1054 lines
28 KiB
C
1054 lines
28 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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/mutex.h>
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#include <sys/proc.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <sys/sched.h>
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#include <sys/sleepqueue.h>
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#include <sys/turnstile.h>
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#include <sys/ktr.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#include <vm/uma.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 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 thread_debug = 0;
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SYSCTL_INT(_kern_threads, OID_AUTO, debug, CTLFLAG_RW,
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&thread_debug, 0, "thread debug");
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int max_threads_per_proc = 1500;
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SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
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&max_threads_per_proc, 0, "Limit on threads per proc");
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int max_groups_per_proc = 1500;
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SYSCTL_INT(_kern_threads, OID_AUTO, max_groups_per_proc, CTLFLAG_RW,
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&max_groups_per_proc, 0, "Limit on thread groups per proc");
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int max_threads_hits;
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SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
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&max_threads_hits, 0, "");
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int virtual_cpu;
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#define RANGEOF(type, start, end) (offsetof(type, end) - offsetof(type, start))
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TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
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TAILQ_HEAD(, ksegrp) zombie_ksegrps = TAILQ_HEAD_INITIALIZER(zombie_ksegrps);
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struct mtx kse_zombie_lock;
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MTX_SYSINIT(kse_zombie_lock, &kse_zombie_lock, "kse zombie lock", MTX_SPIN);
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static int
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sysctl_kse_virtual_cpu(SYSCTL_HANDLER_ARGS)
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{
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int error, new_val;
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int def_val;
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def_val = mp_ncpus;
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if (virtual_cpu == 0)
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new_val = def_val;
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else
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new_val = virtual_cpu;
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error = sysctl_handle_int(oidp, &new_val, 0, req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (new_val < 0)
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return (EINVAL);
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virtual_cpu = new_val;
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return (0);
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}
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/* DEBUG ONLY */
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SYSCTL_PROC(_kern_threads, OID_AUTO, virtual_cpu, CTLTYPE_INT|CTLFLAG_RW,
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0, sizeof(virtual_cpu), sysctl_kse_virtual_cpu, "I",
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"debug virtual cpus");
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/*
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* Thread ID allocator. The allocator keeps track of assigned IDs by
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* using a bitmap. The bitmap is created in parts. The parts are linked
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* together.
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*/
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typedef u_long tid_bitmap_word;
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#define TID_IDS_PER_PART 1024
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#define TID_IDS_PER_IDX (sizeof(tid_bitmap_word) << 3)
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#define TID_BITMAP_SIZE (TID_IDS_PER_PART / TID_IDS_PER_IDX)
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#define TID_MIN (PID_MAX + 1)
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struct tid_bitmap_part {
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STAILQ_ENTRY(tid_bitmap_part) bmp_next;
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tid_bitmap_word bmp_bitmap[TID_BITMAP_SIZE];
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lwpid_t bmp_base;
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int bmp_free;
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};
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static STAILQ_HEAD(, tid_bitmap_part) tid_bitmap =
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STAILQ_HEAD_INITIALIZER(tid_bitmap);
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static uma_zone_t tid_zone;
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struct mtx tid_lock;
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MTX_SYSINIT(tid_lock, &tid_lock, "TID lock", MTX_DEF);
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/*
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* Prepare a thread for use.
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*/
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static int
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thread_ctor(void *mem, int size, void *arg, int flags)
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{
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struct thread *td;
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td = (struct thread *)mem;
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td->td_state = TDS_INACTIVE;
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td->td_oncpu = NOCPU;
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/*
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* Note that td_critnest begins life as 1 because the thread is not
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* running and is thereby implicitly waiting to be on the receiving
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* end of a context switch. A context switch must occur inside a
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* critical section, and in fact, includes hand-off of the sched_lock.
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* After a context switch to a newly created thread, it will release
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* sched_lock for the first time, and its td_critnest will hit 0 for
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* the first time. This happens on the far end of a context switch,
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* and when it context switches away from itself, it will in fact go
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* back into a critical section, and hand off the sched lock to the
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* next thread.
