1004 lines
25 KiB
C
1004 lines
25 KiB
C
/*
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* Copyright (C) 2001 Julian Elischer <julian@freebsd.org>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice(s), this list of conditions and the following disclaimer as
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* the first lines of this file unmodified other than the possible
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* addition of one or more copyright notices.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice(s), this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sysctl.h>
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#include <sys/filedesc.h>
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#include <sys/tty.h>
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#include <sys/signalvar.h>
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#include <sys/sx.h>
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#include <sys/user.h>
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#include <sys/jail.h>
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#include <sys/kse.h>
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#include <sys/ktr.h>
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#include <sys/ucontext.h>
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#include <vm/vm.h>
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#include <vm/vm_object.h>
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#include <vm/pmap.h>
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#include <vm/uma.h>
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#include <vm/vm_map.h>
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#include <machine/frame.h>
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/*
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* KSEGRP related storage.
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*/
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static uma_zone_t ksegrp_zone;
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static uma_zone_t kse_zone;
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static uma_zone_t thread_zone;
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/* DEBUG ONLY */
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SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0, "thread allocation");
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static int oiks_debug = 1; /* 0 disable, 1 printf, 2 enter debugger */
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SYSCTL_INT(_kern_threads, OID_AUTO, oiks, CTLFLAG_RW,
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&oiks_debug, 0, "OIKS thread debug");
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static int max_threads_per_proc = 6;
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SYSCTL_INT(_kern_threads, OID_AUTO, max_per_proc, CTLFLAG_RW,
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&max_threads_per_proc, 0, "Limit on threads per proc");
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#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
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struct threadqueue zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
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struct mtx zombie_thread_lock;
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MTX_SYSINIT(zombie_thread_lock, &zombie_thread_lock,
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"zombie_thread_lock", MTX_SPIN);
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/*
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* Pepare a thread for use.
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*/
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static void
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thread_ctor(void *mem, int size, void *arg)
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{
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struct thread *td;
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KASSERT((size == sizeof(struct thread)),
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("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
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td = (struct thread *)mem;
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td->td_state = TDS_INACTIVE;
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td->td_flags |= TDF_UNBOUND;
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}
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/*
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* Reclaim a thread after use.
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*/
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static void
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thread_dtor(void *mem, int size, void *arg)
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{
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struct thread *td;
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KASSERT((size == sizeof(struct thread)),
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("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
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td = (struct thread *)mem;
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#ifdef INVARIANTS
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/* Verify that this thread is in a safe state to free. */
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switch (td->td_state) {
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case TDS_INHIBITED:
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case TDS_RUNNING:
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case TDS_CAN_RUN:
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case TDS_RUNQ:
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/*
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* We must never unlink a thread that is in one of
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* these states, because it is currently active.
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*/
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panic("bad state for thread unlinking");
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/* NOTREACHED */
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case TDS_INACTIVE:
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break;
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default:
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panic("bad thread state");
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/* NOTREACHED */
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}
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#endif
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}
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/*
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* Initialize type-stable parts of a thread (when newly created).
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*/
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static void
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thread_init(void *mem, int size)
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{
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struct thread *td;
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KASSERT((size == sizeof(struct thread)),
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("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
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td = (struct thread *)mem;
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mtx_lock(&Giant);
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pmap_new_thread(td);
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mtx_unlock(&Giant);
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cpu_thread_setup(td);
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}
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/*
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* Tear down type-stable parts of a thread (just before being discarded).
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*/
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static void
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thread_fini(void *mem, int size)
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{
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struct thread *td;
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KASSERT((size == sizeof(struct thread)),
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("size mismatch: %d != %d\n", size, (int)sizeof(struct thread)));
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td = (struct thread *)mem;
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pmap_dispose_thread(td);
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}
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/*
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* Fill a ucontext_t with a thread's context information.
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*
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* This is an analogue to getcontext(3).
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*/
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void
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thread_getcontext(struct thread *td, ucontext_t *uc)
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{
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/*
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* XXX this is declared in a MD include file, i386/include/ucontext.h but
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* is used in MI code.
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*/
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#ifdef __i386__
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get_mcontext(td, &uc->uc_mcontext);
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#endif
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uc->uc_sigmask = td->td_proc->p_sigmask;
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}
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/*
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* Set a thread's context from a ucontext_t.
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*
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* This is an analogue to setcontext(3).
