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    SubjectRe: [PATCH 11/11] s390: convert to generic helpers for IPI function calls
    On Wed, Apr 23 2008, Jens Axboe wrote:
    > On Wed, Apr 23 2008, Heiko Carstens wrote:
    > > On Tue, Apr 22, 2008 at 08:50:27PM +0200, Jens Axboe wrote:
    > > > This converts s390 to use the new helpers for smp_call_function() and
    > > > friends, and adds support for smp_call_function_single(). Not tested,
    > > > but it compiles.
    > > >
    > > > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    > > > Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    > > > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
    > >
    > > Your generic patch changes semantics of smp_call_function(). At least the
    > > s390 version of smp_call_function() mask used to not return unless all IPIs
    > > where received on the target cpus.
    > > Your patch changes that. It will already return as soon as all IPIs have
    > > been sent. Unfortunately Martin's etr code in arch/s390/kernel/time.c
    >
    > Yep, this is what I mentioned in the intro mail.
    >
    > > relies on exactly the old semantics.
    >
    > OK, I could not see anything which relied on that and I did think that
    > it was a somewhat odd interface. By the time that smp_call_function()
    > stops waiting for startups, we could easily be in the condition that the
    > N-1 CPUs executed the function part a long time ago. I just didn't see
    > much usefulness in that, you may as well just set wait == 1 in that
    > case.
    >
    > > Since this seems to be an s390 only issue, could you just drop the s390
    > > conversion patch? We'll have to think about how to change the err code
    > > and convert later I guess.
    >
    > I'll drop the s390 bits. I can easily add something like
    > smp_call_function_foo() that has this behaviour.

    I added an smp_call_function_sync() for this purpose and kept the s390
    conversion, I would very much appreciate if you could look it over. I
    wont post the full patchset again today, but you can inspect it here:

    http://git.kernel.dk/?p=linux-2.6-block.git;a=shortlog;h=refs/heads/generic-ipi

    The interesting bits are patch #1 for the generic bits and patch #11 for
    the s390 part. Thanks!

    --
    Jens Axboe



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