/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#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", (void *)tp, tp->t_state,
                            tp->t_proc_flag, tp->t_schedflag);
                        CPR_DEBUG(CPR_DEBUG2, "proc %p state=%x pid=%d\n",
                            (void *)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);
}