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       delete_module - unload a kernel module


       int delete_module(const char *name, int flags);

       Note: No declaration of this function is provided in glibc headers; see


       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

                  *  The module is  marked  so  that  no  new  references  are

                  *  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 will fail.   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).


       On success, zero is returned.  On error, -1 is returned  and  errno  is
       set appropriately.


       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/modules_disabled in proc(5)).

              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.


       delete_module() is Linux-specific.


       The  delete_module()  system  call  is  not  supported  by  glibc.   No
       declaration is provided in glibc  headers,  but,  through  a  quirk  of
       history,  glibc does export an ABI for this system call.  Therefore, in
       order to employ this system call, it is sufficient to manually  declare
       the  interface  in  your code; alternatively, you can invoke the system
       call using syscall(2).

       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.

   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


       create_module(2),     init_module(2),     query_module(2),    lsmod(8),
       modprobe(8), rmmod(8)


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