Bug 391839 – compiling external module which is using file_operations fails

• Product: Gentoo Linux
• Status: UNCONFIRMED ---

[Description Alexander Zubkov 2011-11-25 08:09:59 UTC]

I'm trying to compile zfsonlinux (https://github.com/zfsonlinux) with gentoo hardened kernel and compilation fails:

  CC [M]  /home/user/soft/spl/module/spl/../../module/spl/spl-module.o
/home/user/soft/spl/module/spl/../../module/spl/spl-module.c: In function ‘__ddi_create_minor_node’:
/home/user/soft/spl/module/spl/../../module/spl/spl-module.c:124:2: error: assignment of read-only location ‘*fops’
/home/user/soft/spl/module/spl/../../module/spl/spl-module.c:126:3: error: assignment of read-only location ‘*fops’
/home/user/soft/spl/module/spl/../../module/spl/spl-module.c:128:3: error: assignment of read-only location ‘*fops’
make[5]: *** [/home/user/soft/spl/module/spl/../../module/spl/spl-module.o] Error 1
make[4]: *** [/home/user/soft/spl/module/spl] Error 2
make[3]: *** [_module_/home/user/soft/spl/module] Error 2

Cut of failed code from spl-module.c:

    92  int
    93  __ddi_create_minor_node(dev_info_t *di, char *name, int spec_type,
    94                          minor_t minor_num, char *node_type,
    95                          int flags, struct module *mod)
    96  {
    97          struct cdev *cdev;
    98          struct cb_ops *cb_ops;
    99          struct file_operations *fops;
   100          int rc;
   101          SENTRY;
...
   123          /* Setup the fops to cb_ops mapping */
   124          fops->owner = mod;
   125          if (cb_ops->cb_ioctl) {
   126                  fops->unlocked_ioctl = mod_generic_unlocked_ioctl;
   127  #ifdef CONFIG_COMPAT
   128                  fops->compat_ioctl = mod_generic_compat_ioctl;
   129  #endif
   130          }

My investigation (as my abilities allowed) showed that problem rises in hardened kernel, because it adds some attribute named do_const to structure file_operations. Which seems is plugin to gcc, which makes it const by default.
Is this a bug or feature. And if second, then how can I workaround it?