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    SubjectRe: linux-ipsec: valid module function pointer?
    On Fri, Sep 17, 1999 at 04:21:44PM -0400, Richard Guy Briggs wrote:
    > Can anyone suggest a way to test a module function pointer for
    > validity? The problem is that we currently save pointers to kernel
    > space funciton pointers which might go away if a pcmcia card is
    > removed. Is there a way to test if the function pointer belongs to a
    > module which is still loaded?

    No, you don't.

    Counter example: Something is unloaded, and after a while, something
    else is loaded into same memory area.

    Now how you know that the pointer is valid ?
    I would say: you don't.

    A way out could be eternally growing array of pointers, which may then
    latter be removoked by writing a NULL back into place at module unload.
    ... but it would be eternally growing non-swappable array... Not good.

    You must find some other approach. What is the original problem, which
    is now "solved" with cached function pointers ?

    > slainte mhath, RGB
    > - --
    > Richard Guy Briggs -- PGP key available Auto-Free Ottawa! Canada
    > <> </>
    > Prevent Internet Wiretapping! -- FreeS/WAN:<>

    /Matti Aarnio <>

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