330 lines
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330 lines
7.0 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of DELETE_MODULE</TITLE>
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</HEAD><BODY>
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<H1>DELETE_MODULE</H1>
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Section: Linux Programmer's Manual (2)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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delete_module - unload a kernel module
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>int delete_module(const char *</B><I>name</I><B>, int </B><I>flags</I><B>);</B>
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</PRE>
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<P>
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<I>Note</I>:
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No declaration of this system call is provided in glibc headers; see NOTES.
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>delete_module</B>()
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system call attempts to remove the unused loadable module entry
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identified by
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<I>name</I>.
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If the module has an
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<I>exit</I>
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function, then that function is executed before unloading the module.
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The
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<I>flags</I>
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argument is used to modify the behavior of the system call,
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as described below.
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This system call requires privilege.
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<P>
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Module removal is attempted according to the following rules:
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<DL COMPACT>
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<DT id="1">1.<DD>
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If there are other loaded modules that depend on
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(i.e., refer to symbols defined in) this module,
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then the call fails.
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<DT id="2">2.<DD>
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Otherwise, if the reference count for the module
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(i.e., the number of processes currently using the module)
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is zero, then the module is immediately unloaded.
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<DT id="3">3.<DD>
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If a module has a nonzero reference count,
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then the behavior depends on the bits set in
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<I>flags</I>.
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In normal usage (see NOTES), the
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<B>O_NONBLOCK</B>
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flag is always specified, and the
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<B>O_TRUNC</B>
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flag may additionally be specified.
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<DT id="4"><DD>
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The various combinations for
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<I>flags</I>
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have the following effect:
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<DL COMPACT><DT id="5"><DD>
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<DL COMPACT>
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<DT id="6"><B>flags == O_NONBLOCK</B>
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<DD>
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The call returns immediately, with an error.
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<DT id="7"><B>flags == (O_NONBLOCK | O_TRUNC)</B>
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<DD>
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The module is unloaded immediately,
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regardless of whether it has a nonzero reference count.
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<DT id="8"><B>(flags & O_NONBLOCK) == 0</B>
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<DD>
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If
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<I>flags</I>
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does not specify
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<B>O_NONBLOCK</B>,
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the following steps occur:
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<DL COMPACT><DT id="9"><DD>
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<DL COMPACT>
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<DT id="10">*<DD>
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The module is marked so that no new references are permitted.
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<DT id="11">*<DD>
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If the module's reference count is nonzero,
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the caller is placed in an uninterruptible sleep state
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(<B>TASK_UNINTERRUPTIBLE</B>)
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until the reference count is zero, at which point the call unblocks.
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<DT id="12">*<DD>
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The module is unloaded in the usual way.
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</DL>
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</DL>
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</DL>
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</DL>
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</DL>
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<P>
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The
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<B>O_TRUNC</B>
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flag has one further effect on the rules described above.
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By default, if a module has an
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<I>init</I>
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function but no
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<I>exit</I>
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function, then an attempt to remove the module fails.
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However, if
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<B>O_TRUNC</B>
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was specified, this requirement is bypassed.
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<P>
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Using the
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<B>O_TRUNC</B>
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flag is dangerous!
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If the kernel was not built with
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<B>CONFIG_MODULE_FORCE_UNLOAD</B>,
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this flag is silently ignored.
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(Normally,
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<B>CONFIG_MODULE_FORCE_UNLOAD</B>
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is enabled.)
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Using this flag taints the kernel (TAINT_FORCED_RMMOD).
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success, zero is returned.
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On error, -1 is returned and
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<I>errno</I>
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is set appropriately.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="13"><B>EBUSY</B>
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<DD>
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The module is not "live"
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(i.e., it is still being initialized or is already marked for removal);
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or, the module has
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an
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<I>init</I>
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function but has no
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<I>exit</I>
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function, and
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<B>O_TRUNC</B>
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was not specified in
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<I>flags</I>.
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<DT id="14"><B>EFAULT</B>
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<DD>
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<I>name</I>
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refers to a location outside the process's accessible address space.
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<DT id="15"><B>ENOENT</B>
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<DD>
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No module by that name exists.
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<DT id="16"><B>EPERM</B>
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<DD>
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The caller was not privileged
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(did not have the
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<B>CAP_SYS_MODULE</B>
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capability),
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or module unloading is disabled
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(see
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<I>/proc/sys/kernel/modules_disabled</I>
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in
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<B><A HREF="/cgi-bin/man/man2html?5+proc">proc</A></B>(5)).
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<DT id="17"><B>EWOULDBLOCK</B>
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<DD>
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Other modules depend on this module;
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or,
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<B>O_NONBLOCK</B>
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was specified in
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<I>flags</I>,
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but the reference count of this module is nonzero and
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<B>O_TRUNC</B>
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was not specified in
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<I>flags</I>.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>CONFORMING TO</H2>
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<B>delete_module</B>()
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is Linux-specific.
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<A NAME="lbAH"> </A>
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<H2>NOTES</H2>
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The
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<B>delete_module</B>()
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system call is not supported by glibc.
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No declaration is provided in glibc headers, but, through a quirk of history,
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glibc versions before 2.23 did export an ABI for this system call.
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Therefore, in order to employ this system call,
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it is (before glibc 2.23) sufficient to
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manually declare the interface in your code;
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alternatively, you can invoke the system call using
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<B><A HREF="/cgi-bin/man/man2html?2+syscall">syscall</A></B>(2).
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<P>
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The uninterruptible sleep that may occur if
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<B>O_NONBLOCK</B>
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is omitted from
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<I>flags</I>
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is considered undesirable, because the sleeping process is left
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in an unkillable state.
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As at Linux 3.7, specifying
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<B>O_NONBLOCK</B>
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is optional, but in future kernels it is likely to become mandatory.
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<A NAME="lbAI"> </A>
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<H3>Linux 2.4 and earlier</H3>
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In Linux 2.4 and earlier, the system call took only one argument:
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<P>
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<B> int delete_module(const char *</B><I>name</I><B>);</B>
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<P>
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If
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<I>name</I>
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is NULL, all unused modules marked auto-clean are removed.
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<P>
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Some further details of differences in the behavior of
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<B>delete_module</B>()
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in Linux 2.4 and earlier are
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<I>not</I>
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currently explained in this manual page.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+create_module">create_module</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+init_module">init_module</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+query_module">query_module</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?8+lsmod">lsmod</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+modprobe">modprobe</A></B>(8),
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<B><A HREF="/cgi-bin/man/man2html?8+rmmod">rmmod</A></B>(8)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="18"><A HREF="#lbAB">NAME</A><DD>
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<DT id="19"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="20"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="21"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="22"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="23"><A HREF="#lbAG">CONFORMING TO</A><DD>
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<DT id="24"><A HREF="#lbAH">NOTES</A><DD>
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<DL>
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<DT id="25"><A HREF="#lbAI">Linux 2.4 and earlier</A><DD>
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</DL>
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<DT id="26"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="27"><A HREF="#lbAK">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:32 GMT, March 31, 2021
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</HTML>
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