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*/
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td->td_critnest = 1;
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return (0);
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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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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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sched_newthread(td);
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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 int
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thread_init(void *mem, int size, int flags)
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{
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struct thread *td;
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struct tid_bitmap_part *bmp, *new;
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int bit, idx;
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td = (struct thread *)mem;
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mtx_lock(&tid_lock);
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STAILQ_FOREACH(bmp, &tid_bitmap, bmp_next) {
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if (bmp->bmp_free)
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break;
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}
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/* Create a new bitmap if we run out of free bits. */
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if (bmp == NULL) {
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mtx_unlock(&tid_lock);
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new = uma_zalloc(tid_zone, M_WAITOK);
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mtx_lock(&tid_lock);
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bmp = STAILQ_LAST(&tid_bitmap, tid_bitmap_part, bmp_next);
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if (bmp == NULL || bmp->bmp_free < TID_IDS_PER_PART/2) {
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/* 1=free, 0=assigned. This way we can use ffsl(). */
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memset(new->bmp_bitmap, ~0U, sizeof(new->bmp_bitmap));
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new->bmp_base = (bmp == NULL) ? TID_MIN :
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bmp->bmp_base + TID_IDS_PER_PART;
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new->bmp_free = TID_IDS_PER_PART;
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STAILQ_INSERT_TAIL(&tid_bitmap, new, bmp_next);
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bmp = new;
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new = NULL;
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}
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} else
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new = NULL;
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/* We have a bitmap with available IDs. */
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idx = 0;
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while (idx < TID_BITMAP_SIZE && bmp->bmp_bitmap[idx] == 0UL)
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idx++;
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bit = ffsl(bmp->bmp_bitmap[idx]) - 1;
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td->td_tid = bmp->bmp_base + idx * TID_IDS_PER_IDX + bit;
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bmp->bmp_bitmap[idx] &= ~(1UL << bit);
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bmp->bmp_free--;
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mtx_unlock(&tid_lock);
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if (new != NULL)
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uma_zfree(tid_zone, new);
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vm_thread_new(td, 0);
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cpu_thread_setup(td);
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td->td_sleepqueue = sleepq_alloc();
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td->td_turnstile = turnstile_alloc();
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td->td_sched = (struct td_sched *)&td[1];
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sched_newthread(td);
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return (0);
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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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struct tid_bitmap_part *bmp;
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lwpid_t tid;
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int bit, idx;
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td = (struct thread *)mem;
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turnstile_free(td->td_turnstile);
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sleepq_free(td->td_sleepqueue);
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vm_thread_dispose(td);
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STAILQ_FOREACH(bmp, &tid_bitmap, bmp_next) {
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if (td->td_tid >= bmp->bmp_base &&
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td->td_tid < bmp->bmp_base + TID_IDS_PER_PART)
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break;
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}
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KASSERT(bmp != NULL, ("No TID bitmap?"));
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mtx_lock(&tid_lock);
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tid = td->td_tid - bmp->bmp_base;
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idx = tid / TID_IDS_PER_IDX;
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bit = 1UL << (tid % TID_IDS_PER_IDX);
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bmp->bmp_bitmap[idx] |= bit;
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bmp->bmp_free++;
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mtx_unlock(&tid_lock);
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}
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/*
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* Initialize type-stable parts of a ksegrp (when newly created).
