freebsd-dev/sys/kern/kern_kthread.c
John Baldwin fd05807822 - Properly initialize the base priority (td_base_pri) of thread0 to PVM
to match the desired priority in td_priority.  Otherwise the first time
  thread0 used a borrowed priority it would drop down to PUSER instead of
  PVM.
- Explicitly initialize the starting priority of new kprocs to PVM to
  avoid inheriting some random priority from thread0.

MFC after:	2 weeks
2011-01-06 22:26:00 +00:00

458 lines
11 KiB
C

/*-
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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/rwlock.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/wait.h>
#include <sys/sched.h>
#include <vm/vm.h>
#include <vm/vm_extern.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 = kproc_create((void (*)(void *))kp->func, NULL,
kp->global_procpp, 0, 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
kproc_create(void (*func)(void *), void *arg,
struct proc **newpp, int flags, int pages, const char *fmt, ...)
{
int error;
va_list ap;
struct thread *td;
struct proc *p2;
if (!proc0.p_stats)
panic("kproc_create called too soon");
error = fork1(&thread0, RFMEM | RFFDG | RFPROC | RFSTOPPED | flags,
pages, &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);
td = FIRST_THREAD_IN_PROC(p2);
p2->p_flag |= P_SYSTEM | P_KTHREAD;
td->td_pflags |= TDP_KTHREAD;
mtx_lock(&p2->p_sigacts->ps_mtx);
p2->p_sigacts->ps_flag |= PS_NOCLDWAIT;
mtx_unlock(&p2->p_sigacts->ps_mtx);
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);
/* set up arg0 for 'ps', et al */
va_start(ap, fmt);
vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
va_end(ap);
/* call the processes' main()... */
cpu_set_fork_handler(td, func, arg);
thread_lock(td);
TD_SET_CAN_RUN(td);
sched_prio(td, PVM);
sched_user_prio(td, PUSER);
/* Delay putting it on the run queue until now. */
if (!(flags & RFSTOPPED))
sched_add(td, SRQ_BORING);
thread_unlock(td);
return 0;
}
void
kproc_exit(int ecode)
{
struct thread *td;
struct proc *p;
td = curthread;
p = td->td_proc;
/*
* Reparent curthread from proc0 to init so that the zombie
* is harvested.
*/
sx_xlock(&proctree_lock);
PROC_LOCK(p);
proc_reparent(p, initproc);
PROC_UNLOCK(p);
sx_xunlock(&proctree_lock);
/*
* Wakeup anyone waiting for us to exit.
*/
wakeup(p);
/* Buh-bye! */
exit1(td, W_EXITCODE(ecode, 0));
}
/*
* Advise a kernel process to suspend (or resume) in its main loop.
* Participation is voluntary.
*/
int
kproc_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, "suspkp", timo);
}
int
kproc_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
kproc_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, "kpsusp", 0);
}
PROC_UNLOCK(p);
}
/*
* Start a kernel thread.
*
* This function is used to start "internal" daemons and intended
* to be called from SYSINIT().
*/
void
kthread_start(udata)
const void *udata;
{
const struct kthread_desc *kp = udata;
int error;
error = kthread_add((void (*)(void *))kp->func, NULL,
NULL, kp->global_threadpp, 0, 0, "%s", kp->arg0);
if (error)
panic("kthread_start: %s: error %d", kp->arg0, error);
}
/*
* Create a kernel thread. 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.
* newtdp is the return value pointing to the thread's struct thread.
* ** XXX fix this --> flags are flags to fork1 (in unistd.h)
* fmt and following will be *printf'd into (*newtd)->td_name (for ps, etc.).
*/
int
kthread_add(void (*func)(void *), void *arg, struct proc *p,
struct thread **newtdp, int flags, int pages, const char *fmt, ...)
{
va_list ap;
struct thread *newtd, *oldtd;
if (!proc0.p_stats)
panic("kthread_add called too soon");
/* If no process supplied, put it on proc0 */
if (p == NULL) {
p = &proc0;
oldtd = &thread0;
} else {
oldtd = FIRST_THREAD_IN_PROC(p);
}
/* Initialize our new td */
newtd = thread_alloc(pages);
if (newtd == NULL)
return (ENOMEM);
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
/* XXX check if we should zero. */
bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
/* set up arg0 for 'ps', et al */