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*/
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int
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thread_setcontext(struct thread *td, ucontext_t *uc)
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{
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int ret;
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/*
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* XXX this is declared in a MD include file, i386/include/ucontext.h but
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* is used in MI code.
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*/
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#ifdef __i386__
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ret = set_mcontext(td, &uc->uc_mcontext);
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#else
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ret = ENOSYS;
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#endif
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if (ret == 0) {
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SIG_CANTMASK(uc->uc_sigmask);
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PROC_LOCK(td->td_proc);
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td->td_proc->p_sigmask = uc->uc_sigmask;
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PROC_UNLOCK(td->td_proc);
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}
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return (ret);
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}
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/*
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* Initialize global thread allocation resources.
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*/
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void
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threadinit(void)
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{
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thread_zone = uma_zcreate("THREAD", sizeof (struct thread),
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thread_ctor, thread_dtor, thread_init, thread_fini,
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UMA_ALIGN_CACHE, 0);
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ksegrp_zone = uma_zcreate("KSEGRP", sizeof (struct ksegrp),
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NULL, NULL, NULL, NULL,
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UMA_ALIGN_CACHE, 0);
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kse_zone = uma_zcreate("KSE", sizeof (struct kse),
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NULL, NULL, NULL, NULL,
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UMA_ALIGN_CACHE, 0);
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}
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/*
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* Stash an embarasingly extra thread into the zombie thread queue.
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*/
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void
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thread_stash(struct thread *td)
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{
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mtx_lock_spin(&zombie_thread_lock);
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TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq);
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mtx_unlock_spin(&zombie_thread_lock);
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}
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/*
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* Reap zombie threads.
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*/
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void
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thread_reap(void)
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{
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struct thread *td_reaped;
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/*
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* don't even bother to lock if none at this instant
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* We really don't care about the next instant..
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*/
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if (!TAILQ_EMPTY(&zombie_threads)) {
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mtx_lock_spin(&zombie_thread_lock);
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while (!TAILQ_EMPTY(&zombie_threads)) {
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td_reaped = TAILQ_FIRST(&zombie_threads);
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TAILQ_REMOVE(&zombie_threads, td_reaped, td_runq);
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mtx_unlock_spin(&zombie_thread_lock);
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thread_free(td_reaped);
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mtx_lock_spin(&zombie_thread_lock);
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}
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mtx_unlock_spin(&zombie_thread_lock);
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}
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}
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/*
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* Allocate a ksegrp.
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*/
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struct ksegrp *
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ksegrp_alloc(void)
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{
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return (uma_zalloc(ksegrp_zone, M_WAITOK));
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}
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/*
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* Allocate a kse.
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*/
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struct kse *
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kse_alloc(void)
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{
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return (uma_zalloc(kse_zone, M_WAITOK));
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}
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/*
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* Allocate a thread.
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*/
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struct thread *
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thread_alloc(void)
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{
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thread_reap(); /* check if any zombies to get */
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return (uma_zalloc(thread_zone, M_WAITOK));
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}
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/*
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* Deallocate a ksegrp.
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*/
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void
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ksegrp_free(struct ksegrp *td)
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{
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uma_zfree(ksegrp_zone, td);
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}
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/*
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* Deallocate a kse.
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*/
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void
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kse_free(struct kse *td)
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{
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uma_zfree(kse_zone, td);
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}
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/*
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* Deallocate a thread.
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*/
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void
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thread_free(struct thread *td)
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{
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uma_zfree(thread_zone, td);
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}
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/*
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* Store the thread context in the UTS's mailbox.
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*/
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int
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thread_export_context(struct thread *td)
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{
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struct kse *ke;
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uintptr_t td2_mbx;
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void *addr1;
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void *addr2;
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int error;
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ucontext_t uc;
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int unbound;
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unbound = (td->td_flags & TDF_UNBOUND);
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td->td_flags &= ~TDF_UNBOUND;
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#ifdef __ia64__
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td2_mbx = 0; /* pacify gcc (!) */
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#endif
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/* Export the user/machine context. */
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error = copyin((caddr_t)td->td_mailbox +
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offsetof(struct thread_mailbox, tm_context),
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&uc,
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sizeof(ucontext_t));
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if (error == 0) {
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thread_getcontext(td, &uc);
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error = copyout(&uc, (caddr_t)td->td_mailbox +
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offsetof(struct thread_mailbox, tm_context),
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sizeof(ucontext_t));
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}
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ke = td->td_kse;
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addr1 = (caddr_t)ke->ke_mailbox
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+ offsetof(struct kse_mailbox, km_completed);
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addr2 = (caddr_t)td->td_mailbox
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+ offsetof(struct thread_mailbox , tm_next);
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/* Then link it into it's KSE's list of completed threads. */
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if (!error) {
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error = td2_mbx = fuword(addr1);
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if (error == -1)
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error = EFAULT;
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else
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error = 0;
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}
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if (!error)
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error = suword(addr2, td2_mbx);
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if (!error)
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error = suword(addr1, (u_long)td->td_mailbox);
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if (error == -1)
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error = EFAULT;
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td->td_flags |= unbound;
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return (error);
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}
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/*
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* Discard the current thread and exit from its context.
