/* * 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. */ #include __FBSDID("$FreeBSD$"); #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 thread_debug = 0; SYSCTL_INT(_kern_threads, OID_AUTO, debug, CTLFLAG_RW, &thread_debug, 0, "thread debug"); int max_threads_per_proc = 1500; SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW, &max_threads_per_proc, 0, "Limit on threads per proc"); int max_groups_per_proc = 500; SYSCTL_INT(_kern_threads, OID_AUTO, max_groups_per_proc, CTLFLAG_RW, &max_groups_per_proc, 0, "Limit on thread groups per proc"); int max_threads_hits; SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD, &max_threads_hits, 0, ""); int virtual_cpu; #define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start)) TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads); TAILQ_HEAD(, kse) zombie_kses = TAILQ_HEAD_INITIALIZER(zombie_kses); TAILQ_HEAD(, ksegrp) zombie_ksegrps = TAILQ_HEAD_INITIALIZER(zombie_ksegrps); struct mtx kse_zombie_lock; MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN); void kse_purge(struct proc *p, struct thread *td); void kse_purge_group(struct thread *td); /* move to proc.h */ extern void kseinit(void); extern void kse_GC(void); static int sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS) { int error, new_val; int def_val; def_val = mp_ncpus; if (virtual_cpu == 0) new_val = def_val; else new_val = virtual_cpu; error = sysctl_handle_int(oidp, &new_val, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (new_val < 0) return (EINVAL); virtual_cpu = new_val; return (0); } /* DEBUG ONLY */ SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW, 0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I", "debug virtual cpus"); /* * Thread ID allocator. The allocator keeps track of assigned IDs by * using a bitmap. The bitmap is created in parts. The parts are linked * together. */ typedef u_long tid_bitmap_word; #define TID_IDS_PER_PART 1024 #define TID_IDS_PER_IDX (sizeof(tid_bitmap_word) << 3) #define TID_BITMAP_SIZE (TID_IDS_PER_PART / TID_IDS_PER_IDX) #define TID_MIN (PID_MAX + 1) struct tid_bitmap_part { STAILQ_ENTRY(tid_bitmap_part) bmp_next; tid_bitmap_word bmp_bitmap[TID_BITMAP_SIZE]; int bmp_base; int bmp_free; }; static STAILQ_HEAD(, tid_bitmap_part) tid_bitmap = STAILQ_HEAD_INITIALIZER(tid_bitmap); static uma_zone_t tid_zone; struct mtx tid_lock; MTX_SYSINIT(tid_lock, &tid_lock, "TID lock", MTX_DEF); /* * Prepare a thread for use. */ static void thread_ctor(void *mem, int size, void *arg) { struct thread *td; td = (struct thread *)mem; td->td_tid = 0; td->td_state = TDS_INACTIVE; td->td_oncpu = NOCPU; /* * Note that td_critnest begins life as 1 because the thread is not * running and is thereby implicitly waiting to be on the receiving * end of a context switch. A context switch must occur inside a * critical section, and in fact, includes hand-off of the sched_lock. * After a context switch to a newly created thread, it will release * sched_lock for the first time, and its td_critnest will hit 0 for * the first time. This happens on the far end of a context switch, * and when it context switches away from itself, it will in fact go * back into a critical section, and hand off the sched lock to the * next thread. */ td->td_critnest = 1; } /* * Reclaim a thread after use. */ static void thread_dtor(void *mem, int size, void *arg) { struct thread *td; struct tid_bitmap_part *bmp; int bit, idx, tid; td = (struct thread *)mem; if (td->td_tid > PID_MAX) { STAILQ_FOREACH(bmp, &tid_bitmap, bmp_next) { if (td->td_tid >= bmp->bmp_base && td->td_tid < bmp->bmp_base + TID_IDS_PER_PART) break; } KASSERT(bmp != NULL, ("No TID bitmap?")); mtx_lock(&tid_lock); tid = td->td_tid - bmp->bmp_base; idx = tid / TID_IDS_PER_IDX; bit = 