Messages in this thread | | | Date | Sat, 22 Jan 2011 12:13:07 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86: Don't copy per_cpu cpuinfo for BSP two times |
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On Fri, Jan 21, 2011 at 03:29:54PM -0800, Yinghai Lu wrote: > > smp_store_cpu_info(0) will do that. > > Signed-off-by: Yinghai Lu <yinghai@kernel.org> > > --- > arch/x86/kernel/smpboot.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > Index: linux-2.6/arch/x86/kernel/smpboot.c > =================================================================== > --- linux-2.6.orig/arch/x86/kernel/smpboot.c > +++ linux-2.6/arch/x86/kernel/smpboot.c > @@ -1071,13 +1071,13 @@ void __init native_smp_prepare_cpus(unsi > > preempt_disable(); > smp_cpu_index_default(); > - memcpy(__this_cpu_ptr(&cpu_info), &boot_cpu_data, sizeof(cpu_info)); > - cpumask_copy(cpu_callin_mask, cpumask_of(0)); > - mb(); > + > /* > * Setup boot CPU information > */ > smp_store_cpu_info(0); /* Final full version of the data */ > + cpumask_copy(cpu_callin_mask, cpumask_of(0)); > + mb();
Question: why do we need the memory barrier there? We're running on the BSP and long before smp_init() to be all careful about the callin_mask. It could be there as a left over from the 32 and 64-bit merge, AFAICT from git history...
Thanks.
-- Regards/Gruss, Boris.
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