03435f0383
It is often useful for developers and administrators to determine a running thread's stack for debugging purposes. With this feature, using ^T will print that information For now, the feature is disabled by default. Enable with sysctl kern.tty_info_kstacks=1. Discussed with: markj Reviewed by: oshogbo Relnotes: yes Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D17621
369 lines
9.3 KiB
C
369 lines
9.3 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1990, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Copyright (c) 2002 Networks Associates Technologies, Inc.
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* All rights reserved.
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*
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* Portions of this software were developed for the FreeBSD Project by
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* ThinkSec AS and NAI Labs, the Security Research Division of Network
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* Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
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* ("CBOSS"), as part of the DARPA CHATS research program.
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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, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, 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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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER 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
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* SUCH 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/cons.h>
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#include <sys/kdb.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/resourcevar.h>
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#include <sys/sbuf.h>
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#include <sys/sched.h>
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#include <sys/stack.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <sys/tty.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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/*
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* Returns 1 if p2 is "better" than p1
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*
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* The algorithm for picking the "interesting" process is thus:
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*
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* 1) Only foreground processes are eligible - implied.
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* 2) Runnable processes are favored over anything else. The runner
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* with the highest cpu utilization is picked (p_estcpu). Ties are
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* broken by picking the highest pid.
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* 3) The sleeper with the shortest sleep time is next. With ties,
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* we pick out just "short-term" sleepers (P_SINTR == 0).
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* 4) Further ties are broken by picking the highest pid.
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*/
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#define TESTAB(a, b) ((a)<<1 | (b))
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#define ONLYA 2
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#define ONLYB 1
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#define BOTH 3
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static int
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proc_sum(struct proc *p, fixpt_t *estcpup)
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{
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struct thread *td;
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int estcpu;
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int val;
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val = 0;
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estcpu = 0;
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FOREACH_THREAD_IN_PROC(p, td) {
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thread_lock(td);
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if (TD_ON_RUNQ(td) ||
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TD_IS_RUNNING(td))
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val = 1;
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estcpu += sched_pctcpu(td);
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thread_unlock(td);
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}
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*estcpup = estcpu;
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return (val);
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}
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static int
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thread_compare(struct thread *td, struct thread *td2)
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{
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int runa, runb;
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int slpa, slpb;
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fixpt_t esta, estb;
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if (td == NULL)
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return (1);
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/*
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* Fetch running stats, pctcpu usage, and interruptable flag.
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*/
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thread_lock(td);
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runa = TD_IS_RUNNING(td) | TD_ON_RUNQ(td);
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slpa = td->td_flags & TDF_SINTR;
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esta = sched_pctcpu(td);
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thread_unlock(td);
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thread_lock(td2);
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runb = TD_IS_RUNNING(td2) | TD_ON_RUNQ(td2);
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estb = sched_pctcpu(td2);
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slpb = td2->td_flags & TDF_SINTR;
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thread_unlock(td2);
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/*
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* see if at least one of them is runnable
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*/
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switch (TESTAB(runa, runb)) {
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case ONLYA:
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return (0);
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case ONLYB:
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return (1);
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case BOTH:
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break;
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}
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/*
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* favor one with highest recent cpu utilization
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*/
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if (estb > esta)
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return (1);
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if (esta > estb)
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return (0);
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/*
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* favor one sleeping in a non-interruptible sleep
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*/
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switch (TESTAB(slpa, slpb)) {
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case ONLYA:
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return (0);
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case ONLYB:
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return (1);
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case BOTH:
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break;
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}
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return (td < td2);
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}
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static int
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proc_compare(struct proc *p1, struct proc *p2)
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{
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int runa, runb;
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fixpt_t esta, estb;
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if (p1 == NULL)
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return (1);
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/*
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* Fetch various stats about these processes. After we drop the
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* lock the information could be stale but the race is unimportant.
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*/
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PROC_LOCK(p1);
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runa = proc_sum(p1, &esta);
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PROC_UNLOCK(p1);
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PROC_LOCK(p2);
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runb = proc_sum(p2, &estb);
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PROC_UNLOCK(p2);
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/*
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* see if at least one of them is runnable
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*/
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switch (TESTAB(runa, runb)) {
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case ONLYA:
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return (0);
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case ONLYB:
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return (1);
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case BOTH:
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break;
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}
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/*
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* favor one with highest recent cpu utilization
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*/
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if (estb > esta)
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return (1);
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if (esta > estb)
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return (0);
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/*
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* weed out zombies
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*/
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switch (TESTAB(p1->p_state == PRS_ZOMBIE, p2->p_state == PRS_ZOMBIE)) {
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case ONLYA:
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return (1);
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case ONLYB:
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return (0);
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case BOTH:
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break;
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}
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return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
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}
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static int
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sbuf_tty_drain(void *a, const char *d, int len)
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{
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struct tty *tp;
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int rc;
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tp = a;
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if (kdb_active) {
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cnputsn(d, len);
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return (len);
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}
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if (tp != NULL && panicstr == NULL) {
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rc = tty_putstrn(tp, d, len);
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if (rc != 0)
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return (-ENXIO);
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return (len);
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}
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return (-ENXIO);
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}
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static bool tty_info_kstacks = false;
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SYSCTL_BOOL(_kern, OID_AUTO, tty_info_kstacks, CTLFLAG_RWTUN,
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&tty_info_kstacks, 0,
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"Enable printing kernel stack(9) traces on ^T (tty info)");
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/*
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* Report on state of foreground process group.
