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catch up with the code.

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julian 2007-10-26 08:28:45 +00:00
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135
share/man/man9/kthread.9
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@ -29,40 +29,35 @@
.Dt KTHREAD 9
.Os
.Sh NAME
.Nm kproc_start ,
.Nm kproc_shutdown ,
.Nm kthread_create ,
.Nm kthread_start ,
.Nm kthread_shutdown ,
.Nm kthread_add ,
.Nm kthread_exit ,
.Nm kthread_resume ,
.Nm kthread_suspend ,
.Nm kthread_suspend_check
.Nd kernel threads
.Pp
.Em WARNING WARNING WARNING.. these functions have been renamed. See
.Xr kproc 9 .
.Pp
These functions will return in almost identical form but will create actual
kernel threads. In their old form they created kernel
.Em PROCESSES .
.Sh SYNOPSIS
.In sys/kthread.h
.Ft void
.Fn kproc_start "const void *udata"
.Fn kthread_start "const void *udata"
.Ft void
.Fn kproc_shutdown "void *arg" "int howto"
.Fn kthread_shutdown "void *arg" "int howto"
.Ft int
.Fn kthread_create "void (*func)(void *)" "void *arg" "struct proc **newpp" "int flags" "int pages" "const char *fmt" "..."
.Fn kthread_add "void (*func)(void *)" "void *arg" "struct proc *procp" "struct thread **newtdpp" "int flags" "int pages" "const char *fmt" "..."
.Ft void
.Fn kthread_exit "int ecode"
.Fn kthread_exit "void"
.Ft int
.Fn kthread_resume "struct proc *p"
.Fn kthread_resume "struct thread *td"
.Ft int
.Fn kthread_suspend "struct proc *p" "int timo"
.Fn kthread_suspend "struct thread *td" "int timo"
.Ft void
.Fn kthread_suspend_check "struct proc *p"
.Fn kthread_suspend_check "struct thread *td"
.Sh DESCRIPTION
The function
.Fn kproc_start
.Fn kthread_start
is used to start
.Dq internal
daemons such as bufdaemon, pagedaemon, vmdaemon, and the syncer and is intended
@ -71,43 +66,45 @@ to be called from
The
.Fa udata
argument is actually a pointer to a
.Li struct kproc_desc
.Li struct kthread_desc
which describes the kernel thread that should be created:
.Bd -literal -offset indent
struct kproc_desc {
struct kthread_desc {
char *arg0;
void (*func)(void);
struct proc **global_procpp;
struct thread **global_threadpp;
};
.Ed
.Pp
The structure members are used by
.Fn kproc_start
.Fn kthread_start
as follows:
.Bl -tag -width "global_procpp" -offset indent
.Bl -tag -width "global_threadpp" -offset indent
.It Va arg0
String to be used for the name of the process.
String to be used for the name of the thread.
This string will be copied into the
.Va p_comm
member of the new process'
.Li struct proc .
.Va td_name
member of the new threads'
.Li struct thread .
.It Va func
The main function for this kernel process to run.
.It Va global_procpp
.It Va global_threadpp
A pointer to a
.Li struct proc
pointer that should be updated to point to the newly created process' process
.Li struct thread
pointer that should be updated to point to the newly created thread' thread
structure.
If this variable is
.Dv NULL ,
then it is ignored.
then it is ignored. The thread will be a subthread of proc0 (PID 0).
.El
.Pp
The
.Fn kthread_create
.Fn kthread_add
function is used to create a kernel thread.
The new thread shares its address space with process 0, the swapper process,
and runs in kernel mode only.
The new thread runs in kernel mode only. It is added to the
process specified by the
.Fa procp
argument, or if that is NULL, to proc0.
The
.Fa func
argument specifies the function that the thread should execute.
@ -117,10 +114,10 @@ argument is an arbitrary pointer that is passed in as the only argument to
.Fa func
when it is called by the new process.
The
.Fa newpp
.Fa newtdp
pointer points to a
.Li struct proc
pointer that is to be updated to point to the newly created process.
.Li struct thread
pointer that is to be updated to point to the newly created thread.
If this argument is
.Dv NULL ,
then it is ignored.
@ -136,9 +133,9 @@ The rest of the arguments form a
.Xr printf 9
argument list that is used to build the name of the new thread and is stored
in the
.Va p_comm
.Va td_name
member of the new thread's
.Li struct proc .
