diff options
Diffstat (limited to 'static/freebsd/man9/dev_refthread.9 3.html')
| -rw-r--r-- | static/freebsd/man9/dev_refthread.9 3.html | 125 |
1 files changed, 0 insertions, 125 deletions
diff --git a/static/freebsd/man9/dev_refthread.9 3.html b/static/freebsd/man9/dev_refthread.9 3.html deleted file mode 100644 index 9ca70fac..00000000 --- a/static/freebsd/man9/dev_refthread.9 3.html +++ /dev/null @@ -1,125 +0,0 @@ -<table class="head"> - <tr> - <td class="head-ltitle">DEV_REFTHREAD(9)</td> - <td class="head-vol">Kernel Developer's Manual</td> - <td class="head-rtitle">DEV_REFTHREAD(9)</td> - </tr> -</table> -<div class="manual-text"> -<section class="Sh"> -<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1> -<p class="Pp"><code class="Nm">dev_refthread</code>, - <code class="Nm">devvn_refthread</code>, - <code class="Nm">dev_relthread</code> — <span class="Nd">safely - access device methods</span></p> -</section> -<section class="Sh"> -<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1> -<p class="Pp"><code class="In">#include - <<a class="In">sys/param.h</a>></code> - <br/> - <code class="In">#include <<a class="In">sys/conf.h</a>></code></p> -<p class="Pp"><var class="Ft">struct cdevsw *</var> - <br/> - <code class="Fn">dev_refthread</code>(<var class="Fa" style="white-space: nowrap;">struct - cdev *dev</var>, <var class="Fa" style="white-space: nowrap;">int - *ref</var>);</p> -<p class="Pp"><var class="Ft">struct cdevsw *</var> - <br/> - <code class="Fn">devvn_refthread</code>(<var class="Fa" style="white-space: nowrap;">struct - vnode *vp</var>, <var class="Fa" style="white-space: nowrap;">struct cdev - **devp</var>, <var class="Fa" style="white-space: nowrap;">int - *ref</var>);</p> -<p class="Pp"><var class="Ft">void</var> - <br/> - <code class="Fn">dev_relthread</code>(<var class="Fa" style="white-space: nowrap;">struct - cdev *dev</var>, <var class="Fa" style="white-space: nowrap;">int - ref</var>);</p> -</section> -<section class="Sh"> -<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1> -<p class="Pp">The - <a class="permalink" href="#dev_refthread"><code class="Fn" id="dev_refthread">dev_refthread</code></a>() - (or <code class="Fn">devvn_refthread</code>()) and - <code class="Fn">dev_relthread</code>() routines provide a safe way to - access <a class="Xr">devfs(4)</a> devices that may be concurrently destroyed - by - <a class="permalink" href="#destroy_dev"><code class="Fn" id="destroy_dev">destroy_dev</code></a>() - (e.g., removable media).</p> -<p class="Pp" id="dev_refthread~2">If successful, - <a class="permalink" href="#dev_refthread~2"><code class="Fn">dev_refthread</code></a>() - and <code class="Fn">devvn_refthread</code>() acquire a "thread - reference" to the associated <var class="Vt">struct cdev</var> and - return a non-NULL pointer to the cdev's <var class="Vt">struct cdevsw</var> - method table. For the duration of that reference, the cdev's associated - private data and method table object are valid. Destruction of the cdev - sleeps until the thread reference is released.</p> -<p class="Pp" id="dev_refthread~3">A reference cannot prevent media removal. It - is an implementation detail of individual drivers how method calls from - callers with - <a class="permalink" href="#dev_refthread~3"><code class="Fn">dev_refthread</code></a>() - references are handled when the device is pending destruction. A common - behavior for disk devices is to return the <code class="Er">ENXIO</code> - status, but that is not required by this KPI.</p> -<p class="Pp" id="devvn_refthread">The - <a class="permalink" href="#devvn_refthread"><code class="Fn">devvn_refthread</code></a>() - variant of <code class="Fn">dev_refthread</code>() extracts the - <var class="Vt">struct cdev</var> pointer out of the - <code class="Dv">VCHR</code> <a class="Xr">vnode(9)</a> automatically before - performing the same actions as <code class="Fn">dev_refthread</code>(). - Additionally, a pointer to the <var class="Vt">struct cdev</var> is returned - to the caller via <var class="Fa">*devp</var>. - <code class="Fn">devvn_refthread</code>() correctly handles possible - parallel reclamation of the vnode.</p> -<p class="Pp" id="dev_relthread"><a class="permalink" href="#dev_relthread"><code class="Fn">dev_relthread</code></a>() - is used to release a reference to a <var class="Vt">struct cdev</var>. - <code class="Fn">dev_relthread</code>() - <a class="permalink" href="#must"><b class="Sy" id="must">must</b></a> only - be invoked when the associated invocation of - <code class="Fn">dev_refthread</code>() or - <code class="Fn">devvn_refthread</code>() returned a non-NULL - <var class="Vt">struct cdevsw *</var>.</p> -</section> -<section class="Sh"> -<h1 class="Sh" id="CONTEXT"><a class="permalink" href="#CONTEXT">CONTEXT</a></h1> -<p class="Pp"><var class="Vt">struct cdev</var> objects have two reference - counts, <var class="Va">si_refcount</var> and - <var class="Va">si_threadcount</var>. The - <code class="Fn">dev_refthread</code>(), - <code class="Fn">devvn_refthread</code>(), and - <code class="Fn">dev_relthread</code>() functions manipulate the - <var class="Va">si_threadcount</var>. The - <var class="Va">si_threadcount</var> reference guarantees the liveness of - the <var class="Vt">struct cdev</var> object. The other - <var class="Va">si_refcount</var> reference provides only the weaker - guarantee that the memory backing the <var class="Vt">struct cdev</var> has - not been freed.</p> -</section> -<section class="Sh"> -<h1 class="Sh" id="RETURN_VALUES"><a class="permalink" href="#RETURN_VALUES">RETURN - VALUES</a></h1> -<p class="Pp">If <code class="Fn">dev_refthread</code>() or - <code class="Fn">devvn_refthread</code>() are unsuccessful, they return - <code class="Dv">NULL</code>.</p> -<div class="Bf Em">If these routines are unsuccessful, they do not increment the - <var class="Vt">struct cdev</var> <var class="Va">si_threadcount</var> and do - not initialize the value pointed to by the <var class="Fa">*ref</var> - parameter in any way.</div> -</section> -<section class="Sh"> -<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE - ALSO</a></h1> -<p class="Pp"><a class="Xr">devfs(4)</a>, <a class="Xr">destroy_dev(9)</a></p> -</section> -<section class="Sh"> -<h1 class="Sh" id="CAVEATS"><a class="permalink" href="#CAVEATS">CAVEATS</a></h1> -<p class="Pp">Do not invoke <code class="Fn">dev_relthread</code>() unless the - matching refthread routine succeeded!</p> -</section> -</div> -<table class="foot"> - <tr> - <td class="foot-date">August 29, 2018</td> - <td class="foot-os">FreeBSD 15.0</td> - </tr> -</table> |