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*/
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void
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tty_info(struct tty *tp)
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{
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struct timeval rtime, utime, stime;
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struct stack stack;
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struct proc *p, *ppick;
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struct thread *td, *tdpick;
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const char *stateprefix, *state;
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struct sbuf sb;
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long rss;
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int load, pctcpu, sterr;
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pid_t pid;
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char comm[MAXCOMLEN + 1];
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struct rusage ru;
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tty_lock_assert(tp, MA_OWNED);
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if (tty_checkoutq(tp) == 0)
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return;
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(void)sbuf_new(&sb, tp->t_prbuf, sizeof(tp->t_prbuf), SBUF_FIXEDLEN);
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sbuf_set_drain(&sb, sbuf_tty_drain, tp);
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/* Print load average. */
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load = (averunnable.ldavg[0] * 100 + FSCALE / 2) >> FSHIFT;
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sbuf_printf(&sb, "%sload: %d.%02d ", tp->t_column == 0 ? "" : "\n",
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load / 100, load % 100);
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if (tp->t_session == NULL) {
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sbuf_printf(&sb, "not a controlling terminal\n");
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goto out;
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}
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if (tp->t_pgrp == NULL) {
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sbuf_printf(&sb, "no foreground process group\n");
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goto out;
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}
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PGRP_LOCK(tp->t_pgrp);
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if (LIST_EMPTY(&tp->t_pgrp->pg_members)) {
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PGRP_UNLOCK(tp->t_pgrp);
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sbuf_printf(&sb, "empty foreground process group\n");
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goto out;
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}
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/*
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* Pick the most interesting process and copy some of its
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* state for printing later. This operation could rely on stale
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* data as we can't hold the proc slock or thread locks over the
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* whole list. However, we're guaranteed not to reference an exited
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* thread or proc since we hold the tty locked.
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*/
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p = NULL;
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LIST_FOREACH(ppick, &tp->t_pgrp->pg_members, p_pglist)
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if (proc_compare(p, ppick))
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p = ppick;
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PROC_LOCK(p);
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PGRP_UNLOCK(tp->t_pgrp);
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td = NULL;
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FOREACH_THREAD_IN_PROC(p, tdpick)
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if (thread_compare(td, tdpick))
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td = tdpick;
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stateprefix = "";
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thread_lock(td);
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if (TD_IS_RUNNING(td))
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state = "running";
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else if (TD_ON_RUNQ(td) || TD_CAN_RUN(td))
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state = "runnable";
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else if (TD_IS_SLEEPING(td)) {
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/* XXX: If we're sleeping, are we ever not in a queue? */
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if (TD_ON_SLEEPQ(td))
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state = td->td_wmesg;
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else
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state = "sleeping without queue";
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} else if (TD_ON_LOCK(td)) {
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state = td->td_lockname;
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stateprefix = "*";
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} else if (TD_IS_SUSPENDED(td))
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state = "suspended";
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else if (TD_AWAITING_INTR(td))
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state = "intrwait";
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else if (p->p_state == PRS_ZOMBIE)
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state = "zombie";
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else
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state = "unknown";
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pctcpu = (sched_pctcpu(td) * 10000 + FSCALE / 2) >> FSHIFT;
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if (tty_info_kstacks) {
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stack_zero(&stack);
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if (TD_IS_SWAPPED(td) || TD_IS_RUNNING(td))
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sterr = stack_save_td_running(&stack, td);
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else {
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stack_save_td(&stack, td);
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sterr = 0;
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}
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}
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thread_unlock(td);
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if (p->p_state == PRS_NEW || p->p_state == PRS_ZOMBIE)
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rss = 0;
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else
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rss = pgtok(vmspace_resident_count(p->p_vmspace));
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microuptime(&rtime);
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timevalsub(&rtime, &p->p_stats->p_start);
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rufetchcalc(p, &ru, &utime, &stime);
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pid = p->p_pid;
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strlcpy(comm, p->p_comm, sizeof comm);
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PROC_UNLOCK(p);
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/* Print command, pid, state, rtime, utime, stime, %cpu, and rss. */
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sbuf_printf(&sb,
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" cmd: %s %d [%s%s] %ld.%02ldr %ld.%02ldu %ld.%02lds %d%% %ldk\n",
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comm, pid, stateprefix, state,
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(long)rtime.tv_sec, rtime.tv_usec / 10000,
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(long)utime.tv_sec, utime.tv_usec / 10000,
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(long)stime.tv_sec, stime.tv_usec / 10000,
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pctcpu / 100, rss);
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if (tty_info_kstacks && sterr == 0)
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stack_sbuf_print_flags(&sb, &stack, M_NOWAIT);
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out:
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sbuf_finish(&sb);
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sbuf_delete(&sb);
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}
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