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    SubjectRe: random.c changes for sparse irq_desc are crap

    * Matt Mackall <mpm@selenic.com> wrote:

    > On Wed, 2008-12-31 at 16:14 -0800, Yinghai Lu wrote:
    > > On Wed, Dec 31, 2008 at 3:40 PM, Matt Mackall <mpm@selenic.com> wrote:
    > > > On Wed, 2008-12-31 at 15:07 -0800, Yinghai Lu wrote:
    > > >> Matt Mackall wrote:
    > > >> > I just noticed you merged a change that pointlessly converts two
    > > >> > random.c functions into ugly random.h inlines without going through the
    > > >> > maintainer.
    > > >> >
    > > >> > I also don't like the look of the newly-introduced sparse variants of
    > > >> > these functions. Failure to find an irq descriptor in
    > > >> > get_timer_rand_state is a BUG_ON should-never-happen sort of condition,
    > > >> > not something to silently ignore. Letting the code try to dereference
    > > >> > NULL is preferred here: we'll actually be able to find and fix the
    > > >> > broken driver that's throwing around meaningless irq vectors.
    > > >> >
    > > >> > Throwing away the timer_state pointer in the set_timer_rand_state
    > > >> > function is similarly bogus in addition to being a memory leak.
    > > >> >
    > > >> > Please fix this up.
    > > >> >
    > > >>
    > > >> want something like this?
    > > >
    > > > Not quite.
    > > >
    > > > First, please turn these back into normal functions in random.c.
    > > > Inlining functions is generally discouraged these days unless you have a
    > > > good reason and numbers to back it up.
    > >
    > > Ingo wanted to hide that #ifdef to .h
    >
    > Ahh. I think that makes sense in some situations, but I'd prefer not to
    > do that here. Some headers are actually meant to be more readable than
    > the corresponding .c file. Also, we still end up with an ifdef in the .c
    > file so we're not actually winning.

    Yinghai - i think Matt is right and there are a number of things we could
    do to improve cleanliness here. (Matt, sorry about this - we'll quickly
    fix it.)

    The most important thing to observe is that the irq_desc->timer_rand_state
    cleanup you did should be made unconditional, and should not depend on
    SPARSE_IRQ. That will eliminate most of the #ifdefs, and it makes the
    random.c and random.h impact rather straightforward.

    Another cleanliness detail is that these types of checks:

    #ifndef CONFIG_SPARSE_IRQ
    if (irq >= nr_irqs)
    return;
    #endif
    can go away completely. They were needed from the sparseirq data model
    that had a dynamic array size - but that is not so anymore, so we can
    remove these complications.

    Agreed?

    Ingo


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