a couple more oddities(?) in mm code

a couple more oddities(?) in mm code

[Robert P. J. Day]

  (aside:  i am not trying to be an annoying pedant, i am merely
succeeding.  seriously, i'm currently working my way thru the MM code,
in a (possibly vain) attempt to finally understand it, and i
occasionally run across things that just look a bit, well, odd.  but
maybe it's just me.  let me know if any of this is inappropriate.)

  from filemap.c:

        if (!isblk) {
                /* FIXME: this is for backwards compatibility with 2.4 */

is there any compelling reason why any MM code still wants to be 2.4
backwards compatible?  aren't we past that point by now?

  also, from mmu_notifier.c, i find this *really* weird:

=============

int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
{
        return do_mmu_notifier_register(mn, mm, 1);
}
EXPORT_SYMBOL_GPL(mmu_notifier_register);

/*
 * Same as mmu_notifier_register but here the caller must hold the
 * mmap_sem in write mode.
 */
int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
{
        return do_mmu_notifier_register(mn, mm, 0);
}
EXPORT_SYMBOL_GPL(__mmu_notifier_register);

=============

  as a general rule, i normally expect the difference between two
kernel routines, say, func() and __func(), to be that func() would be
the generally callable one, while __func() would be a lower-level one,
perhaps using func() as a more convenient wrapper.  but the above
shows that those two routines represent *different* invocations of
do_mmu_notifier_register().  that's just not a pattern i'm used to
seeing.  doesn't it kind of fly in the face of kernel coding
standards?

rday
--

========================================================================
Robert P. J. Day                               Waterloo, Ontario, CANADA

            Linux Consulting, Training and Kernel Pedantry.

Web page:                                          http://crashcourse.ca
Twitter:                                       http://twitter.com/rpjday
========================================================================

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