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*/
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static int
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ksegrp_init(void *mem, int size, int flags)
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{
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struct ksegrp *kg;
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kg = (struct ksegrp *)mem;
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kg->kg_sched = (struct kg_sched *)&kg[1];
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/* sched_newksegrp(kg); */
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return (0);
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}
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void
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ksegrp_link(struct ksegrp *kg, struct proc *p)
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{
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TAILQ_INIT(&kg->kg_threads);
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TAILQ_INIT(&kg->kg_runq); /* links with td_runq */
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TAILQ_INIT(&kg->kg_slpq); /* links with td_runq */
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TAILQ_INIT(&kg->kg_upcalls); /* all upcall structure in ksegrp */
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kg->kg_proc = p;
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/*
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* the following counters are in the -zero- section
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* and may not need clearing
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*/
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kg->kg_numthreads = 0;
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kg->kg_runnable = 0;
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kg->kg_numupcalls = 0;
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/* link it in now that it's consistent */
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p->p_numksegrps++;
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TAILQ_INSERT_HEAD(&p->p_ksegrps, kg, kg_ksegrp);
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}
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/*
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* Called from:
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* thread-exit()
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*/
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void
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ksegrp_unlink(struct ksegrp *kg)
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{
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struct proc *p;
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mtx_assert(&sched_lock, MA_OWNED);
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KASSERT((kg->kg_numthreads == 0), ("ksegrp_unlink: residual threads"));
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KASSERT((kg->kg_numupcalls == 0), ("ksegrp_unlink: residual upcalls"));
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p = kg->kg_proc;
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TAILQ_REMOVE(&p->p_ksegrps, kg, kg_ksegrp);
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p->p_numksegrps--;
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/*
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* Aggregate stats from the KSE
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*/
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}
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/*
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* For a newly created process,
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* link up all the structures and its initial threads etc.
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* called from:
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* {arch}/{arch}/machdep.c ia64_init(), init386() etc.
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* proc_dtor() (should go away)
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* proc_init()
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*/
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void
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proc_linkup(struct proc *p, struct ksegrp *kg, struct thread *td)
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{
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TAILQ_INIT(&p->p_ksegrps); /* all ksegrps in proc */
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TAILQ_INIT(&p->p_threads); /* all threads in proc */
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TAILQ_INIT(&p->p_suspended); /* Threads suspended */
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p->p_numksegrps = 0;
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p->p_numthreads = 0;
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ksegrp_link(kg, p);
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thread_link(td, kg);
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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", sched_sizeof_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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tid_zone = uma_zcreate("TID", sizeof(struct tid_bitmap_part),
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NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0);
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ksegrp_zone = uma_zcreate("KSEGRP", sched_sizeof_ksegrp(),
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NULL, NULL, ksegrp_init, NULL,
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UMA_ALIGN_CACHE, 0);
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kseinit(); /* set up kse specific stuff e.g. upcall zone*/
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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(&kse_zombie_lock);
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TAILQ_INSERT_HEAD(&zombie_threads, td, td_runq);
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mtx_unlock_spin(&kse_zombie_lock);
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}
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/*
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* Stash an embarasingly extra ksegrp into the zombie ksegrp queue.
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*/
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void
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ksegrp_stash(struct ksegrp *kg)
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{
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mtx_lock_spin(&kse_zombie_lock);
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TAILQ_INSERT_HEAD(&zombie_ksegrps, kg, kg_ksegrp);
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mtx_unlock_spin(&kse_zombie_lock);
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}
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/*
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* Reap zombie kse resource.
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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_first, *td_next;
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struct ksegrp *kg_first, * kg_next;
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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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|| (!TAILQ_EMPTY(&zombie_ksegrps))) {
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mtx_lock_spin(&kse_zombie_lock);
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td_first = TAILQ_FIRST(&zombie_threads);
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kg_first = TAILQ_FIRST(&zombie_ksegrps);
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if (td_first)
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TAILQ_INIT(&zombie_threads);
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if (kg_first)
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TAILQ_INIT(&zombie_ksegrps);
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mtx_unlock_spin(&kse_zombie_lock);
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while (td_first) {
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td_next = TAILQ_NEXT(td_first, td_runq);
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if (td_first->td_ucred)
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crfree(td_first->td_ucred);
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thread_free(td_first);
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td_first = td_next;
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}
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while (kg_first) {
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kg_next = TAILQ_NEXT(kg_first, kg_ksegrp);
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ksegrp_free(kg_first);
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kg_first = kg_next;
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}
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/*
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* there will always be a thread on the list if one of these
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* is there.
