> > > 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! I don't think that works: the old code also relied on the fact that there could be only one cpu sending an smp_call_* IPI (serialized by call_lock). The current etr code exploits that to serialize all cpus: Do smp_call_function() to force all other cpus into clock_sync_cpu_start() where they sort of busy wait(!). Then the master cpu is syncing the clock and when it finished the other cpus may continue again and finally leave the smp_call_function interrupt handler. Your patch series however doesn't make sure anymore that there is only one cpu doing an smp_call_function*, so we may deadlock as soon as two cpus are trying to synchronize all cpus this way. After all I think the etr code should be converted to use stop_machine_run instead. However that doesn't allow for master/slave cpus. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
