freebsd-dev/sys/kern/kern_kthread.c

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/*
* Copyright (c) 1999 Peter Wemm <peter@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/wait.h>
#include <machine/stdarg.h>
/*
* Start a kernel process. This is called after a fork() call in
* mi_startup() in the file kern/init_main.c.
*
* This function is used to start "internal" daemons and intended
* to be called from SYSINIT().
*/
void
kproc_start(udata)
const void *udata;
{
const struct kproc_desc *kp = udata;
int error;
error = kthread_create((void (*)(void *))kp->func, NULL,
kp->global_procpp, 0, "%s", kp->arg0);
if (error)
panic("kproc_start: %s: error %d", kp->arg0, error);
}
/*
* Create a kernel process/thread/whatever. It shares its address space
* with proc0 - ie: kernel only.
*
* func is the function to start.
* arg is the parameter to pass to function on first startup.
* newpp is the return value pointing to the thread's struct proc.
* flags are flags to fork1 (in unistd.h)
* fmt and following will be *printf'd into (*newpp)->p_comm (for ps, etc.).
*/
int
kthread_create(void (*func)(void *), void *arg,
struct proc **newpp, int flags, const char *fmt, ...)
{
int error;
va_list ap;
struct proc *p2;
if (!proc0.p_stats /* || proc0.p_stats->p_start.tv_sec == 0 */)
panic("kthread_create called too soon");
error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
&p2);
if (error)
return error;
/* save a global descriptor, if desired */
if (newpp != NULL)
*newpp = p2;
/* this is a non-swapped system process */
PROC_LOCK(p2);
p2->p_flag |= P_SYSTEM | P_KTHREAD;
p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
_PHOLD(p2);
PROC_UNLOCK(p2);
/* set up arg0 for 'ps', et al */
va_start(ap, fmt);
vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, ap);
va_end(ap);
/* call the processes' main()... */
cpu_set_fork_handler(FIRST_THREAD_IN_PROC(p2), func, arg);
/* Delay putting it on the run queue until now. */
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
mtx_lock_spin(&sched_lock);
p2->p_sflag |= PS_INMEM;
if (!(flags & RFSTOPPED)) {
p2->p_stat = SRUN;
setrunqueue(FIRST_THREAD_IN_PROC(p2)); /* XXXKSE */
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
mtx_unlock_spin(&sched_lock);
return 0;
}
void
kthread_exit(int ecode)
{
struct thread *td;
struct proc *p;
td = curthread;
p = td->td_proc;
sx_xlock(&proctree_lock);
PROC_LOCK(p);
proc_reparent(p, initproc);
PROC_UNLOCK(p);
sx_xunlock(&proctree_lock);
exit1(td, W_EXITCODE(ecode, 0));
}
/*
* Advise a kernel process to suspend (or resume) in its main loop.
* Participation is voluntary.
*/
int
kthread_suspend(struct proc *p, int timo)
{
/*
* Make sure this is indeed a system process and we can safely
* use the p_siglist field.
*/
PROC_LOCK(p);
if ((p->p_flag & P_KTHREAD) == 0) {
PROC_UNLOCK(p);
return (EINVAL);
}
SIGADDSET(p->p_siglist, SIGSTOP);
wakeup(p);
return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkt", timo);
}
int
kthread_resume(struct proc *p)
{
/*
* Make sure this is indeed a system process and we can safely
* use the p_siglist field.
*/
PROC_LOCK(p);
if ((p->p_flag & P_KTHREAD) == 0) {
PROC_UNLOCK(p);
return (EINVAL);
}
SIGDELSET(p->p_siglist, SIGSTOP);
PROC_UNLOCK(p);
wakeup(&p->p_siglist);
return (0);
}
void
kthread_suspend_check(struct proc *p)
{
PROC_LOCK(p);
while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
wakeup(&p->p_siglist);
msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "ktsusp", 0);
}
PROC_UNLOCK(p);
}