct proc *p; struct ksegrp *kg; td = curthread; kg = td->td_ksegrp; p = td->td_proc; ke = td->td_kse; mtx_assert(&sched_lock, MA_OWNED); KASSERT(p != NULL, ("thread exiting without a process")); KASSERT(ke != NULL, ("thread exiting without a kse")); KASSERT(kg != NULL, ("thread exiting without a kse group")); PROC_LOCK_ASSERT(p, MA_OWNED); CTR1(KTR_PROC, "thread_exit: thread %p", td); KASSERT(!mtx_owned(&Giant), ("dying thread owns giant")); if (ke->ke_tdspare != NULL) { thread_stash(ke->ke_tdspare); ke->ke_tdspare = NULL; } cpu_thread_exit(td); /* XXXSMP */ /* * The last thread is left attached to the process * So that the whole bundle gets recycled. Skip * all this stuff. */ if (p->p_numthreads > 1) { /* Reassign this thread's KSE. */ ke->ke_thread = NULL; td->td_kse = NULL; ke->ke_state = KES_UNQUEUED; if (ke->ke_bound == td) ke->ke_bound = NULL; kse_reassign(ke); /* Unlink this thread from its proc. and the kseg */ TAILQ_REMOVE(&p->p_threads, td, td_plist); p->p_numthreads--; TAILQ_REMOVE(&kg->kg_threads, td, td_kglist); kg->kg_numthreads--; /* * The test below is NOT true if we are the * sole exiting thread. P_STOPPED_SNGL is unset * in exit1() after it is the only survivor. */ if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { if (p->p_numthreads == p->p_suspcount) { thread_unsuspend_one(p->p_singlethread); } } PROC_UNLOCK(p); td->td_state = TDS_INACTIVE; td->td_proc = NULL; td->td_ksegrp = NULL; td->td_last_kse = NULL; ke->ke_tdspare = td; } else { PROC_UNLOCK(p); } cpu_throw(); /* NOTREACHED */ } /* * Link a thread to a process. * set up anything that needs to be initialized for it to * be used by the process. * * Note that we do not link to the proc's ucred here. * The thread is linked as if running but no KSE assigned. */ void thread_link(struct thread *td, struct ksegrp *kg) { struct proc *p; p = kg->kg_proc; td->td_state = TDS_INACTIVE; td->td_proc = p; td->td_ksegrp = kg; td->td_last_kse = NULL; LIST_INIT(&td->td_contested); callout_init(&td->td_slpcallout, 1); TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist); p->p_numthreads++; kg->kg_numthreads++; if (oiks_debug && p->p_numthreads > max_threads_per_proc) { printf("OIKS %d\n", p->p_numthreads); if (oiks_debug > 1) Debugger("OIKS"); } td->td_kse = NULL; } /* * Create a thread and schedule it for upcall on the KSE given. */ struct thread * thread_schedule_upcall(struct thread *td, struct kse *ke) { struct thread *td2; mtx_assert(&sched_lock, MA_OWNED); if (ke->ke_tdspare != NULL) { td2 = ke->ke_tdspare; ke->ke_tdspare = NULL; } else { mtx_unlock_spin(&sched_lock); td2 = thread_alloc(); mtx_lock_spin(&sched_lock); } CTR3(KTR_PROC, "thread_schedule_upcall: thread %p (pid %d, %s)", td, td->td_proc->p_pid, td->td_proc->p_comm); bzero(&td2->td_startzero, (unsigned)RANGEOF(struct thread, td_startzero, td_endzero)); bcopy(&td->td_startcopy, &td2->td_startcopy, (unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy)); thread_link(td2, ke->ke_ksegrp); cpu_set_upcall(td2, td->td_pcb); bcopy(td->td_frame, td2->td_frame, sizeof(struct trapframe)); /* * The user context for this thread is selected when we choose * a KSE and return to userland on it. All we need do here is * note that the thread exists in order to perform an upcall. * * Since selecting a KSE to perform the upcall involves locking * that KSE's context to our upcall, its best to wait until the * last possible moment before grabbing a KSE. We do this in * userret(). */ td2->td_ucred = crhold(td->td_ucred); td2->td_flags = TDF_UNBOUND|TDF_UPCALLING; TD_SET_CAN_RUN(td2); setrunqueue(td2); return (td2); } /* * Schedule an upcall to notify a KSE process recieved signals. * * XXX - Modifying a sigset_t like this is totally bogus. */ struct thread * signal_upcall(struct proc *p, int sig) { struct thread *td, *td2; struct kse *ke; sigset_t ss; int error; PROC_LOCK_ASSERT(p, MA_OWNED); td = FIRST_THREAD_IN_PROC(p); ke = td->td_kse; PROC_UNLOCK(p); error = copyin(&ke->ke_mailbox->km_sigscaught, &ss, sizeof(sigset_t)); PROC_LOCK(p); if (error) return (NULL); SIGADDSET(ss, sig); PROC_UNLOCK(p); error = copyout(&ss, &ke->ke_mailbox->km_sigscaught, sizeof(sigset_t)); PROC_LOCK(p); if (error) return (NULL); mtx_lock_spin(&sched_lock); td2 = thread_schedule_upcall(td, ke); mtx_unlock_spin(&sched_lock); return (td2); } /* * Consider whether or not an upcall should be made, and update the * TDF_UPCALLING flag appropriately. * * This function is called when the current thread had been bound to a user * thread that performed a syscall that blocked, and is now returning. * Got that? syscall -> msleep -> wakeup -> syscall_return -> us. * * This thread will be returned to the UTS in its mailbox as a completed * thread. We need to decide whether or not to perform an upcall now, * or simply queue the thread for later. * * XXXKSE Future enhancement: We could also return back to * the thread if we haven't had to do an upcall since then. * If the KSE's copy is == the thread's copy, and there are * no other completed threads. */ static int thread_consider_upcalling(struct thread *td) { struct proc *p; struct ksegrp *kg; int error; /* * Save the thread's context, and link it * into the KSEGRP's list of completed threads. */ error = thread_export_context(td); td->td_flags &= ~TDF_UNBOUND; td->td_mailbox = NULL; if (error) /* * Failing to do the KSE operation just defaults * back to synchonous operation, so just return from * the syscall. */ return (error); /* * Decide whether to perform an upcall now. */ /* Make sure there are no other threads waiting to run. */ p = td->td_proc; kg = td->td_ksegrp; PROC_LOCK(p); mtx_lock_spin(&sched_lock); /* bogus test, ok for testing though */ if (TAILQ_FIRST(&kg->kg_runq) && (TAILQ_LAST(&kg->kg_runq, threadqueue) != kg->kg_last_assigned)) { /* * Another thread in this KSEG needs to run. * Switch to it instead of performing an upcall, * abondoning this thread. Perform the upcall * later; discard this thread for now. * * XXXKSE - As for the other threads to run; * we COULD rush through all the threads * in this KSEG at this priority, or we * could throw the ball back into the court * and just run the highest prio kse available. * What is OUR priority? The priority of the highest * sycall waiting to be returned? * For now, just let another KSE run (easiest). */ thread_exit(); /* Abandon current thread. */ /* NOTREACHED */ } /* * Perform an upcall now. * * XXXKSE - Assumes we are going to userland, and not * nested in the kernel. */ td->td_flags |= TDF_UPCALLING; mtx_unlock_spin(&sched_lock); PROC_UNLOCK(p); return (0); } /* * The extra work we go through if we are a threaded process when we * return to userland. * * If we are a KSE process and returning to user mode, check for * extra work to do before we return (e.g. for more syscalls * to complete first). If we were in a critical section, we should * just return to let it finish. Same if we were in the UTS (in * which case the mailbox's context's busy indicator will be set). * The only traps we suport will have set the mailbox. * We will clear it here. */ int thread_userret(struct thread *td, struct trapframe *frame) { int error; int unbound; struct kse *ke; if (td->td_kse->ke_bound) { thread_export_context(td); PROC_LOCK(td->td_proc); mtx_lock_spin(&sched_lock); thread_exit(); } /* Make the thread bound from now on, but remember what it was. */ unbound = td->td_flags & TDF_UNBOUND; td->td_flags &= ~TDF_UNBOUND; /* * Ensure that we have a spare thread available. */ ke = td->td_kse; if (ke->ke_tdspare == NULL) { mtx_lock(&Giant); ke->ke_tdspare = thread_alloc(); mtx_unlock(&Giant); } /* * Originally bound threads need no additional work. */ if (unbound == 0) return (0); error = 0; /* * Decide whether or not we should perform an upcall now. */ if (((td->td_flags & TDF_UPCALLING) == 0) && unbound) { /* if we have other threads to run we will not return */ if ((error = thread_consider_upcalling(td))) return (error); /* coundn't go async , just go sync. */ } if (td->td_flags & TDF_UPCALLING) { /* * There is no more work to do and we are going to ride * this thead/KSE up to userland as an upcall. */ CTR3(KTR_PROC, "userret: upcall thread %p (pid %d, %s)", td, td->td_proc->p_pid, td->td_proc->p_comm); /* * Set user context to the UTS. */ cpu_set_upcall_kse(td, ke); /* * Put any completed mailboxes on this KSE's list. */ error = thread_link_mboxes(td->td_ksegrp, ke); if (error) goto bad; /* * Set state and mailbox. */ td->td_flags &= ~TDF_UPCALLING; #if 0 error = suword((caddr_t)ke->ke_mailbox + offsetof(struct kse_mailbox, km_curthread), 0); #else /* if user pointer arithmetic is ok in the kernel */ error = suword((caddr_t)&ke->ke_mailbox->km_curthread, 0); #endif if (error) goto bad; } /* * Stop any chance that we may be separated from * the KSE we are currently on. This is "biting the bullet", * we are committing to go to user space as as this KSE here. */ return (error); bad: /* * Things are going to be so screwed we should just kill the process. * how do we do that? */ panic ("thread_userret.. need to kill proc..... how?"); } /* * Enforce single-threading. * * Returns 1 if the caller must abort (another thread is waiting to * exit the process or similar). Process is locked! * Returns 0 when you are successfully the only thread running. * A process has successfully single threaded in the suspend mode when * There are no threads in user mode. Threads in the kernel must be * allowed to continue until they get to the user boundary. They may even * copy out their return values and data before suspending. They may however be * accellerated in reaching the user boundary as we will wake up * any sleeping threads that are interruptable. (PCATCH). */ int thread_single(int force_exit) { struct thread *td; struct thread *td2; struct proc *p; td = curthread; p = td->td_proc; PROC_LOCK_ASSERT(p, MA_OWNED); KASSERT((td != NULL), ("curthread is NULL")); if ((p->p_flag & P_KSES) == 0) return (0); /* Is someone already single threading? */ if (p->p_singlethread) return (1); if (force_exit == SINGLE_EXIT) p->p_flag |= P_SINGLE_EXIT; else p->p_flag &= ~P_SINGLE_EXIT; p->p_flag |= P_STOPPED_SINGLE; p->p_singlethread = td; while ((p->p_numthreads - p->p_suspcount) != 1) { mtx_lock_spin(&sched_lock); FOREACH_THREAD_IN_PROC(p, td2) { if (td2 == td) continue; if (TD_IS_INHIBITED(td2)) { if (TD_IS_SUSPENDED(td2)) { if (force_exit == SINGLE_EXIT) { thread_unsuspend_one(td2); } } if ( TD_IS_SLEEPING(td2)) { if (td2->td_flags & TDF_CVWAITQ) cv_waitq_remove(td2); else unsleep(td2); break; } if (TD_CAN_RUN(td2)) setrunqueue(td2); } } /* * Wake us up when everyone else has suspended. * In the mean time we suspend as well. */ thread_suspend_one(td); mtx_unlock(&Giant); PROC_UNLOCK(p); mi_switch(); mtx_unlock_spin(&sched_lock); mtx_lock(&Giant); PROC_LOCK(p); } return (0); } /* * Called in from locations that can safely check to see * whether we have to suspend or at least throttle for a * single-thread event (e.g. fork). * * Such locations include userret(). * If the "return_instead" argument is non zero, the thread must be able to * accept 0 (caller may continue), or 1 (caller must abort) as a result. * * The 'return_instead' argument tells the function if it may do a * thread_exit() or suspend, or whether the caller must abort and back * out instead. * * If the thread that set the single_threading request has set the * P_SINGLE_EXIT bit in the process flags then this call will never return * if 'return_instead' is false, but will exit. * * P_SINGLE_EXIT | return_instead == 0| return_instead != 0 *---------------+--------------------+--------------------- * 0 | returns 0 | returns 0 or 1 * | when ST ends | immediatly *---------------+--------------------+--------------------- * 1 | thread exits | returns 1 * | | immediatly * 0 = thread_exit() or suspension ok, * other = return error instead