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*
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* Because we can't free a thread while we're operating under its context,
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* push the current thread into our KSE's ke_tdspare slot, freeing the
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* thread that might be there currently. Because we know that only this
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* processor will run our KSE, we needn't worry about someone else grabbing
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* our context before we do a cpu_throw.
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*/
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void
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thread_exit(void)
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{
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struct thread *td;
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struct kse *ke;
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struct proc *p;
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struct ksegrp *kg;
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td = curthread;
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kg = td->td_ksegrp;
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p = td->td_proc;
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ke = td->td_kse;
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mtx_assert(&sched_lock, MA_OWNED);
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KASSERT(p != NULL, ("thread exiting without a process"));
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KASSERT(ke != NULL, ("thread exiting without a kse"));
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KASSERT(kg != NULL, ("thread exiting without a kse group"));
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PROC_LOCK_ASSERT(p, MA_OWNED);
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CTR1(KTR_PROC, "thread_exit: thread %p", td);
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KASSERT(!mtx_owned(&Giant), ("dying thread owns giant"));
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if (ke->ke_tdspare != NULL) {
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thread_stash(ke->ke_tdspare);
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ke->ke_tdspare = NULL;
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}
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cpu_thread_exit(td); /* XXXSMP */
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/*
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* The last thread is left attached to the process
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* So that the whole bundle gets recycled. Skip
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* all this stuff.
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*/
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if (p->p_numthreads > 1) {
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/* Reassign this thread's KSE. */
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ke->ke_thread = NULL;
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td->td_kse = NULL;
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ke->ke_state = KES_UNQUEUED;
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kse_reassign(ke);
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/* Unlink this thread from its proc. and the kseg */
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TAILQ_REMOVE(&p->p_threads, td, td_plist);
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p->p_numthreads--;
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TAILQ_REMOVE(&kg->kg_threads, td, td_kglist);
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kg->kg_numthreads--;
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/*
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* The test below is NOT true if we are the
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* sole exiting thread. P_STOPPED_SNGL is unset
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* in exit1() after it is the only survivor.
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*/
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if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
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if (p->p_numthreads == p->p_suspcount) {
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thread_unsuspend_one(p->p_singlethread);
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}
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}
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PROC_UNLOCK(p);
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td->td_state = TDS_INACTIVE;
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td->td_proc = NULL;
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td->td_ksegrp = NULL;
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td->td_last_kse = NULL;
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ke->ke_tdspare = td;
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} else {
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PROC_UNLOCK(p);
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}
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cpu_throw();
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/* NOTREACHED */
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}
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/*
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* Link a thread to a process.
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* set up anything that needs to be initialized for it to
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* be used by the process.
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*
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* Note that we do not link to the proc's ucred here.
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* The thread is linked as if running but no KSE assigned.
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*/
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void
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thread_link(struct thread *td, struct ksegrp *kg)
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{
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struct proc *p;
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p = kg->kg_proc;
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td->td_state = TDS_INACTIVE;
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td->td_proc = p;
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td->td_ksegrp = kg;
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td->td_last_kse = NULL;
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LIST_INIT(&td->td_contested);
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callout_init(&td->td_slpcallout, 1);
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TAILQ_INSERT_HEAD(&p->p_threads, td, td_plist);
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TAILQ_INSERT_HEAD(&kg->kg_threads, td, td_kglist);
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p->p_numthreads++;
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kg->kg_numthreads++;
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if (oiks_debug && p->p_numthreads > max_threads_per_proc) {
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printf("OIKS %d\n", p->p_numthreads);
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if (oiks_debug > 1)
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Debugger("OIKS");
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}
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td->td_kse = NULL;
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}
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/*
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* Create a thread and schedule it for upcall on the KSE given.
