6451855f6d
mutex operations in kthread_create(). - Lock a kthread's proc before changing its parent via proc_reparent(). - Test P_KTHREAD not P_SYSTEM in kthread_suspend() and kthread_resume(). P_SYSTEM just means that the process shouldn't be swapped and is used for vinum's daemon for example. - Lock all the signal state used for suspending and resuming kthreads with the proc lock.
177 lines
4.6 KiB
C
177 lines
4.6 KiB
C
/*
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* Copyright (c) 1999 Peter Wemm <peter@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, 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/proc.h>
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#include <sys/kthread.h>
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#include <sys/lock.h>
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#include <sys/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/unistd.h>
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#include <sys/wait.h>
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#include <machine/stdarg.h>
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/*
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* Start a kernel process. This is called after a fork() call in
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* mi_startup() in the file kern/init_main.c.
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*
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* This function is used to start "internal" daemons and intended
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* to be called from SYSINIT().
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*/
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void
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kproc_start(udata)
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const void *udata;
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{
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const struct kproc_desc *kp = udata;
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int error;
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error = kthread_create((void (*)(void *))kp->func, NULL,
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kp->global_procpp, 0, kp->arg0);
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if (error)
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panic("kproc_start: %s: error %d", kp->arg0, error);
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}
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/*
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* Create a kernel process/thread/whatever. It shares its address space
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* with proc0 - ie: kernel only.
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*
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* func is the function to start.
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* arg is the parameter to pass to function on first startup.
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* newpp is the return value pointing to the thread's struct proc.
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* flags are flags to fork1 (in unistd.h)
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* fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
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*/
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int
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kthread_create(void (*func)(void *), void *arg,
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struct proc **newpp, int flags, const char *fmt, ...)
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{
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int error;
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va_list ap;
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struct proc *p2;
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if (!proc0.p_stats /* || proc0.p_stats->p_start.tv_sec == 0 */)
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panic("kthread_create called too soon");
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error = fork1(&proc0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags, &p2);
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if (error)
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return error;
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/* save a global descriptor, if desired */
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if (newpp != NULL)
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*newpp = p2;
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/* this is a non-swapped system process */
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PROC_LOCK(p2);
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p2->p_flag |= P_SYSTEM | P_KTHREAD;
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p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
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_PHOLD(p2);
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PROC_UNLOCK(p2);
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/* set up arg0 for 'ps', et al */
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va_start(ap, fmt);
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vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
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va_end(ap);
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/* call the processes' main()... */
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cpu_set_fork_handler(p2, func, arg);
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/* Delay putting it on the run queue until now. */
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mtx_lock_spin(&sched_lock);
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p2->p_sflag |= PS_INMEM;
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if (!(flags & RFSTOPPED)) {
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p2->p_stat = SRUN;
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setrunqueue(p2);
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}
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mtx_unlock_spin(&sched_lock);
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return 0;
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}
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void
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kthread_exit(int ecode)
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{
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PROCTREE_LOCK(PT_EXCLUSIVE);
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PROC_LOCK(curproc);
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proc_reparent(curproc, initproc);
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PROC_UNLOCK(curproc);
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PROCTREE_LOCK(PT_RELEASE);
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exit1(curproc, W_EXITCODE(ecode, 0));
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}
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/*
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* Advise a kernel process to suspend (or resume) in its main loop.
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* Participation is voluntary.
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*/
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int
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kthread_suspend(struct proc *p, int timo)
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{
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/*
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* Make sure this is indeed a system process and we can safely
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* use the p_siglist field.
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*/
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PROC_LOCK(p);
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if ((p->p_flag & P_KTHREAD) == 0) {
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PROC_UNLOCK(p);
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return (EINVAL);
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}
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SIGADDSET(p->p_siglist, SIGSTOP);
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return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkt", timo);
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}
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int
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kthread_resume(struct proc *p)
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{
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/*
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* Make sure this is indeed a system process and we can safely
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* use the p_siglist field.
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*/
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PROC_LOCK(p);
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if ((p->p_flag & P_KTHREAD) == 0) {
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PROC_UNLOCK(p);
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return (EINVAL);
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}
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SIGDELSET(p->p_siglist, SIGSTOP);
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PROC_UNLOCK(p);
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wakeup(&p->p_siglist);
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return (0);
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}
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void
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kthread_suspend_check(struct proc *p)
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{
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PROC_LOCK(p);
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while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
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wakeup(&p->p_siglist);
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msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "ktsusp", 0);
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}
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PROC_UNLOCK(p);
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}
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