lkml.org 
[lkml]   [1998]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: 2.1.118 Tons of oopes
    Date
    In article <19980831082313.26439.qmail@hog.ctrl-c.liu.se>,
    <wingel@t1.ctrl-c.liu.se> wrote:
    >tantalophile.demon.co.uk wrote:
    >>Richard Gooch wrote:
    >>> Yes, I can see the benefit of avoiding the NULL check. It would be
    >>> nice to be able to do this. However, that would then require every
    >>> driver to be updated on every addition of a new VFS method.
    >>
    >>It's possible, in the NULL case, that the check is faster than the
    >>function call to the default function.
    >
    >Which is a rather bogus argument, trying to call a VFS method which
    >is NULL usually indicates an error and isn't time critical.

    No, some functions are NULL quite normally, simply because it's
    something that the low-level driver or FS doesn't want to bother with.

    For example, networked filesystems often need more hooks to tell the
    system that "ok, something changed", while a local filesystem doesn't
    need that and can just let the VFS layer do whatever it wants to do
    without having to worry about anybody else doing something over the
    network.

    As such, NULL pointers can often be the _default_ rather than being a
    sign of error cases. And the NULL case may be the fast and
    timing-sensitive one. This is true of the dcache hashing stuff, for
    example, where there are special (and slow) routines for certain
    filesystems that want to do stupid name mangling.

    Linus

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html

    \
     
     \ /
      Last update: 2005-03-22 13:44    [W:0.044 / U:0.260 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site