1UL << (tid % TID_IDS_PER_IDX); bmp->bmp_bitmap[idx] |= bit; bmp->bmp_free++; mtx_unlock(&tid_lock); } #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; td = (struct thread *)mem; vm_thread_new(td, 0); cpu_thread_setup(td); td->td_sleepqueue = sleepq_alloc(); td->td_turnstile = turnstile_alloc(); td->td_sched = (struct td_sched *)&td[1]; } /* * Tear down type-stable parts of a thread (just before being discarded). */ static void thread_fini(void *mem, int size) { struct thread *td; td = (struct thread *)mem; turnstile_free(td->td_turnstile); sleepq_free(td->td_sleepqueue); vm_thread_dispose(td); } /* * Initialize type-stable parts of a kse (when newly created). */ static void kse_init(void *mem, int size) { struct kse *ke; ke = (struct kse *)mem; ke->ke_sched = (struct ke_sched *)&ke[1]; } /* * Initialize type-stable parts of a ksegrp (when newly created). */ static void ksegrp_init(void *mem, int size) { struct ksegrp *kg; kg = (struct ksegrp *)mem; kg->kg_sched = (struct kg_sched *)&kg[1]; } /* * KSE is linked into kse group. */ void kse_link(struct kse *ke, struct ksegrp *kg) { struct proc *p = kg->kg_proc; TAILQ_INSERT_HEAD(&kg->kg_kseq, ke, ke_kglist); kg->kg_kses++; ke->ke_state = KES_UNQUEUED; ke->ke_proc = p; ke->ke_ksegrp = kg; ke->ke_thread = NULL; ke->ke_oncpu = NOCPU; ke->ke_flags = 0; } void kse_unlink(struct kse *ke) { struct ksegrp *kg; mtx_assert(&sched_lock, MA_OWNED); kg = ke->ke_ksegrp; TAILQ_REMOVE(&kg->kg_kseq, ke, ke_kglist); if (ke->ke_state == KES_IDLE) { TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist); kg->kg_idle_kses--; } --kg->kg_kses; /* * Aggregate stats from the KSE */ kse_stash(ke); } void ksegrp_link(struct ksegrp *kg, struct proc *p) { TAILQ_INIT(&kg->kg_threads); TAILQ_INIT(&kg->kg_runq); /* links with td_runq */ TAILQ_INIT(&kg->kg_slpq); /* links with td_runq */ TAILQ_INIT(&kg->kg_kseq); /* all kses in ksegrp */ TAILQ_INIT(&kg->kg_iq); /* all idle kses in ksegrp */ TAILQ_INIT(&kg->kg_upcalls); /* all upcall structure in ksegrp */ kg->kg_proc = p; /* * the following counters are in the -zero- section * and may not need clearing */ kg->kg_numthreads = 0; kg->kg_runnable = 0; kg->kg_kses = 0; kg->kg_runq_kses = 0; /* XXXKSE change name */ kg->kg_idle_kses = 0; kg->kg_numupcalls = 0; /* link it in now that it's consistent */ p->p_numksegrps++; TAILQ_INSERT_HEAD(&p->p_ksegrps, kg, kg_ksegrp); } void ksegrp_unlink(struct ksegrp *kg) { struct proc *p; mtx_assert(&sched_lock, MA_OWNED); KASSERT((kg->kg_numthreads == 0), ("ksegrp_unlink: residual threads")); KASSERT((kg->kg_kses == 0), ("ksegrp_unlink: residual kses")); KASSERT((kg->kg_numupcalls == 0), ("ksegrp_unlink: residual upcalls")); p = kg->kg_proc; TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp); p->p_numksegrps--; /* * Aggregate stats from the KSE */ ksegrp_stash(kg); } /* * For a newly created process, * link up all the structures and its initial threads etc. */ void proc_linkup(struct proc *p, struct ksegrp *kg, struct kse *ke, struct thread *td) { TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */ TAILQ_INIT(&p->p_threads); /* all threads in proc */ TAILQ_INIT(&p->p_suspended); /* Threads suspended */ p->p_numksegrps = 0; p->p_numthreads = 0; ksegrp_link(kg, p); kse_link(ke, kg); thread_link(td, kg); } /* * Initialize global thread allocation resources. */ void threadinit(void) { thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(), thread_ctor, thread_dtor, thread_init, thread_fini, UMA_ALIGN_CACHE, 0); tid_zone = uma_zcreate("TID", sizeof(struct tid_bitmap_part), NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0); ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(), NULL, NULL, ksegrp_init, NULL, UMA_ALIGN_CACHE, 0); kse_zone = uma_zcreate("KSE", sched_sizeof_kse(), NULL, NULL, kse_init, NULL, UMA_ALIGN_CACHE, 0); kseinit(); } /* * Stash an embarasingly extra thread into the zombie thread queue. */ void thread_stash(struct thread *td) { mtx_lock_spin(&kse_zombie_lock); TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq); mtx_unlock_spin(&kse_zombie_lock); } /* * Stash an embarasingly extra kse into the zombie kse queue. */ void kse_stash(struct kse *ke) { mtx_lock_spin(&kse_zombie_lock); TAILQ_INSERT_HEAD(&zombie_kses, ke, ke_procq); mtx_unlock_spin(&kse_zombie_lock); } /* * Stash an embarasingly extra ksegrp into the zombie ksegrp queue. */ void ksegrp_stash(struct ksegrp *kg) { mtx_lock_spin(&kse_zombie_lock); TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp); mtx_unlock_spin(&kse_zombie_lock); } /* * Reap zombie kse resource. */ void thread_reap(void) { struct thread *td_first, *td_next; struct kse *ke_first, *ke_next; struct ksegrp *kg_first, * kg_next; /* * 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)) || (!TAILQ_EMPTY(&zombie_kses)) || (!TAILQ_EMPTY(&zombie_ksegrps))) { mtx_lock_spin(&kse_zombie_lock); td_first = TAILQ_FIRST(&zombie_threads); ke_first = TAILQ_FIRST(&zombie_kses); kg_first = TAILQ_FIRST(&zombie_ksegrps); if (td_first) TAILQ_INIT(&zombie_threads); if (ke_first) TAILQ_INIT(&zombie_kses); if (kg_first) TAILQ_INIT(&zombie_ksegrps); mtx_unlock_spin(&kse_zombie_lock); while (td_first) { td_next = TAILQ_NEXT(td_first, td_runq); if (td_first->td_ucred) crfree(td_first->td_ucred); thread_free(td_first); td_first = td_next; } while (ke_first) { ke_next = TAILQ_NEXT(ke_first, ke_procq); kse_free(ke_first); ke_first = ke_next; } while (kg_first) { kg_next = TAILQ_NEXT(kg_first, kg_ksegrp); ksegrp_free(kg_first); kg_first = kg_next; } } kse_GC(); } /* * 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) { cpu_thread_clean(td); uma_zfree(thread_zone, td); } /* * Assign a thread ID. */ int thread_new_tid(void) { struct tid_bitmap_part *bmp, *new; int bit, idx, tid; mtx_lock(&tid_lock); STAILQ_FOREACH(bmp, &tid_bitmap, bmp_next) { if (bmp->bmp_free) break; } /* Create a new bitmap if we run out of free bits. */ if (bmp == NULL) { mtx_unlock(&tid_lock); new = uma_zalloc(tid_zone, M_WAITOK); mtx_lock(&tid_lock); bmp = STAILQ_LAST(&tid_bitmap, tid_bitmap_part, bmp_next); if (bmp == NULL || bmp->bmp_free < TID_IDS_PER_PART/2) { /* 1=free, 0=assigned. This way we can use ffsl(). */ memset(new->bmp_bitmap, ~0U, sizeof(new->bmp_bitmap)); new->bmp_base = (bmp == NULL) ? TID_MIN : bmp->bmp_base + TID_IDS_PER_PART; new->bmp_free = TID_IDS_PER_PART; STAILQ_INSERT_TAIL(&tid_bitmap, new, bmp_next); bmp = new; new = NULL; } } else new = NULL; /* We have a bitmap with available IDs. */ idx = 0; while (idx < TID_BITMAP_SIZE && bmp->bmp_bitmap[idx] == 0UL) idx++; bit = ffsl(bmp->bmp_bitmap[idx]) - 1; tid = bmp->bmp_base + idx * TID_IDS_PER_IDX + bit; bmp->bmp_bitmap[idx] &= ~(1UL << bit); bmp->bmp_free--; mtx_unlock(&tid_lock); if (new != NULL) uma_zfree(tid_zone, new); return (tid); } /* * Discard the current thread and exit from its context. * Always called with scheduler locked. * * Because we can't free a thread while we're operating under its context, * push the current thread into our CPU's deadthread holder. This means * we needn't worry about someone else grabbing our context before we * do a cpu_throw(). This may not be needed now as we are under schedlock. * Maybe we can just do a thread_stash() as thr_exit1 does. */ /* XXX * libthr expects its thread exit to return for the last * thread, meaning that the program is back to non-threaded * mode I guess. Because we do this (cpu_throw) unconditionally * here, they have their own version of it. (thr_exit1()) * that doesn't do it all if this was the last thread. * It is also