1 .\" Copyright (c) 2000-2001
2 .\" The Regents of the University of California. All rights reserved.
4 .\" All rights reserved.
6 .\" Redistribution and use in source and binary forms, with or without
7 .\" modification, are permitted provided that the following conditions
9 .\" 1. Redistributions of source code must retain the above copyright
10 .\" notice, this list of conditions and the following disclaimer.
11 .\" 2. Redistributions in binary form must reproduce the above copyright
12 .\" notice, this list of conditions and the following disclaimer in the
13 .\" documentation and/or other materials provided with the distribution.
15 .\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
16 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 .\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
19 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 .Nm kthread_shutdown ,
38 .Nm kthread_suspend_check
43 .Fn kthread_start "const void *udata"
45 .Fn kthread_shutdown "void *arg" "int howto"
47 .Fn kthread_exit "void"
49 .Fn kthread_resume "struct thread *td"
51 .Fn kthread_suspend "struct thread *td" "int timo"
53 .Fn kthread_suspend_check "struct thread *td"
57 .Fa "void (*func)(void *)" "void *arg" "struct proc *procp"
58 .Fa "struct thread **newtdpp" "int flags" "int pages"
59 .Fa "const char *fmt" ...
63 .Fa "void (*func)(void *)" "void *arg"
64 .Fa "struct proc **procptr" "struct thread **tdptr"
65 .Fa "int flags" "int pages" "char * procname" "const char *fmt" "..."
73 .Nm bufdaemon , pagedaemon , vmdaemon ,
81 argument is actually a pointer to a
82 .Vt "struct kthread_desc"
83 which describes the kernel thread that should be created:
84 .Bd -literal -offset indent
88 struct thread **global_threadpp;
92 The structure members are used by
95 .Bl -tag -width ".Va global_threadpp" -offset indent
97 String to be used for the name of the thread.
98 This string will be copied into the
100 member of the new threads'
101 .Vt "struct thread" .
103 The main function for this kernel thread to run.
104 .It Va global_threadpp
107 pointer that should be updated to point to the newly created thread's
113 The thread will be a subthread of
120 function is used to create a kernel thread.
121 The new thread runs in kernel mode only.
122 It is added to the process specified by the
124 argument, or if that is
130 argument specifies the function that the thread should execute.
133 argument is an arbitrary pointer that is passed in as the only argument to
135 when it is called by the new thread.
140 pointer that is to be updated to point to the newly created thread.
146 argument may be set to
148 to leave the thread in a stopped state.
154 argument specifies the size of the new kernel thread's stack in pages.
155 If 0 is used, the default kernel stack size is allocated.
156 The rest of the arguments form a
158 argument list that is used to build the name of the new thread and is stored
161 member of the new thread's
162 .Vt "struct thread" .
165 .Fn kproc_kthread_add
166 function is much like the
168 function above except that if the kproc does not already
169 exist, it is created.
170 This function is better documented in the
176 function is used to terminate kernel threads.
177 It should be called by the main function of the kernel thread rather than
178 letting the main function return to its caller.
179 .\" XXX "int ecode" argument isn't documented.
183 .Fn kthread_suspend ,
185 .Fn kthread_suspend_check
186 functions are used to suspend and resume a kernel thread.
187 During the main loop of its execution, a kernel thread that wishes to allow
188 itself to be suspended should call
189 .Fn kthread_suspend_check
192 as the only argument.
193 This function checks to see if the kernel thread has been asked to suspend.
196 until it is told to resume.
197 Once it has been told to resume it will return allowing execution of the
198 kernel thread to continue.
199 The other two functions are used to notify a kernel thread of a suspend or
203 argument points to the
205 of the kernel thread to suspend or resume.
207 .Fn kthread_suspend ,
210 argument specifies a timeout to wait for the kernel thread to acknowledge the
211 suspend request and suspend itself.
215 function is meant to be registered as a shutdown event for kernel threads that
216 need to be suspended voluntarily during system shutdown so as not to interfere
217 with system shutdown activities.
218 The actual suspension of the kernel thread is done with
219 .Fn kthread_suspend .
226 functions return zero on success and non-zero on failure.
228 This example demonstrates the use of a
229 .Vt "struct kthread_desc"
232 .Fn kthread_shutdown ,
234 .Fn kthread_suspend_check
238 .Bd -literal -offset indent
239 static struct thread *bufdaemonthread;
241 static struct kthread_desc buf_kp = {
246 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kthread_start,
254 * This process needs to be suspended prior to shutdown sync.
256 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown,
257 bufdaemonthread, SHUTDOWN_PRI_LAST);
260 kthread_suspend_check(bufdaemonthread);
270 functions will fail if:
275 argument does not reference a kernel thread.
280 function will fail if:
283 Memory for a thread's stack could not be allocated.
292 function first appeared in
294 where it created a whole process.
295 It was converted to create threads in
298 .Fn kthread_shutdown ,
301 .Fn kthread_suspend ,
303 .Fn kthread_suspend_check
304 functions were introduced in
306 and were converted to threads in
314 The old functionality of creating a kernel process was renamed
320 .Fn kthread_shutdown ,
322 .Fn kthread_suspend ,
324 .Fn kthread_suspend_check
330 .Fn kproc_suspend_loop ,