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*/
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kse_GC();
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}
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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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/*
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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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/*
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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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/*
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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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cpu_thread_clean(td);
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uma_zfree(thread_zone, td);
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}
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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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* Always called with scheduler locked.
|
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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 CPU's deadthread holder. This means
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* we needn't worry about someone else grabbing our context before we
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* do a cpu_throw(). This may not be needed now as we are under schedlock.
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* Maybe we can just do a thread_stash() as thr_exit1 does.
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*/
|
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/* XXX
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|
* libthr expects its thread exit to return for the last
|
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* 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.
|
|
*
|
|
* called from:
|
|
* exit1()
|
|
* kse_exit()
|
|
* thr_exit()
|
|
* thread_user_enter()
|
|
* thread_userret()
|
|
* thread_suspend_check()
|
|
*/
|
|
void
|
|
thread_exit(void)
|
|
{
|
|
struct thread *td;
|
|
struct proc *p;
|
|
struct ksegrp *kg;
|
|
|
|
td = curthread;
|
|
kg = td->td_ksegrp;
|
|
p = td->td_proc;
|
|
|
|
mtx_assert(&sched_lock, MA_OWNED);
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
KASSERT(p != NULL, ("thread exiting without a process"));
|
|
KASSERT(kg != NULL, ("thread exiting without a kse group"));
|
|
CTR3(KTR_PROC, "thread_exit: thread %p (pid %ld, %s)", td,
|
|
(long)p->p_pid, p->p_comm);
|
|
|
|
if (td->td_standin != NULL) {
|
|
/*
|
|
* Note that we don't need to free the cred here as it
|
|
* is done in thread_reap().
|
|
*/
|
|
thread_stash(td->td_standin);
|
|
td->td_standin = NULL;
|
|
}
|
|
|
|
/*
|
|
* drop FPU & debug register state storage, or any other
|
|
* architecture specific resources that
|
|
* would not be on a new untouched process.
|
|
*/
|
|
cpu_thread_exit(td); /* XXXSMP */
|
|
|
|
/*
|
|
* The thread is exiting. scheduler can release its stuff
|
|
* and collect stats etc.
|
|
*/
|
|
sched_thread_exit(td);
|
|
|
|
/*
|
|
* The last thread is left attached to the process
|
|
* So that the whole bundle gets recycled. Skip
|
|
* all this stuff if we never had threads.
|
|
* EXIT clears all sign of other threads when
|
|
* it goes to single threading, so the last thread always
|
|
* takes the short path.
|
|
*/
|
|
if (p->p_flag & P_HADTHREADS) {
|
|
if (p->p_numthreads > 1) {
|
|
thread_unlink(td);
|
|
|
|
/* XXX first arg not used in 4BSD or ULE */
|
|
sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
|
|
|
|
/*
|
|
* as we are exiting there is room for another
|
|
* to be created.
|
|
*/
|
|
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.
|
|
* XXXKSE This is a KSE thing and should be exported
|
|
* there somehow.
|
|
*/
|
|
upcall_remove(td);
|
|
|
|
/*
|
|
* If the thread we unlinked above was the last one,
|
|
* then this ksegrp should go away too.
|
|
*/
|
|
if (kg->kg_numthreads == 0) {
|
|
/*
|
|
* let the scheduler know about this in case
|
|
* it needs to recover stats or resources.
|
|
* Theoretically we could let
|
|
* sched_exit_ksegrp() do the equivalent of
|
|
* setting the concurrency to 0
|
|
* but don't do it yet to avoid changing
|
|
* the existing scheduler code until we
|
|
* are ready.
|
|
* We supply a random other ksegrp
|
|
* as the recipient of any built up
|
|
* cpu usage etc. (If the scheduler wants it).
|
|
* XXXKSE
|
|
* This is probably not fair so think of
|
|
* a better answer.
|
|
*/
|
|
sched_exit_ksegrp(FIRST_KSEGRP_IN_PROC(p), td);
|
|
sched_set_concurrency(kg, 0); /* XXX TEMP */
|
|
ksegrp_unlink(kg);
|
|
ksegrp_stash(kg);
|
|
}
|
|
PROC_UNLOCK(p);
|
|
td->td_ksegrp = NULL;
|
|
PCPU_SET(deadthread, td);
|
|
} else {
|
|
/*
|
|
* The last thread is exiting.. but not through exit()
|
|
* what should we do?
