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    SubjectRe: [PATCH] debugfs: Revamp debugfs_create_{u,x,s}{8,16,32,64} to support signed integers

    On Sun, 2007-12-16 at 09:05 -0800, Greg KH wrote:
    > On Sun, Dec 16, 2007 at 05:37:59PM +0100, Mattias Nissler wrote:
    > > This makes debugfs use its own file_operations for the value accessor files
    > > created by debugfs_create_XXX. Having that, we can also have proper versions
    > > for signed integers.
    > Why not tweak the "SIMPLE_ATTRIBUTE" code to support this instead? That
    > way debugfs and all other filesystems could also use these attributes?

    I expected that question ;-) Actually, I had a version that did this.
    But it ended up being ugly, cause SIMPLE_ATTRIBUTEs expect to access the
    values via get/set functions using u64. Here is what I did and why I
    didn't like it:

    * I made the set/get function interface more generic (as it is in the
    debugfs patch), i.e. getting passed the buf, so they have to
    decode/encode whatever they like into the buf instead of working with
    * This means either all code using SIMPLE_ATTRIBUTES must be changed, or
    I need to add another wrapper macro that produces suitable get/set
    functions from the u64 versions it gets passed.
    * Changing all SIMPLE_ATTRIBUTE users is not what I want, cause moving
    the csnprintf()/strtoull() calls out of the SIMPLE_ATTRIBUTE code means
    it becomes less simple to use it, right?
    * The wrapper is actually possible, but it suffers from cases where
    somebody passes NULL for a get or set function (which is actually
    expected, compare the code in libfs.c) It is possible to hack around
    this, but it's ugly.

    Then I thought, well, SIMPLE_ATTRIBUTEs are made to work with a set/get
    function pair. But debugfs expects a pointer to an actual variable
    anyway, so just bypass the SIMPLE_ATTRIBUTE code and make debugfs use
    it's own file_operations (most of them shamelessly stolen from the
    SIMPLE_ATTRIBUTE code, I admit).


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      Last update: 2007-12-16 18:23    [W:0.022 / U:9.012 seconds]
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