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33 .Nm kthread_shutdown ,
38 .Nm kthread_suspend_check
43 .Fn kthread_start "const void *udata"
45 .Fn kthread_shutdown "void *arg" "int howto"
48 .Fa "void (*func)(void *)" "void *arg" "struct proc *procp"
49 .Fa "struct thread **newtdpp" "int flags" "int pages"
50 .Fa "const char *fmt" ...
53 .Fn kthread_exit "void"
55 .Fn kthread_resume "struct thread *td"
57 .Fn kthread_suspend "struct thread *td" "int timo"
59 .Fn kthread_suspend_check "struct thread *td"
66 .Nm bufdaemon , pagedaemon , vmdaemon ,
74 argument is actually a pointer to a
75 .Vt "struct kthread_desc"
76 which describes the kernel thread that should be created:
77 .Bd -literal -offset indent
81 struct thread **global_threadpp;
85 The structure members are used by
88 .Bl -tag -width ".Va global_threadpp" -offset indent
90 String to be used for the name of the thread.
91 This string will be copied into the
93 member of the new threads'
96 The main function for this kernel thread to run.
97 .It Va global_threadpp
100 pointer that should be updated to point to the newly created thread's
106 The thread will be a subthread of
113 function is used to create a kernel thread.
114 The new thread runs in kernel mode only.
115 It is added to the process specified by the
117 argument, or if that is
123 argument specifies the function that the thread should execute.
126 argument is an arbitrary pointer that is passed in as the only argument to
128 when it is called by the new thread.
133 pointer that is to be updated to point to the newly created thread.
139 argument specifies a set of flags as described in
143 argument specifies the size of the new kernel thread's stack in pages.
144 If 0 is used, the default kernel stack size is allocated.
145 The rest of the arguments form a
147 argument list that is used to build the name of the new thread and is stored
150 member of the new thread's
151 .Vt "struct thread" .
155 function is used to terminate kernel threads.
156 It should be called by the main function of the kernel thread rather than
157 letting the main function return to its caller.
158 .\" XXX "int ecode" argument isn't documented.
162 .Fn kthread_suspend ,
164 .Fn kthread_suspend_check
165 functions are used to suspend and resume a kernel thread.
166 During the main loop of its execution, a kernel thread that wishes to allow
167 itself to be suspended should call
168 .Fn kthread_suspend_check
171 as the only argument.
172 This function checks to see if the kernel thread has been asked to suspend.
175 until it is told to resume.
176 Once it has been told to resume it will return allowing execution of the
177 kernel thread to continue.
178 The other two functions are used to notify a kernel thread of a suspend or
182 argument points to the
184 of the kernel thread to suspend or resume.
186 .Fn kthread_suspend ,
189 argument specifies a timeout to wait for the kernel thread to acknowledge the
190 suspend request and suspend itself.
194 function is meant to be registered as a shutdown event for kernel threads that
195 need to be suspended voluntarily during system shutdown so as not to interfere
196 with system shutdown activities.
197 The actual suspension of the kernel thread is done with
198 .Fn kthread_suspend .
205 functions return zero on success and non-zero on failure.
207 This example demonstrates the use of a
208 .Vt "struct kthread_desc"
211 .Fn kthread_shutdown ,
213 .Fn kthread_suspend_check
217 .Bd -literal -offset indent
218 static struct thread *bufdaemonthread;
220 static struct kthread_desc buf_kp = {
225 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kthread_start,
233 * This process needs to be suspended prior to shutdown sync.
235 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown,
236 bufdaemonthread, SHUTDOWN_PRI_LAST);
239 kthread_suspend_check(bufdaemonthread);
249 functions will fail if:
254 argument does not reference a kernel thread.
259 function will fail if:
262 The system-imposed limit on the total
263 number of processes under execution would be exceeded.
264 The limit is given by the
271 flag was specified in the
284 function first appeared in
286 where it created a whole process.
287 It was converted to create threads in
290 .Fn kthread_shutdown ,
293 .Fn kthread_suspend ,
295 .Fn kthread_suspend_check
296 functions were introduced in
298 and were converted to threads in
306 The old functionality of creating a kernel process was renamed
312 .Fn kthread_shutdown ,
314 .Fn kthread_suspend ,
316 .Fn kthread_suspend_check
322 .Fn kproc_suspend_loop ,