Messages in this thread | | | Date | Sat, 16 Jun 2012 09:32:19 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [RFC PATCH 09/10] POWERPC: smp: remove call to ipi_call_lock()/ipi_call_unlock() |
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On Tue, May 29, 2012 at 03:16:04PM +0800, Yong Zhang wrote: > From: Yong Zhang <yong.zhang@windriver.com> > > 1) call_function.lock used in smp_call_function_many() is just to protect > call_function.queue and &data->refs, cpu_online_mask is outside of the > lock. And it's not necessary to protect cpu_online_mask, > because data->cpumask is pre-calculate and even if a cpu is brougt up > when calling arch_send_call_function_ipi_mask(), it's harmless because > validation test in generic_smp_call_function_interrupt() will take care > of it. > > 2) For cpu down issue, stop_machine() will guarantee that no concurrent > smp_call_fuction() is processing.
However, there is an effort to get rid of stop_machine() from the CPU-down path... So something else will be needed.
Thanx, Paul
> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Paul Mackerras <paulus@samba.org> > Cc: linuxppc-dev@lists.ozlabs.org > --- > arch/powerpc/kernel/smp.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > index e4cb343..e1417c4 100644 > --- a/arch/powerpc/kernel/smp.c > +++ b/arch/powerpc/kernel/smp.c > @@ -571,7 +571,6 @@ void __devinit start_secondary(void *unused) > if (system_state == SYSTEM_RUNNING) > vdso_data->processorCount++; > #endif > - ipi_call_lock(); > notify_cpu_starting(cpu); > set_cpu_online(cpu, true); > /* Update sibling maps */ > @@ -601,7 +600,6 @@ void __devinit start_secondary(void *unused) > of_node_put(np); > } > of_node_put(l2_cache); > - ipi_call_unlock(); > > local_irq_enable(); > > -- > 1.7.5.4 >
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