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    SubjectRe: [patch-2.3.40-pre6] kzalloc() (ala kmem_zalloc() of SVR4)
    On Fri, 21 Jan 2000, Jens Axboe wrote:

    > On Fri, Jan 21 2000, Jes Sorensen wrote:
    > > Tigran> Hi Linus, a common code sequence of calling kmalloc() and then
    > > Tigran> memset(p,0,size) can be optimized into a single exported
    > >
    > > The only thing it does is to introduce a new non standard name which
    > > makes current code less readable.
    >
    > I tend to agree. When (if) the concept of zeroing pages during idle
    > time ever gets into the kernel, then it might be worth it having
    > a way to get kmalloc() to return zeroed memory. For now it simply
    > reduces readability for zero gain.

    Consider this:

    get_free_page() returns a zeroed page. __get_free_page() returns a page.
    Both names are readable. What is the benefit of doing

    page = get_free_page(GFP_KERNEL);
    if (!page)
    /* failed */
    .. use page ..
    free_page(page);

    rather than:

    page = __get_free_page(GFP_KERNEL);
    if (!page)
    /* failed */
    clear_page((void *)page);
    ... use page ...
    free_page(page);

    You do agree that the first form is more readable although it wastes an
    extra if() (one is done inside get_free_page()), don't you? Therefore, for
    the same reason it is more readable to use kzalloc() in cases where you
    would do kmalloc()/memset(). What is the difference? (other than the fact
    that I made it a function instead of a macro or inline as Ingo correctly
    pointed out).

    Regards,
    Tigran.


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