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    SubjectRe: [KEXEC][2.5.69] Re: Updated kexec diffs...
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    Andrew Morton <akpm@digeo.com> writes:

    > ebiederm@xmission.com (Eric W. Biederman) wrote:
    > >
    > > And Andrew has it in 2.5.69-mm4 and is busy pestering me about compile
    > > errors.
    >
    > I'm like that.

    And I appreciate it. This was mostly an observation there was
    something reminding me to get back and fix the issue.

    > I've dropped out a lot of the NORET stuff. It generates warnings on all
    > other architectures, because their machine_restart, machine_halt and
    > machine_power_off definitions don't have necessary attributes and don't
    > have the while(1); at the end.

    Yes there is a big const correctness type problem here.

    First for machine_restart it is 100% correct. And at least sys_reboot
    assumes that machine_restart will not return, even before my patch.

    And I don't know of a case where it makes sense for machine_halt and
    machine_power_off to return. Hence I deliberately made those cases
    the same. Especially as every real implementation I traced does not
    return. It is only the stupid cases like on x86 where we don't do
    anything that these routines actually return.

    In the context of my patch stop_this_cpu needs to be marked noreturn.
    As long as the fundamental routines get marked I don't expect to see
    a lot of routines getting a while(1); I admit stop_apics also
    needs a while(1); but only because gcc cannot trace it.

    And since this also generates warnings on other architectures
    it looks like someone (me) needs to go through the various
    architectures and add a bunch of noreturn attributes to
    the appropriate functions.

    The basic question is for documenting and enforcing the noreturn
    dependency. Is it more of a help or a hindrance to use gcc noreturn
    tag?

    And while I am pretty certain this is the correct thing to do I
    should break this out from the reboot_on_bsp patch. With the
    other architectures involved this is enough of a separate issue that a
    second set of patches is needed to maintain this cleanly.

    Eric
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