/* * 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 /* * Thread related storage. */ static uma_zone_t thread_zone; static int allocated_threads; static int active_threads; static int cached_threads; SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation"); SYSCTL_INT(_kern_threads, OID_AUTO, active, CTLFLAG_RD, &active_threads, 0, "Number of active threads in system."); SYSCTL_INT(_kern_threads, OID_AUTO, cached, CTLFLAG_RD, &cached_threads, 0, "Number of threads in thread cache."); SYSCTL_INT(_kern_threads, OID_AUTO, allocated, CTLFLAG_RD, &allocated_threads, 0, "Number of threads in zone."); 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"); #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; bzero(&td->td_startzero, (unsigned)RANGEOF(struct thread, td_startzero, td_endzero)); td->td_state = TDS_NEW; td->td_flags |= TDF_UNBOUND; #if 0 /* * Maybe move these here from process creation, but maybe not. * Moving them here takes them away from their "natural" place * in the fork process. */ /* XXX td_contested does not appear to be initialized for threads! */ LIST_INIT(&td->td_contested); callout_init(&td->td_slpcallout, 1); #endif cached_threads--; /* XXXSMP */ active_threads++; /* XXXSMP */ } /* * 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_SLP: case TDS_MTX: 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_UNQUEUED: case TDS_NEW: case TDS_RUNNING: case TDS_SURPLUS: break; default: panic("bad thread state"); /* NOTREACHED */ } #endif /* Update counters. */ active_threads--; /* XXXSMP */ cached_threads++; /* XXXSMP */ } /* * 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; pmap_new_thread(td); cpu_thread_setup(td); cached_threads++; /* XXXSMP */ allocated_threads++; /* XXXSMP */ } /* * 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); cached_threads--; /* XXXSMP */ allocated_threads--; /* XXXSMP */ } /* * Initialize global thread allocation resources. */ void threadinit(void) { thread_zone = uma_zcreate("THREAD", sizeof (struct thread), thread_ctor, thread_dtor, thread_init, thread_fini, UMA_ALIGN_CACHE, 0); } /* * Stash an embarasingly esxtra 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 any zombie threads for this Processor. */ 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 thread. */ struct thread * thread_alloc(void) { thread_reap(); /* check if any zombies to get */ return (uma_zalloc(thread_zone, M_WAITOK)); } /* * Deallocate a thread. */ void thread_free(struct thread *td) { uma_zfree(thread_zone, td); } /* * Store the thread context in the UTS's mailbox. */ int thread_export_context(struct thread *td) { struct kse *ke; uintptr_t td2_mbx; void *addr1; void *addr2; int error; /* Export the register contents. */ error = cpu_export_context(td); ke = td->td_kse; addr1 = (caddr_t)ke->ke_mailbox + offsetof(struct kse_mailbox, kmbx_completed_threads); addr2 = (caddr_t)td->td_mailbox + offsetof(struct thread_mailbox , next_completed); /* Then link it into it's KSE's list of completed threads. */ if (!error) { error = td2_mbx = fuword(addr1); if (error == -1) error = EFAULT; else error = 0; } if (!error) error = suword(addr2, td2_mbx); if (!error) error = suword(addr1, (u_long)td->td_mailbox); if (error == -1) error = EFAULT; return (error); } /* * 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); 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 */ /* Reassign this thread's KSE. */ if (ke != NULL) { ke->ke_thread = NULL; td->td_kse = NULL; ke->ke_state = KES_UNQUEUED; kse_reassign(ke); } /* Unlink this thread from its proc. and the kseg */ if (p != NULL) { TAILQ_REMOVE(&p->p_threads, td, td_plist); p->p_numthreads--; if (kg != NULL) { 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_SNGL) { if (p->p_numthreads == p->p_suspcount) { TAILQ_REMOVE(&p->p_suspended, p->p_singlethread, td_runq); setrunqueue(p->p_singlethread); p->p_suspcount--; } } } td->td_state = TDS_SURPLUS; td->td_proc = NULL; td->td_ksegrp = NULL; td->td_last_kse = NULL; ke->ke_tdspare = td; PROC_UNLOCK(p); cpu_throw(); /* NOTREACHED */ } /* * Link a thread to a 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_NEW; td->td_proc = p; td->td_ksegrp = kg; td->td_last_kse = NULL; 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 > 4) { printf("OIKS %d\n", p->p_numthreads); if (oiks_debug > 1) Debugger("OIKS"); } td->td_critnest = 0; td->td_kse = NULL; } /* * Set up the upcall pcb in either a given thread or a new one * if none given. Use the upcall for the given KSE * XXXKSE possibly fix cpu_set_upcall() to not need td->td_kse set. */ 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); thread_link(td2, ke->ke_ksegrp); cpu_set_upcall(td2, ke->ke_pcb); td2->td_ucred = crhold(td->td_ucred); td2->td_flags = TDF_UNBOUND|TDF_UPCALLING; td2->td_priority = td->td_priority; setrunqueue(td2); return (td2); } /* * 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 we will have no thread mailbox registered). The only * traps we suport will have set the mailbox. We will clear it here. */ int thread_userret(struct proc *p, struct ksegrp *kg, struct kse *ke, struct thread *td, struct trapframe *frame) { int error = 0; if (ke->ke_tdspare == NULL) { ke->ke_tdspare = thread_alloc(); } if (td->td_flags & TDF_UNBOUND) { /* * Are we returning from a thread that had a