On Sun, 2009-08-23 at 22:40 -0700, Nick Piggin wrote: > On Fri, Aug 21, 2009 at 11:51:50PM +0000, Suresh B wrote: > > Commit-ID: 269c861baa2fe7c114c3bc7831292758d29eb336 > > Gitweb: http://git.kernel.org/tip/269c861baa2fe7c114c3bc7831292758d29eb336 > > Author: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> > > AuthorDate: Wed, 19 Aug 2009 18:05:35 -0700 > > Committer: H. Peter Anvin <hpa@xxxxxxxxx> > > CommitDate: Fri, 21 Aug 2009 16:25:43 -0700 > > > > generic-ipi: Allow cpus not yet online to call smp_call_function with irqs disabled > > > > Because of deadlock possiblities smp_call_function() is not allowed to > > be called with interrupts disabled. Add an exception for the cpu not > > yet online, as no one else can send smp call function interrupt to this > > cpu that is not yet online and as such deadlock condition is not possible. > > > > Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx> > > Acked-by: Nick Piggin <npiggin@xxxxxxx> > > Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx> > > I don't know if we should allow the use of smp_call_function here -- > only call_function_single. CPU hotplug code is required to set up > some call_function data and if the cpu is offline then it might not > be set up correctly. We are doing the required allocations in CPU_UP_PREPARE. So we should be okay for any smp_call_function usage. > Also, I would say that we should just restrict this to wait==1 case > because in that case the stack can trivially be used for data. In > the wait==0 case, it is more complex. In the current implementation > it should be OK (it uses per-cpu data), but we've used kmalloc > there in the past, which probably wouldn't work either. In future if we add any kmalloc, we already have checks in kmalloc() that can be easily caught. I would like to make this change as generic as possible. thanks, suresh -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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