common/cpr/cpr_uthread.c

	cpr_uthread.c revision 2df1fe9ca32bb227b9158c67f5c00b54c20b10fd
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/thread.h>
#include <sys/conf.h>
#include <sys/cpuvar.h>
#include <sys/cpr.h>
#include <sys/user.h>
#include <sys/cmn_err.h>
#include <sys/callb.h>

extern void utstop_init(void);
extern void add_one_utstop(void);
extern void utstop_timedwait(long ticks);

static void cpr_stop_user(int);
static int cpr_check_user_threads(void);

/*
 * CPR user thread related support routines
 */
void
cpr_signal_user(int sig)
{
/*
 * The signal SIGTHAW and SIGFREEZE cannot be sent to every thread yet
 * since openwin is catching every signal and default action is to exit.
 * We also need to implement the true SIGFREEZE and SIGTHAW to stop threads.
 */
    struct proc *p;

    mutex_enter(&pidlock);

    for (p = practive; p; p = p->p_next) {
        /* only user threads */
        if (p->p_exec == NULL || p->p_stat == SZOMB ||
            p == proc_init || p == ttoproc(curthread))
            continue;

        mutex_enter(&p->p_lock);
        sigtoproc(p, NULL, sig);
        mutex_exit(&p->p_lock);
    }
    mutex_exit(&pidlock);

    DELAY(MICROSEC);
}

/* max wait time for user thread stop */
#define CPR_UTSTOP_WAIT     hz
#define CPR_UTSTOP_RETRY    4
static int count;

int
cpr_stop_user_threads()
{
    utstop_init();

    count = 0;
    do {
        if (++count > CPR_UTSTOP_RETRY)
            return (ESRCH);
        cpr_stop_user(count * count * CPR_UTSTOP_WAIT);
    } while (cpr_check_user_threads() &&
        (count < CPR_UTSTOP_RETRY || CPR->c_fcn != AD_CPR_FORCE));

    return (0);
}

/*
 * This routine tries to stop all user threads before we get rid of all
 * its pages.It goes through allthreads list and set the TP_CHKPT flag
 * for all user threads and make them runnable. If all of the threads
 * can be stopped within the max wait time, CPR will proceed. Otherwise
 * CPR is aborted after a few of similiar retries.
 */
static void
cpr_stop_user(int wait)
{
    kthread_id_t tp;
    proc_t *p;

    /* The whole loop below needs to be atomic */
    mutex_enter(&pidlock);

    /* faster this way */
    tp = curthread->t_next;
    do {
        /* kernel threads will be handled later */
        p = ttoproc(tp);
        if (p->p_as == &kas || p->p_stat == SZOMB)
            continue;

        /*
         * If the thread is stopped (by CPR) already, do nothing;
         * if running, mark TP_CHKPT;
         * if sleeping normally, mark TP_CHKPT and setrun;
         * if sleeping non-interruptable, mark TP_CHKPT only for now;
         * if sleeping with t_wchan0 != 0 etc, virtually stopped,
         * do nothing.
         */

        /* p_lock is needed for modifying t_proc_flag */
        mutex_enter(&p->p_lock);
        thread_lock(tp); /* needed to check CPR_ISTOPPED */

        if (tp->t_state == TS_STOPPED) {
            /*
             * if already stopped by other reasons, add this new
             * reason to it.
             */
            if (tp->t_schedflag & TS_RESUME)
                tp->t_schedflag &= ~TS_RESUME;
        } else {

            tp->t_proc_flag |= TP_CHKPT;

            thread_unlock(tp);
            mutex_exit(&p->p_lock);
            add_one_utstop();
            mutex_enter(&p->p_lock);
            thread_lock(tp);

            aston(tp);

            if (ISWAKEABLE(tp) || ISWAITING(tp)) {
                setrun_locked(tp);
            }
        }
        /*
         * force the thread into the kernel if it is not already there.
         */
        if (tp->t_state == TS_ONPROC && tp->t_cpu != CPU)
            poke_cpu(tp->t_cpu->cpu_id);
        thread_unlock(tp);
        mutex_exit(&p->p_lock);