va_start(ap, fmt);
vsnprintf(newtd->td_name, sizeof(newtd->td_name), fmt, ap);
va_end(ap);
newtd->td_proc = p; /* needed for cpu_set_upcall */
/* XXX optimise this probably? */
/* On x86 (and probably the others too) it is way too full of junk */
/* Needs a better name */
cpu_set_upcall(newtd, oldtd);
/* put the designated function(arg) as the resume context */
cpu_set_fork_handler(newtd, func, arg);
newtd->td_pflags |= TDP_KTHREAD;
newtd->td_ucred = crhold(p->p_ucred);
/* this code almost the same as create_thread() in kern_thr.c */
PROC_LOCK(p);
p->p_flag |= P_HADTHREADS;
newtd->td_sigmask = oldtd->td_sigmask; /* XXX dubious */
thread_link(newtd, p);
thread_lock(oldtd);
/* let the scheduler know about these things. */
sched_fork_thread(oldtd, newtd);
TD_SET_CAN_RUN(newtd);
thread_unlock(oldtd);
PROC_UNLOCK(p);
tidhash_add(newtd);
/* Delay putting it on the run queue until now. */
if (!(flags & RFSTOPPED)) {
thread_lock(newtd);
sched_add(newtd, SRQ_BORING);
thread_unlock(newtd);
}
if (newtdp)
*newtdp = newtd;
return 0;
}
void
kthread_exit(void)
{
struct proc *p;
p = curthread->td_proc;
/* A module may be waiting for us to exit. */
wakeup(curthread);
/*
* The last exiting thread in a kernel process must tear down
* the whole process.
*/
rw_wlock(&tidhash_lock);
PROC_LOCK(p);
if (p->p_numthreads == 1) {
PROC_UNLOCK(p);
rw_wunlock(&tidhash_lock);
kproc_exit(0);
}
LIST_REMOVE(curthread, td_hash);
rw_wunlock(&tidhash_lock);
PROC_SLOCK(p);
thread_exit();
}
/*
* Advise a kernel process to suspend (or resume) in its main loop.
* Participation is voluntary.
*/
int
kthread_suspend(struct thread *td, int timo)
{
struct proc *p;
p = td->td_proc;
/*
* td_pflags should not be read by any thread other than
* curthread, but as long as this flag is invariant during the
* thread's lifetime, it is OK to check its state.
*/
if ((td->td_pflags & TDP_KTHREAD) == 0)
return (EINVAL);
/*
* The caller of the primitive should have already checked that the
* thread is up and running, thus not being blocked by other
* conditions.
*/
PROC_LOCK(p);
thread_lock(td);
td->td_flags |= TDF_KTH_SUSP;
thread_unlock(td);
return (msleep(&td->td_flags, &p->p_mtx, PPAUSE | PDROP, "suspkt",
timo));
}
/*
* Resume a thread previously put asleep with kthread_suspend().
*/
int
kthread_resume(struct thread *td)
{
struct proc *p;
p = td->td_proc;
/*
* td_pflags should not be read by any thread other than
* curthread, but as long as this flag is invariant during the
* thread's lifetime, it is OK to check its state.
*/
if ((td->td_pflags & TDP_KTHREAD) == 0)
return (EINVAL);
PROC_LOCK(p);
thread_lock(td);
td->td_flags &= ~TDF_KTH_SUSP;
thread_unlock(td);
wakeup(&td->td_flags);
PROC_UNLOCK(p);
return (0);
}
/*
* Used by the thread to poll as to whether it should yield/sleep
* and notify the caller that is has happened.
*/
void
kthread_suspend_check()
{
struct proc *p;
struct thread *td;
td = curthread;
p = td->td_proc;
if ((td->td_pflags & TDP_KTHREAD) == 0)
panic("%s: curthread is not a valid kthread", __func__);
/*
* As long as the double-lock protection is used when accessing the
* TDF_KTH_SUSP flag, synchronizing the read operation via proc mutex
* is fine.
*/
PROC_LOCK(p);
while (td->td_flags & TDF_KTH_SUSP) {
wakeup(&td->td_flags);
msleep(&td->td_flags, &p->p_mtx, PPAUSE, "ktsusp", 0);
}
PROC_UNLOCK(p);
}
int
kproc_kthread_add(void (*func)(void *), void *arg,
struct proc **procptr, struct thread **tdptr,
int flags, int pages, const char *procname, const char *fmt, ...)
{
int error;
va_list ap;
char buf[100];
struct thread *td;
if (*procptr == 0) {
error = kproc_create(func, arg,
procptr, flags, pages, "%s", procname);
if (error)
return (error);
td = FIRST_THREAD_IN_PROC(*procptr);
if (tdptr)
*tdptr = td;
va_start(ap, fmt);
vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
va_end(ap);
return (0);
}
va_start(ap, fmt);
vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
error = kthread_add(func, arg, *procptr,
tdptr, flags, pages, "%s", buf);
return (error);
}