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<title>pthread_mutexattr_setkind_np()--Set Mutex Kind Attribute</title>
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<h2>pthread_mutexattr_setkind_np()--Set Mutex Kind Attribute</h2>
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<br>
&nbsp;&nbsp;Syntax:
<pre> #include &lt;pthread.h&gt;
int pthread_mutexattr_setkind_np(pthread_mutexattr_t *attr,
int kind);</pre>
&nbsp;&nbsp;Service Program Name: QP0WPTHR<br>
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&nbsp;&nbsp;Default Public Authority: *USE <br>
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&nbsp;&nbsp;Threadsafe: Yes<br>
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&nbsp;&nbsp;Signal Safe: Yes<br>
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<p>The <strong>pthread_mutexattr_setkind_np</strong>() function sets the <em>kind</em> attribute in the mutex attributes object specified by <em>attr</em>. The mutex kind attribute is used to create mutexes with different behaviors.</p>
<p>The <em>kind</em> set may be one of <strong>PTHREAD_MUTEX_NONRECURSIVE_NP</strong> or <strong>PTHREAD_MUTEX_RECURSIVE_NP</strong>.</p>
<p>A recursive mutex can be locked repeatedly by the owner. The mutex does not become unlocked until the owner has called <strong>pthread_mutex_unlock</strong>() for each successful lock request that it has outstanding on the mutes. The maximum number of recursive locks by the owning thread is 32,767.</p>
<p><strong>Note:</strong> This function is not portable</p>
<br>
<h3>Authorities and Locks</h3>
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>attr</strong></dt>
<dd>(Input) Address of the mutex attributes object</dd>
<dt><strong>kind</strong></dt>
<dd>(Input) Variable containing the <em>kind</em> attribute.</dd>
</dl>
<br>
<h3>Return Value</h3>
<dl>
<dt><strong>0</strong></dt>
<dd><strong>pthread_mutexattr_setkind_np</strong>() was successful.</dd>
<dt><strong>value</strong></dt>
<dd><strong>pthread_mutexattr_setkind_np</strong>() was not successful. <em>value</em> is set to indicate the error condition.</dd>
</dl>
<br>
<h3>Error Conditions</h3>
<p>If <strong>pthread_mutexattr_setkind_np</strong>() was not successful, the error condition returned usually indicates one of the following errors. Under some conditions, the value returned could indicate an error other than those listed here.</p>
<dl>
<dt><em>[EINVAL]</em></dt>
<dd><p>The value specified for the argument is not correct.</p></dd>
</dl>
<br>
<h3>Related Information</h3>
<ul>
<li>The &lt;<strong>pthread.h</strong>> header file. See <a href="rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
<li><a href="users_50.htm">pthread_mutexattr_getkind_np()</a>--Get Mutex Kind Attribute<br><br></li>
<li><a href="users_61.htm">pthread_mutex_init()</a>--Initialize Mutex</li>
</ul>
<br>
<h3>Example</h3>
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
for information pertaining to code examples.</p>
<pre>#include &lt;pthread.h&gt;
#include &lt;stdio.h&gt;
#include &quot;check.h&quot;
void showKind(pthread_mutexattr_t *mta) {
int rc;
int kind;
printf(&quot;Check kind attribute\n&quot;);
rc = pthread_mutexattr_getkind_np(mta, &amp;kind);
checkResults(&quot;pthread_mutexattr_getpshared()\n&quot;, rc);
printf(&quot;The pshared attributed is: &quot;);
switch (kind) {
case PTHREAD_MUTEX_NONRECURSIVE_NP:
printf(&quot;PTHREAD_MUTEX_NONRECURSIVE_NP\n&quot;);
break;
case PTHREAD_MUTEX_RECURSIVE_NP:
printf(&quot;PTHREAD_MUTEX_RECURSIVE_NP\n&quot;);
break;
default :
printf(&quot;! kind Error kind=%d !\n&quot;, kind);
exit(1);
}
return;
}
int main(int argc, char **argv)
{
int rc=0;
pthread_mutexattr_t mta;
int pshared=0;
printf(&quot;Enter Testcase - %s\n&quot;, argv[0]);
printf(&quot;Create a default mutex attribute\n&quot;);
rc = pthread_mutexattr_init(&amp;mta);
checkResults(&quot;pthread_mutexattr_init()\n&quot;, rc);
showKind(&amp;mta);
printf(&quot;Change mutex kind attribute\n&quot;);
rc = pthread_mutexattr_setkind_np(&amp;mta, PTHREAD_MUTEX_RECURSIVE_NP);
checkResults(&quot;pthread_mutexattr_setkind()\n&quot;, rc);
showKind(&amp;mta);
printf(&quot;Destroy mutex attribute\n&quot;);
rc = pthread_mutexattr_destroy(&amp;mta);
checkResults(&quot;pthread_mutexattr_destroy()\n&quot;, rc);
printf(&quot;Main completed\n&quot;);
return 0;
}</pre>
<p><strong>Output:</strong></p>
<pre>Enter Testcase - QP0WTEST/TPMTXAKN0
Create a default mutex attribute
Check kind attribute
The pshared attributed is:
PTHREAD_MUTEX_NONRECURSIVE_NP
Change mutex kind attribute
Check kind attribute
The pshared attributed is:
PTHREAD_MUTEX_RECURSIVE_NP
Destroy mutex attribute
Main completed</pre>
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API introduced: V4R3
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