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*/
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struct thread *
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thread_schedule_upcall(struct thread *td, struct kse *ke)
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{
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struct thread *td2;
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mtx_assert(&sched_lock, MA_OWNED);
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if (ke->ke_tdspare != NULL) {
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td2 = ke->ke_tdspare;
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ke->ke_tdspare = NULL;
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} else {
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mtx_unlock_spin(&sched_lock);
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td2 = thread_alloc();
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mtx_lock_spin(&sched_lock);
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}
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CTR3(KTR_PROC, "thread_schedule_upcall: thread %p (pid %d, %s)",
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td, td->td_proc->p_pid, td->td_proc->p_comm);
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bzero(&td2->td_startzero,
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(unsigned)RANGEOF(struct thread, td_startzero, td_endzero));
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bcopy(&td->td_startcopy, &td2->td_startcopy,
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(unsigned) RANGEOF(struct thread, td_startcopy, td_endcopy));
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thread_link(td2, ke->ke_ksegrp);
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cpu_set_upcall(td2, td->td_pcb);
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bcopy(td->td_frame, td2->td_frame, sizeof(struct trapframe));
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/*
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* The user context for this thread is selected when we choose
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* a KSE and return to userland on it. All we need do here is
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* note that the thread exists in order to perform an upcall.
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*
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* Since selecting a KSE to perform the upcall involves locking
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* that KSE's context to our upcall, its best to wait until the
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* last possible moment before grabbing a KSE. We do this in
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* userret().
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*/
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td2->td_ucred = crhold(td->td_ucred);
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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 KSE's list of completed threads.
|
|
*/
|
|
error = thread_export_context(td);
|
|
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 perfom 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).
|
|
*
|
|
* XXXKSE Future enhancement: Shove threads in this
|
|
* state onto a list of completed threads hanging
|
|
* off the KSEG. Then, collect them before performing
|
|
* an upcall. This way, we don't commit to an upcall
|
|
* on a particular KSE, but report completed threads on
|
|
* the next upcall to any KSE in this KSEG.
|
|
*
|
|
*/
|
|
thread_exit(); /* Abandon current thread. */
|
|
/* NOTREACHED */
|
|
} else
|
|
/*
|
|
* 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;
|
|
|
|
#if 0
|
|
/*
|
|
* Ensure that we have a spare thread available.
|
|
*/
|
|
if (ke->ke_tdspare == NULL) {
|
|
mtx_lock(&Giant);
|
|
ke->ke_tdspare = thread_alloc();
|
|
mtx_unlock(&Giant);
|
|
}
|
|
#endif
|
|
/*
|
|
* Bound threads need no additional work.
|
|
*/
|
|
if ((td->td_flags & TDF_UNBOUND) == 0)
|
|
return (0);
|
|
error = 0;
|
|
/*
|
|
* Decide whether or not we should perform an upcall now.
|
|
*/
|
|
if (((td->td_flags & TDF_UPCALLING) == 0) && td->td_mailbox) {
|
|
error = thread_consider_upcalling(td);
|
|
if (error != 0)
|
|
/*
|
|
* Failing to do the KSE operation just defaults
|
|
* back to synchonous operation, so just return from
|
|
* the syscall.
|
|
*/
|
|
goto cont;
|
|
}
|
|
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.
|
|
*/
|
|
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.
|
|
*/
|
|
td->td_flags &= ~TDF_UNBOUND;
|
|
cpu_set_upcall_kse(td, td->td_kse);
|
|
if (error)
|
|
/*
|
|
* Failing to do the KSE operation just defaults
|
|
* back to synchonous operation, so just return from
|
|
* the syscall.
|
|
*/
|
|
goto cont;
|
|
|
|
/*
|
|
* Set state and mailbox.
|
|
*/
|
|
td->td_flags &= ~TDF_UPCALLING;
|
|
error = suword((caddr_t)td->td_kse->ke_mailbox +
|
|
offsetof(struct kse_mailbox, km_curthread),
|
|
0);
|
|
}
|
|
cont:
|
|
/*
|
|
* 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.
|
|
*/
|
|
td->td_flags &= ~TDF_UNBOUND; /* Bind to this user thread. */
|
|
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);
|
|
|
|
/* 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 = 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_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);
|
|
}
|
|
}
|
|
|
|
|