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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"
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 "void"
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" "..."
72 functions was renamed to be the
75 as they were previously misnamed
76 and actually produced kernel processes.
79 functions was added to produce
84 man page for more information on the renamed calls.
86 .Fn kproc_kthread_add 9
87 function appears in both pages as its functionality is split.
94 .Nm bufdaemon , pagedaemon , vmdaemon ,
102 argument is actually a pointer to a
103 .Vt "struct kthread_desc"
104 which describes the kernel thread that should be created:
105 .Bd -literal -offset indent
106 struct kthread_desc {
109 struct thread **global_threadpp;
113 The structure members are used by
116 .Bl -tag -width ".Va global_threadpp" -offset indent
118 String to be used for the name of the thread.
119 This string will be copied into the
121 member of the new threads'
122 .Vt "struct thread" .
124 The main function for this kernel thread to run.
125 .It Va global_threadpp
128 pointer that should be updated to point to the newly created thread's
134 The thread will be a subthread of
141 function is used to create a kernel thread.
142 The new thread runs in kernel mode only.
143 It is added to the process specified by the
145 argument, or if that is
151 argument specifies the function that the thread should execute.
154 argument is an arbitrary pointer that is passed in as the only argument to
156 when it is called by the new thread.
161 pointer that is to be updated to point to the newly created thread.
167 argument may be set to
169 to leave the thread in a stopped state.
175 argument specifies the size of the new kernel thread's stack in pages.
176 If 0 is used, the default kernel stack size is allocated.
177 The rest of the arguments form a
179 argument list that is used to build the name of the new thread and is stored
182 member of the new thread's
183 .Vt "struct thread" .
186 .Fn kproc_kthread_add
187 function is much like the
189 function above except that if the kproc does not already
190 exist, it is created.
191 This function is better documented in the
197 function is used to terminate kernel threads.
198 It should be called by the main function of the kernel thread rather than
199 letting the main function return to its caller.
200 .\" XXX "int ecode" argument isn't documented.
204 .Fn kthread_suspend ,
206 .Fn kthread_suspend_check
207 functions are used to suspend and resume a kernel thread.
208 During the main loop of its execution, a kernel thread that wishes to allow
209 itself to be suspended should call
210 .Fn kthread_suspend_check
211 in order to check if the it has been asked to suspend.
214 until it is told to resume.
215 Once it has been told to resume it will return allowing execution of the
216 kernel thread to continue.
217 The other two functions are used to notify a kernel thread of a suspend or
221 argument points to the
223 of the kernel thread to suspend or resume.
225 .Fn kthread_suspend ,
228 argument specifies a timeout to wait for the kernel thread to acknowledge the
229 suspend request and suspend itself.
233 function is meant to be registered as a shutdown event for kernel threads that
234 need to be suspended voluntarily during system shutdown so as not to interfere
235 with system shutdown activities.
236 The actual suspension of the kernel thread is done with
237 .Fn kthread_suspend .
244 functions return zero on success and non-zero on failure.
246 This example demonstrates the use of a
247 .Vt "struct kthread_desc"
250 .Fn kthread_shutdown ,
252 .Fn kthread_suspend_check
256 .Bd -literal -offset indent
257 static struct thread *bufdaemonthread;
259 static struct kthread_desc buf_kp = {
264 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kthread_start,
272 * This process needs to be suspended prior to shutdown sync.
274 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown,
275 bufdaemonthread, SHUTDOWN_PRI_LAST);
278 kthread_suspend_check();
288 functions will fail if:
293 argument does not reference a kernel thread.
298 function will fail if:
301 Memory for a thread's stack could not be allocated.
310 function first appeared in
312 where it created a whole process.
313 It was converted to create threads in
316 .Fn kthread_shutdown ,
319 .Fn kthread_suspend ,
321 .Fn kthread_suspend_check
322 functions were introduced in
324 and were converted to threads in
332 The old functionality of creating a kernel process was renamed
338 .Fn kthread_shutdown ,
340 .Fn kthread_suspend ,
342 .Fn kthread_suspend_check
348 .Fn kproc_suspend_loop ,