delete_module(2) - Linux manual page (original) (raw)
deletemodule(2) System Calls Manual deletemodule(2)
NAME top
delete_module - unload a kernel moduleLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#include <fcntl.h>** /* Definition of **O_*** constants */
**#include <sys/syscall.h>** /* Definition of **SYS_*** constants */
**#include <unistd.h>**
**int syscall(SYS_delete_module, const char ***_name_**, unsigned int** _flags_**);**
_Note_: glibc provides no wrapper for **delete_module**(), necessitating
the use of [syscall(2)](../man2/syscall.2.html).DESCRIPTION top
The **delete_module**() system call attempts to remove the unused
loadable module entry identified by _name_. If the module has an
_exit_ function, then that function is executed before unloading the
module. The _flags_ argument is used to modify the behavior of the
system call, as described below. This system call requires
privilege.
Module removal is attempted according to the following rules:
(1) If there are other loaded modules that depend on (i.e., refer
to symbols defined in) this module, then the call fails.
(2) Otherwise, if the reference count for the module (i.e., the
number of processes currently using the module) is zero, then
the module is immediately unloaded.
(3) If a module has a nonzero reference count, then the behavior
depends on the bits set in _flags_. In normal usage (see
NOTES), the **O_NONBLOCK** flag is always specified, and the
**O_TRUNC** flag may additionally be specified.
The various combinations for _flags_ have the following effect:
**flags == O_NONBLOCK**
The call returns immediately, with an error.
**flags == (O_NONBLOCK | O_TRUNC)**
The module is unloaded immediately, regardless of
whether it has a nonzero reference count.
**(flags & O_NONBLOCK) == 0**
If _flags_ does not specify **O_NONBLOCK**, the following
steps occur:
• The module is marked so that no new references are
permitted.
• If the module's reference count is nonzero, the
caller is placed in an uninterruptible sleep state
(**TASK_UNINTERRUPTIBLE**) until the reference count is
zero, at which point the call unblocks.
• The module is unloaded in the usual way.
The **O_TRUNC** flag has one further effect on the rules described
above. By default, if a module has an _init_ function but no _exit_
function, then an attempt to remove the module fails. However, if
**O_TRUNC** was specified, this requirement is bypassed.
Using the **O_TRUNC** flag is dangerous! If the kernel was not built
with **CONFIG_MODULE_FORCE_UNLOAD**, this flag is silently ignored.
(Normally, **CONFIG_MODULE_FORCE_UNLOAD** is enabled.) Using this
flag taints the kernel (TAINT_FORCED_RMMOD).RETURN VALUE top
On success, zero is returned. On error, -1 is returned and _[errno](../man3/errno.3.html)_
is set to indicate the error.ERRORS top
**EBUSY** The module is not "live" (i.e., it is still being
initialized or is already marked for removal); or, the
module has an _init_ function but has no _exit_ function, and
**O_TRUNC** was not specified in _flags_.
**EFAULT** _name_ refers to a location outside the process's accessible
address space.
**ENOENT** No module by that name exists.
**EPERM** The caller was not privileged (did not have the
**CAP_SYS_MODULE** capability), or module unloading is disabled
(see _/proc/sys/kernel/modulesdisabled_ in [proc(5)](../man5/proc.5.html)).
**EWOULDBLOCK**
Other modules depend on this module; or, **O_NONBLOCK** was
specified in _flags_, but the reference count of this module
is nonzero and **O_TRUNC** was not specified in _flags_.STANDARDS top
Linux.HISTORY top
The **delete_module**() system call is not supported by glibc. No
declaration is provided in glibc headers, but, through a quirk of
history, glibc versions before glibc 2.23 did export an ABI for
this system call. Therefore, in order to employ this system call,
it is (before glibc 2.23) sufficient to manually declare the
interface in your code; alternatively, you can invoke the system
call using [syscall(2)](../man2/syscall.2.html).Linux 2.4 and earlier In Linux 2.4 and earlier, the system call took only one argument:
**int delete_module(const char ***_name_**);**
If _name_ is NULL, all unused modules marked auto-clean are removed.
Some further details of differences in the behavior of
**delete_module**() in Linux 2.4 and earlier are _not_ currently
explained in this manual page.NOTES top
The uninterruptible sleep that may occur if **O_NONBLOCK** is omitted
from _flags_ is considered undesirable, because the sleeping process
is left in an unkillable state. As at Linux 3.7, specifying
**O_NONBLOCK** is optional, but in future kernels it is likely to
become mandatory.SEE ALSO top
[create_module(2)](../man2/create%5Fmodule.2.html), [init_module(2)](../man2/init%5Fmodule.2.html), [query_module(2)](../man2/query%5Fmodule.2.html), [lsmod(8)](../man8/lsmod.8.html),
[modprobe(8)](../man8/modprobe.8.html), [rmmod(8)](../man8/rmmod.8.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-07-23 deletemodule(2)
Pages that refer to this page:create_module(2), get_kernel_syms(2), init_module(2), query_module(2), syscalls(2), unimplemented(2), systemd.exec(5), capabilities(7)