mailbox? * * XXX Maybe this should be in a separate function. */ if (((td->td_flags & TDF_UPCALLING) == 0) && td->td_mailbox) { /* * [XXXKSE Future enhancement] * We could also go straight back to the syscall * if we never had to do an upcall since then. * If the KSE's copy is == the thread's copy.. * AND there are no other completed threads. */ /* * We will go back as an upcall or go do another thread. * Either way we need to save the context back to * the user thread mailbox. * So the UTS can restart it later. */ error = thread_export_context(td); td->td_mailbox = NULL; if (error) { /* * Failing to do the KSE * operation just defaults operation * back to synchonous operation. */ goto cont; } if (TAILQ_FIRST(&kg->kg_runq)) { /* * Uh-oh.. don't return to the user. * Instead, switch to the thread that * needs to run. The question is: * What do we do with the thread we have now? * We have put the completion block * on the kse mailbox. If we had more energy, * we could lazily do so, assuming someone * else might get to userland earlier * and deliver it earlier than we could. * To do that we could save it off the KSEG. * An upcalling KSE would 'reap' all completed * threads. * Being in a hurry, we'll do nothing and * leave it on the current KSE for now. * * 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). */ PROC_LOCK(p); mtx_lock_spin(&sched_lock); thread_exit(); /* Abandon current thread. */ /* NOTREACHED */ } else { /* if (number of returning syscalls = 1) */ /* * Swap our frame for the upcall frame. * * XXXKSE Assumes we are going to user land * and not nested in the kernel */ td->td_flags |= TDF_UPCALLING; } } /* * This is NOT just an 'else' clause for the above test... */ if (td->td_flags & TDF_UPCALLING) { CTR3(KTR_PROC, "userret: upcall thread %p (pid %d, %s)", td, p->p_pid, p->p_comm); /* * Make sure that it has the correct frame loaded. * While we know that we are on the same KSEGRP * as we were created on, we could very easily * have come in on another KSE. We therefore need * to do the copy of the frame after the last * possible switch() (the one above). */ bcopy(ke->ke_frame, frame, sizeof(struct trapframe)); /* * Decide what we are sending to the user * upcall sets one argument. The address of the mbox. */ cpu_set_args(td, ke); /* * There is no more work to do and we are going to ride * this thead/KSE up to userland. Make sure the user's * pointer to the thread mailbox is cleared before we * re-enter the kernel next time for any reason.. * We might as well do it here. */ td->td_flags &= ~TDF_UPCALLING; /* Hmmmm. */ error = suword((caddr_t)td->td_kse->ke_mailbox + offsetof(struct kse_mailbox, kmbx_current_thread), 0); } /* * 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. */ cont: td->td_flags &= ~TDF_UNBOUND; } return (error); } /* * 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); if (p->p_singlethread) { /* * Someone is already single threading! */ return (1); } if (force_exit == SNGLE_EXIT) p->p_flag |= P_SINGLE_EXIT; else p->p_flag &= ~P_SINGLE_EXIT; p->p_flag |= P_STOPPED_SNGL; p->p_singlethread = td; while ((p->p_numthreads - p->p_suspcount) != 1) { FOREACH_THREAD_IN_PROC(p, td2) { if (td2 == td) continue; switch(td2->td_state) { case TDS_SUSPENDED: if (force_exit == SNGLE_EXIT) { TAILQ_REMOVE(&p->p_suspended, td, td_runq); setrunqueue(td); /* Should suicide. */ } case TDS_SLP: if (td2->td_flags & TDF_CVWAITQ) { cv_abort(td2); } else { abortsleep(td2); } break; /* etc. XXXKSE */ default: ; } } /* * XXXKSE-- idea * It's possible that we can just wake up when * there are no runnable KSEs, because that would * indicate that only this thread is runnable and * there are no running KSEs in userland. * -- * Wake us up when everyone else has suspended. * (or died) */ mtx_lock_spin(&sched_lock); TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); td->td_state = TDS_SUSPENDED; p->p_suspcount++; 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 = curthread; struct proc *p = td->td_proc; td = curthread; p = td->td_proc; PROC_LOCK_ASSERT(p, MA_OWNED); while (P_SHOULDSTOP(p)) { if (P_SHOULDSTOP(p) == P_STOPPED_SNGL) { KASSERT(p->p_singlethread != NULL, ("singlethread not set")); /* * The only suspension in action is * a single-threading. Treat it ever * so slightly different if it is * in a special situation. */ 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_SNGL. */ 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_assert(&Giant, MA_NOTOWNED); mtx_lock_spin(&sched_lock); p->p_suspcount++; td->td_state = TDS_SUSPENDED; TAILQ_INSERT_TAIL(&p->p_suspended, td, td_runq); PROC_UNLOCK(p); mi_switch(); mtx_unlock_spin(&sched_lock); PROC_LOCK(p); } return (0); } /* * Allow all threads blocked by single threading to continue running. */ void thread_unsuspend(struct proc *p) { struct thread *td; PROC_LOCK_ASSERT(p, MA_OWNED); if (!P_SHOULDSTOP(p)) { while (( td = TAILQ_FIRST(&p->p_suspended))) { TAILQ_REMOVE(&p->p_suspended, td, td_runq); p->p_suspcount--; setrunqueue(td); } } else if ((P_SHOULDSTOP(p) == P_STOPPED_SNGL) && (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. */ TAILQ_REMOVE(&p->p_suspended, p->p_singlethread, td_runq); p->p_suspcount--; setrunqueue(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_SNGL; p->p_singlethread = NULL; thread_unsuspend(p); }