.Li struct thread .
.Pp
The
.Fn kthread_exit
@ -146,13 +143,6 @@ function is used to terminate kernel threads.
It should be called by the main function of the kernel thread rather than
letting the main function return to its caller.
The
.Fa ecode
argument specifies the exit status of the thread.
While exiting, the function
.Xr exit1 9
will initiate a call to
.Xr wakeup 9
on the thread handle.
.Pp
The
.Fn kthread_resume ,
@ -164,7 +154,7 @@ During the main loop of its execution, a kernel thread that wishes to allow
itself to be suspended should call
.Fn kthread_suspend_check
passing in
.Va curproc
.Va curthread
as the only argument.
This function checks to see if the kernel thread has been asked to suspend.
If it has, it will
@ -175,9 +165,9 @@ kernel thread to continue.
The other two functions are used to notify a kernel thread of a suspend or
resume request.
The
.Fa p
.Fa td
argument points to the
.Li struct proc
.Li struct thread
of the kernel thread to suspend or resume.
For
.Fn kthread_suspend ,
@ -187,7 +177,7 @@ argument specifies a timeout to wait for the kernel thread to acknowledge the
suspend request and suspend itself.
.Pp
The
.Fn kproc_shutdown
.Fn kthread_shutdown
function is meant to be registered as a shutdown event for kernel threads that
need to be suspended voluntarily during system shutdown so as not to interfere
with system shutdown activities.
@ -195,31 +185,31 @@ The actual suspension of the kernel thread is done with
.Fn kthread_suspend .
.Sh RETURN VALUES
The
.Fn kthread_create ,
.Fn kthread_add ,
.Fn kthread_resume ,
and
.Fn kthread_suspend
functions return zero on success and non-zero on failure.
.Sh EXAMPLES
This example demonstrates the use of a
.Li struct kproc_desc
.Li struct kthread_desc
and the functions
.Fn kproc_start ,
.Fn kproc_shutdown ,
.Fn kthread_start ,
.Fn kthread_shutdown ,
and
.Fn kthread_suspend_check
to run the
.Dq bufdaemon
process.
.Bd -literal -offset indent
static struct proc *bufdaemonproc;
static struct thread *bufdaemonthread;
static struct kproc_desc buf_kp = {
static struct kthread_desc buf_kp = {
"bufdaemon",
buf_daemon,
&bufdaemonproc
&bufdaemonthread
};
SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start,
SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kthread_start,
&buf_kp)
static void
@ -229,11 +219,11 @@ buf_daemon()
/*
* This process needs to be suspended prior to shutdown sync.
*/
EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown,
bufdaemonproc, SHUTDOWN_PRI_LAST);
EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown,
bufdaemonthread, SHUTDOWN_PRI_LAST);
...
for (;;) {
kthread_suspend_check(bufdaemonproc);
kthread_suspend_check(bufdaemonthread);
...
}
}
@ -247,7 +237,7 @@ functions will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa p
.Fa td
argument does not reference a kernel thread.
.El
.Pp
@ -271,16 +261,19 @@ parameter.
.El
.Sh SEE ALSO
.Xr rfork 2 ,
.Xr kproc 9 ,
.Xr exit1 9 ,
.Xr SYSINIT 9 ,
.Xr wakeup 9
.Sh HISTORY
The
.Fn kproc_start
.Fn kthread_start
function first appeared in
.Fx 2.2 .
.Fx 2.2
where it created a whole process. It was converted to create threads in
.Fx 8.0 .
The
.Fn kproc_shutdown ,
.Fn kthread_shutdown ,
.Fn kthread_create ,
.Fn kthread_exit ,
.Fn kthread_resume ,
@ -288,11 +281,23 @@ The
and
.Fn kthread_suspend_check
functions were introduced in
.Fx 4.0 .
.Fx 4.0
and were converted to treads in
.Fx 8.0 .
The
.Fn kthread_create
call was renamed to kthread_add in
.Fx 8.0 .
The old functionality of creating a kernel process was renamed
to
.Fn kproc_create
(and friends).
See
.Xr kproc 9
Prior to
.Fx 5.0 ,
the
.Fn kproc_shutdown ,
.Fn kthread_shutdown ,
.Fn kthread_resume ,
.Fn kthread_suspend ,
and