    } while ((tp = tp->t_next) != curthread);
    mutex_exit(&pidlock);

    utstop_timedwait(wait);
}

/*
 * Checks and makes sure all user threads are stopped
 */
static int
cpr_check_user_threads()
{
    kthread_id_t tp;
    int rc = 0;

    mutex_enter(&pidlock);
    tp = curthread->t_next;
    do {
        if (ttoproc(tp)->p_as == &kas || ttoproc(tp)->p_stat == SZOMB)
            continue;

        thread_lock(tp);
        /*
         * make sure that we are off all the queues and in a stopped
         * state.
         */
        if (!CPR_ISTOPPED(tp)) {
            thread_unlock(tp);
            mutex_exit(&pidlock);

            if (count == CPR_UTSTOP_RETRY) {
            CPR_DEBUG(CPR_DEBUG1, "Suspend failed: "
                "cannot stop uthread\n");
            cpr_err(CE_WARN, "Suspend cannot stop "
                "process %s (%p:%x).",
                ttoproc(tp)->p_user.u_psargs, (void *)tp,
                tp->t_state);
            cpr_err(CE_WARN, "Process may be waiting for"
                " network request, please try again.");
            }

            CPR_DEBUG(CPR_DEBUG2, "cant stop t=%p state=%x pfg=%x "
                "sched=%x\n", tp, tp->t_state, tp->t_proc_flag,
                tp->t_schedflag);
            CPR_DEBUG(CPR_DEBUG2, "proc %p state=%x pid=%d\n",
                ttoproc(tp), ttoproc(tp)->p_stat,
                ttoproc(tp)->p_pidp->pid_id);
            return (1);
        }
        thread_unlock(tp);

    } while ((tp = tp->t_next) != curthread && rc == 0);

    mutex_exit(&pidlock);
    return (0);
}


/*
 * start all threads that were stopped for checkpoint.
 */
void
cpr_start_user_threads()
{
    kthread_id_t tp;
    proc_t *p;

    mutex_enter(&pidlock);
    tp = curthread->t_next;
    do {
        p = ttoproc(tp);
        /*
         * kernel threads are callback'ed rather than setrun.
         */
        if (ttoproc(tp)->p_as == &kas) continue;
        /*
         * t_proc_flag should have been cleared. Just to make sure here
         */
        mutex_enter(&p->p_lock);
        tp->t_proc_flag &= ~TP_CHKPT;
        mutex_exit(&p->p_lock);

        thread_lock(tp);
        if (CPR_ISTOPPED(tp)) {

            /*
             * put it back on the runq
             */
            tp->t_schedflag |= TS_RESUME;
            setrun_locked(tp);
        }
        thread_unlock(tp);
        /*
         * DEBUG - Keep track of current and next thread pointer.
         */
    } while ((tp = tp->t_next) != curthread);

    mutex_exit(&pidlock);
}


/*
 * re/start kernel threads
 */
void
cpr_start_kernel_threads(void)
{
    CPR_DEBUG(CPR_DEBUG1, "starting kernel daemons...");
    (void) callb_execute_class(CB_CL_CPR_DAEMON, CB_CODE_CPR_RESUME);
    CPR_DEBUG(CPR_DEBUG1, "done\n");

    /* see table lock below */
    callb_unlock_table();
}


/*
 * Stop kernel threads by using the callback mechanism.  If any thread
 * cannot be stopped, return failure.
 */
int
cpr_stop_kernel_threads(void)
{
    caddr_t name;

    callb_lock_table(); /* Note: we unlock the table in resume. */

    CPR_DEBUG(CPR_DEBUG1, "stopping kernel daemons...");
    if ((name = callb_execute_class(CB_CL_CPR_DAEMON,
        CB_CODE_CPR_CHKPT)) != (caddr_t)NULL) {
        cpr_err(CE_WARN,
            "Could not stop \"%s\" kernel thread.  "
            "Please try again later.", name);
        return (EBUSY);
    }

    CPR_DEBUG(CPR_DEBUG1, ("done\n"));
    return (0);
}

/*
 * Check to see that kernel threads are stopped.
 * This should be called while CPU's are paused, and the caller is
 * effectively running single user, or else we are virtually guaranteed
 * to fail.  The routine should not ASSERT on the paused state or spl
 * level, as there may be a use for this to verify that things are running
 * again.
 */
int
cpr_threads_are_stopped(void)
{
    caddr_t name;
    kthread_id_t tp;
    proc_t *p;

    /*
     * We think we stopped all the kernel threads.  Just in case
     * someone is not playing by the rules, take a spin through
     * the threadlist and see if we can account for everybody.
     */
    mutex_enter(&pidlock);
    tp = curthread->t_next;
    do {
        p = ttoproc(tp);
        if (p->p_as != &kas)
            continue;

        if (tp->t_flag & T_INTR_THREAD)
            continue;

        if (! callb_is_stopped(tp, &name)) {
            mutex_exit(&pidlock);
            cpr_err(CE_WARN,
                "\"%s\" kernel thread not stopped.", name);
            return (EBUSY);
        }
    } while ((tp = tp->t_next) != curthread);

    mutex_exit(&pidlock);
    return (0);
}