called from thread_suspend_check(). * Of course in the end, they end up coming here through exit1 * anyhow.. After fixing 'thr' to play by the rules we should be able * to merge these two functions together. */ 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); mtx_assert(&Giant, MA_NOTOWNED); if (td->td_standin != NULL) { thread_stash(td->td_standin); td->td_standin = 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) { thread_unlink(td); if (p->p_maxthrwaits) wakeup(&p->p_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); } } /* * Because each upcall structure has an owner thread, * owner thread exits only when process is in exiting * state, so upcall to userland is no longer needed, * deleting upcall structure is safe here. * So when all threads in a group is exited, all upcalls * in the group should be automatically freed. */ if (td->td_upcall) upcall_remove(td); sched_exit_thread(FIRST_THREAD_IN_PROC(p), td); sched_exit_kse(FIRST_KSE_IN_PROC(p), ke); ke->ke_state = KES_UNQUEUED; ke->ke_thread = NULL; /* * Decide what to do with the KSE attached to this thread. */ if (ke->ke_flags & KEF_EXIT) { kse_unlink(ke); if (kg->kg_kses == 0) { sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), kg); ksegrp_unlink(kg); } } else kse_reassign(ke); PROC_UNLOCK(p); td->td_kse = NULL; td->td_state = TDS_INACTIVE; #if 0 td->td_proc = NULL; #endif td->td_ksegrp = NULL; td->td_last_kse = NULL; PCPU_SET(deadthread, td); } else { PROC_UNLOCK(p); } /* XXX Shouldn't cpu_throw() here. */ mtx_assert(&sched_lock, MA_OWNED); cpu_throw(td, choosethread()); panic("I'm a teapot!"); /* NOTREACHED */ } /* * Do any thread specific cleanups that may be needed in wait() * called with Giant, proc and schedlock not held. */ void thread_wait(struct proc *p) { struct thread *td; mtx_assert(&Giant, MA_NOTOWNED); KASSERT((p->p_numthreads == 1), ("Multiple threads in wait1()")); KASSERT((p->p_numksegrps == 1), ("Multiple ksegrps in wait1()")); FOREACH_THREAD_IN_PROC(p, td) { if (td->td_standin != NULL) { thread_free(td->td_standin); td->td_standin = NULL; } cpu_thread_clean(td); } thread_reap(); /* check for zombie threads etc. */ } /* * 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; td->td_flags = 0; td->td_kflags = 0; td->td_kse = NULL; LIST_INIT(&td->td_contested); callout_init(&td->td_slpcallout, CALLOUT_MPSAFE); TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist); TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist); p->p_numthreads++; kg->kg_numthreads++; } void thread_unlink(struct thread *td) { struct proc *p = td->td_proc; struct ksegrp *kg = td->td_ksegrp; mtx_assert(&sched_lock, MA_OWNED); TAILQ_REMOVE(&p->p_threads, td, td_plist); p->p_numthreads--; TAILQ_REMOVE(&kg->kg_threads, td, td_kglist); kg->kg_numthreads--; /* could clear a few other things here */ } /* * Purge a ksegrp resource. When a ksegrp is preparing to * exit, it calls this function. */ void kse_purge_group(struct thread *td) { struct ksegrp *kg; struct kse *ke; kg = td->td_ksegrp; KASSERT(kg->kg_numthreads == 1, ("%s: bad thread number", __func__)); while ((ke = TAILQ_FIRST(&kg->kg_iq)) != NULL) { KASSERT(ke->ke_state == KES_IDLE, ("%s: wrong idle KSE state", __func__)); kse_unlink(ke); } KASSERT((kg->kg_kses == 1), ("%s: ksegrp still has %d KSEs", __func__, kg->kg_kses)); KASSERT((kg->kg_numupcalls == 0), ("%s: ksegrp still has %d upcall datas", __func__, kg->kg_numupcalls)); } /* * Purge a process's KSE resource. When a process is preparing to * exit, it calls kse_purge to release any extra KSE resources in * the process. */ void kse_purge(struct proc *p, struct thread *td) { struct ksegrp *kg; struct kse *ke; KASSERT(p->p_numthreads == 1, ("bad thread number")); while ((kg = TAILQ_FIRST(&p->p_ksegrps)) != NULL) { TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp); p->p_numksegrps--; /* * There is no ownership for KSE, after all threads * in the group exited, it is possible that some KSEs * were left in idle queue, gc them now. */ while ((ke = TAILQ_FIRST(&kg->kg_iq)) != NULL) { KASSERT(ke->ke_state == KES_IDLE, ("%s: wrong idle KSE state", __func__)); TAILQ_REMOVE(&kg->kg_iq, ke, ke_kgrlist); kg->kg_idle_kses--; TAILQ_REMOVE(&kg->kg_kseq, ke, ke_kglist); kg->kg_kses--; kse_stash(ke); } KASSERT(((kg->kg_kses == 0) && (kg != td->td_ksegrp)) || ((kg->kg_kses == 1) && (kg == td->td_ksegrp)), ("ksegrp has wrong kg_kses: %d", kg->kg_kses)); KASSERT((kg->kg_numupcalls == 0), ("%s: ksegrp still has %d upcall datas", __func__, kg->kg_numupcalls)); if (kg != td->td_ksegrp) ksegrp_stash(kg); } TAILQ_INSERT_HEAD(&p->p_ksegrps, td->td_ksegrp, kg_ksegrp); p->p_numksegrps++; } /* * 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; int remaining; td = curthread; p = td->td_proc; mtx_assert(&Giant, MA_NOTOWNED); PROC_LOCK_ASSERT(p, MA_OWNED); KASSERT((td != NULL), ("curthread is NULL")); if ((p->p_flag & P_SA) == 0 && p->p_numthreads == 1) 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; mtx_lock_spin(&sched_lock); p->p_singlethread = td; if (force_exit == SINGLE_EXIT) remaining = p->p_numthreads; else remaining = p->p_numthreads - p->p_suspcount; while (remaining != 1) { FOREACH_THREAD_IN_PROC(p, td2) { if (td2 == td) continue; td2->td_flags |= TDF_ASTPENDING; if (TD_IS_INHIBITED(td2)) { if (force_exit == SINGLE_EXIT) { if (TD_IS_SUSPENDED(td2)) { thread_unsuspend_one(td2); } if (TD_ON_SLEEPQ(td2) && (td2->td_flags & TDF_SINTR)) { sleepq_abort(td2); } } else { if (TD_IS_SUSPENDED(td2)) continue; /* * maybe other inhibitted states too? * XXXKSE Is it totally safe to * suspend a non-interruptable thread? */ if (td2->td_inhibitors & (TDI_SLEEPING | TDI_SWAPPED)) thread_suspend_one(td2); } } } if (force_exit == SINGLE_EXIT) remaining = p->p_numthreads; else remaining = p->p_numthreads - p->p_suspcount; /* * Maybe we suspended some threads.. was it enough? */ if (remaining == 1) break; /* * Wake us up when everyone else has suspended. * In the mean time we suspend as well. */ thread_suspend_one(td); PROC_UNLOCK(p); mi_switch(SW_VOL); mtx_unlock_spin(&sched_lock); PROC_LOCK(p); mtx_lock_spin(&sched_lock); if (force_exit == SINGLE_EXIT) remaining = p->p_numthreads; else remaining = p->p_numthreads - p->p_suspcount; } if (force_exit == SINGLE_EXIT) { if (td->td_upcall) upcall_remove(td); kse_purge(p, td); } mtx_unlock_spin(&sched_lock); 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; mtx_assert(&Giant, MA_NOTOWNED); 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); mtx_lock_spin(&sched_lock); thread_stopped(p); /* * 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)) { if (p->p_flag & P_SA) thread_exit(); else thr_exit1(); } /* * When a thread suspends, it just * moves to the processes's suspend queue * and stays there. */ thread_suspend_one(td); if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) { if (p->p_numthreads == p->p_suspcount) { thread_unsuspend_one(p->p_singlethread); } } PROC_UNLOCK(p); mi_switch(SW_INVOL); 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); PROC_LOCK_ASSERT(p, MA_OWNED); KASSERT(!TD_IS_SUSPENDED(td), ("already suspended")); 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. * May already be set.. doesn't matter. */ 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); PROC_LOCK_ASSERT(p, 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_SINGLE_EXIT); mtx_lock_spin(&sched_lock); 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))) { while (( td = TAILQ_FIRST(&p->p_suspended))) { thread_unsuspend_one(td); } } mtx_unlock_spin(&sched_lock); }