|
|
* Theoretically this can't happen
|
|
* exit1() - clears threading flags before coming here
|
|
* kse_exit() - treats last thread specially
|
|
* thr_exit() - treats last thread specially
|
|
* thread_user_enter() - only if more exist
|
|
* thread_userret() - only if more exist
|
|
* thread_suspend_check() - only if more exist
|
|
*/
|
|
panic ("thread_exit: Last thread exiting on its own");
|
|
}
|
|
} else {
|
|
/*
|
|
* non threaded process comes here.
|
|
* This includes an EX threaded process that is coming
|
|
* here via exit1(). (exit1 dethreads the proc first).
|
|
*/
|
|
PROC_UNLOCK(p);
|
|
}
|
|
td->td_state = TDS_INACTIVE;
|
|
CTR1(KTR_PROC, "thread_exit: cpu_throw() thread %p", td);
|
|
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) {
|
|
crfree(td->td_ucred);
|
|
td->td_ucred = NULL;
|
|
thread_free(td->td_standin);
|
|
td->td_standin = NULL;
|
|
}
|
|
cpu_thread_clean(td);
|
|
crfree(td->td_ucred);
|
|
}
|
|
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.
|
|
* Called from:
|
|
* proc_linkup()
|
|
* thread_schedule_upcall()
|
|
* thr_create()
|
|
*/
|
|
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_flags = 0;
|
|
td->td_kflags = 0;
|
|
|
|
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++;
|
|
}
|
|
|
|
/*
|
|
* Called from:
|
|
* thread_exit()
|
|
*/
|
|
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 */
|
|
/* Must NOT clear links to proc and ksegrp! */
|
|
}
|
|
|
|
/*
|
|
* 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_HADTHREADS) == 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;
|
|
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->td_flags & TDF_DBSUSPEND)
|
|
td->td_flags &= ~TDF_DBSUSPEND;
|
|
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, NULL);
|
|
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) {
|
|
/*
|
|
* We have gotten rid of all the other threads and we
|
|
* are about to either exit or exec. In either case,
|
|
* we try our utmost to revert to being a non-threaded
|
|
* process.
|
|
*/
|
|
upcall_remove(td);
|
|
p->p_flag &= ~(P_SA|P_HADTHREADS);
|
|
td->td_mailbox = NULL;
|
|
td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND);
|
|
p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
|
|
p->p_singlethread = NULL;
|
|
if (td->td_standin != NULL) {
|
|
thread_stash(td->td_standin);
|
|
td->td_standin = NULL;
|
|
}
|
|
sched_set_concurrency(td->td_ksegrp, 1);
|
|
mtx_unlock_spin(&sched_lock);
|
|
} else {
|
|
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) ||
|
|
((p->p_flag & P_TRACED) && (td->td_flags & TDF_DBSUSPEND))) {
|
|
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 ((p->p_flag & P_SINGLE_EXIT) && 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)) {
|
|
thread_exit();
|
|
}
|
|
|
|
/*
|
|
* 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, NULL);
|
|
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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* End the single threading mode..
|
|
* Part of this is duplicated in thread-single in the SINGLE_EXIT case.
|
|
*/
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* Called before going into an interruptible sleep to see if we have been
|
|
* interrupted or requested to exit.
|
|
*/
|
|
int
|
|
thread_sleep_check(struct thread *td)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = td->td_proc;
|
|
mtx_assert(&sched_lock, MA_OWNED);
|
|
if (p->p_flag & P_HADTHREADS) {
|
|
if ((p->p_flag & P_SINGLE_EXIT) && p->p_singlethread != td)
|
|
return (EINTR);
|
|
if (td->td_flags & TDF_INTERRUPT)
|
|
return (td->td_intrval);
|
|
}
|
|
return (0);
|
|
}
|