of stopping the thread. * * While a full suspension is under effect, even a single threading * thread would be suspended if it made this call (but it shouldn't). * This call should only be made from places where * thread_exit() would be safe as that may be the outcome unless * return_instead is set. */ int thread_suspend_check(int return_instead) { struct thread *td; struct proc *p; td = curthread; p = td->td_proc; PROC_LOCK_ASSERT(p, MA_OWNED); while (P_SHOULDSTOP(p)) { if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { KASSERT(p->p_singlethread != NULL, ("singlethread not set")); /* * The only suspension in action is a * single-threading. Single threader need not stop. * XXX Should be safe to access unlocked * as it can only be set to be true by us. */ if (p->p_singlethread == td) return (0); /* Exempt from stopping. */ } if (return_instead) return (1); /* * If the process is waiting for us to exit, * this thread should just suicide. * Assumes that P_SINGLE_EXIT implies P_STOPPED_SINGLE. */ if ((p->p_flag & P_SINGLE_EXIT) && (p->p_singlethread != td)) { mtx_lock_spin(&sched_lock); while (mtx_owned(&Giant)) mtx_unlock(&Giant); thread_exit(); } /* * When a thread suspends, it just * moves to the processes's suspend queue * and stays there. * * XXXKSE if TDF_BOUND is true * it will not release it's KSE which might * lead to deadlock if there are not enough KSEs * to complete all waiting threads. * Maybe be able to 'lend' it out again. * (lent kse's can not go back to userland?) * and can only be lent in STOPPED state. */ mtx_lock_spin(&sched_lock); if ((p->p_flag & P_STOPPED_SIG) && (p->p_suspcount+1 == p->p_numthreads)) { mtx_unlock_spin(&sched_lock); PROC_LOCK(p->p_pptr); if ((p->p_pptr->p_procsig->ps_flag & PS_NOCLDSTOP) == 0) { psignal(p->p_pptr, SIGCHLD); } PROC_UNLOCK(p->p_pptr); mtx_lock_spin(&sched_lock); } mtx_assert(&Giant, MA_NOTOWNED); thread_suspend_one(td); PROC_UNLOCK(p); if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { if (p->p_numthreads == p->p_suspcount) { thread_unsuspend_one(p->p_singlethread); } } p->p_stats->p_ru.ru_nivcsw++; mi_switch(); mtx_unlock_spin(&sched_lock); PROC_LOCK(p); } return (0); } void thread_suspend_one(struct thread *td) { struct proc *p = td->td_proc; mtx_assert(&sched_lock, MA_OWNED); p->p_suspcount++; TD_SET_SUSPENDED(td); TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); /* * Hack: If we are suspending but are on the sleep queue * then we are in msleep or the cv equivalent. We * want to look like we have two Inhibitors. */ if (TD_ON_SLEEPQ(td)) TD_SET_SLEEPING(td); } void thread_unsuspend_one(struct thread *td) { struct proc *p = td->td_proc; mtx_assert(&sched_lock, MA_OWNED); TAILQ_REMOVE(&p->p_suspended, td, td_runq); TD_CLR_SUSPENDED(td); p->p_suspcount--; setrunnable(td); } /* * Allow all threads blocked by single threading to continue running. */ void thread_unsuspend(struct proc *p) { struct thread *td; mtx_assert(&sched_lock, MA_OWNED); PROC_LOCK_ASSERT(p, MA_OWNED); if (!P_SHOULDSTOP(p)) { while (( td = TAILQ_FIRST(&p->p_suspended))) { thread_unsuspend_one(td); } } else if ((P_SHOULDSTOP(p) == P_STOPPED_SINGLE) && (p->p_numthreads == p->p_suspcount)) { /* * Stopping everything also did the job for the single * threading request. Now we've downgraded to single-threaded, * let it continue. */ thread_unsuspend_one(p->p_singlethread); } } void thread_single_end(void) { struct thread *td; struct proc *p; td = curthread; p = td->td_proc; PROC_LOCK_ASSERT(p, MA_OWNED); p->p_flag &= ~P_STOPPED_SINGLE; p->p_singlethread = NULL; /* * If there are other threads they mey now run, * unless of course there is a blanket 'stop order' * on the process. The single threader must be allowed * to continue however as this is a bad place to stop. */ if ((p->p_numthreads != 1) && (!P_SHOULDSTOP(p))) { mtx_lock_spin(&sched_lock); while (( td = TAILQ_FIRST(&p->p_suspended))) { thread_unsuspend_one(td); } mtx_unlock_spin(&sched_lock); } }