xref: /xnu-10002.61.3/osfmk/man/thread_suspend.html (revision 0f4c859e951fba394238ab619495c4e1d54d0f34)
1*0f4c859eSApple OSS Distributions<h2>thread_suspend</h2>
2*0f4c859eSApple OSS Distributions<hr>
3*0f4c859eSApple OSS Distributions<p>
4*0f4c859eSApple OSS Distributions<strong>Function</strong> - Suspend a thread.
5*0f4c859eSApple OSS Distributions<h3>SYNOPSIS</h3>
6*0f4c859eSApple OSS Distributions<pre>
7*0f4c859eSApple OSS Distributions<strong>kern_return_t   thread_suspend</strong>
8*0f4c859eSApple OSS Distributions                <strong>(thread_act_t</strong>                     <var>target_thread</var><strong>);</strong>
9*0f4c859eSApple OSS Distributions</pre>
10*0f4c859eSApple OSS Distributions<h3>PARAMETERS</h3>
11*0f4c859eSApple OSS Distributions<dl>
12*0f4c859eSApple OSS Distributions<p>
13*0f4c859eSApple OSS Distributions<dt> <var>target_thread</var>
14*0f4c859eSApple OSS Distributions<dd>
15*0f4c859eSApple OSS Distributions[in thread send right]
16*0f4c859eSApple OSS DistributionsThe thread to be suspended.
17*0f4c859eSApple OSS Distributions</dl>
18*0f4c859eSApple OSS Distributions<h3>DESCRIPTION</h3>
19*0f4c859eSApple OSS Distributions<p>
20*0f4c859eSApple OSS DistributionsThe <strong>thread_suspend</strong> function increments the suspend
21*0f4c859eSApple OSS Distributionscount for <var>target_thread</var>
22*0f4c859eSApple OSS Distributionsand prevents the thread from executing any more user-level instructions.
23*0f4c859eSApple OSS Distributions<p>
24*0f4c859eSApple OSS DistributionsIn this context, a user-level instruction can be either a machine instruction
25*0f4c859eSApple OSS Distributionsexecuted in user mode or a system trap instruction, including
26*0f4c859eSApple OSS Distributionsa page fault.  If a
27*0f4c859eSApple OSS Distributionsthread is currently executing within a system trap, the kernel
28*0f4c859eSApple OSS Distributionscode may continue
29*0f4c859eSApple OSS Distributionsto execute until it reaches the system return code or it may
30*0f4c859eSApple OSS Distributionssuspend within the
31*0f4c859eSApple OSS Distributionskernel code.  In either case, the system trap returns when the thread resumes.
32*0f4c859eSApple OSS Distributions<p>
33*0f4c859eSApple OSS DistributionsTo resume a suspended thread, use <strong>thread_resume</strong>.  If
34*0f4c859eSApple OSS Distributionsthe suspend count is
35*0f4c859eSApple OSS Distributionsgreater than one, <strong>thread_resume</strong> must be repeated that
36*0f4c859eSApple OSS Distributionsnumber of times.
37*0f4c859eSApple OSS Distributions<h3>CAUTIONS</h3>
38*0f4c859eSApple OSS Distributions<p>
39*0f4c859eSApple OSS DistributionsUnpredictable results may occur if a program suspends a thread and alters its
40*0f4c859eSApple OSS Distributionsuser state so that its direction is changed upon resuming.  Note that the
41*0f4c859eSApple OSS Distributions<strong>thread_abort</strong> function allows a system call to be aborted
42*0f4c859eSApple OSS Distributionsonly if it is progressing in a
43*0f4c859eSApple OSS Distributionspredictable way.
44*0f4c859eSApple OSS Distributions<h3>RETURN VALUES</h3>
45*0f4c859eSApple OSS Distributions<p>
46*0f4c859eSApple OSS DistributionsOnly generic errors apply.
47*0f4c859eSApple OSS Distributions<h3>RELATED INFORMATION</h3>
48*0f4c859eSApple OSS Distributions<p>
49*0f4c859eSApple OSS DistributionsFunctions:
50*0f4c859eSApple OSS Distributions<a href="task_resume.html"><strong>task_resume</strong></a>,
51*0f4c859eSApple OSS Distributions<a href="task_suspend.html"><strong>task_suspend</strong></a>,
52*0f4c859eSApple OSS Distributions<a href="thread_abort.html"><strong>thread_abort</strong></a>,
53*0f4c859eSApple OSS Distributions<a href="thread_get_state.html"><strong>thread_get_state</strong></a>,
54*0f4c859eSApple OSS Distributions<a href="thread_info.html"><strong>thread_info</strong></a>,
55*0f4c859eSApple OSS Distributions<a href="thread_resume.html"><strong>thread_resume</strong></a>,
56*0f4c859eSApple OSS Distributions<a href="thread_set_state.html"><strong>thread_set_state</strong></a>,
57*0f4c859eSApple OSS Distributions<a href="thread_terminate.html"><strong>thread_terminate</strong></a>.
58