On 05/29/2012 01:57 PM, Yong Zhang wrote:
> On Tue, May 29, 2012 at 01:31:54PM +0530, Srivatsa S. Bhat wrote:
>> This looks odd. IRQs must not have been enabled at this point.
>> Just remove the call to local_irq_enable() that is found a few lines above
>> this line and then you won't have to add this call to local_irq_disable().
>
> Yeah, have thought about it. But because I was not sure there is
> special need to enalbe irq that early (don't know much about sparc),
> I decided to make minor change :)
>
> Since we have gotten confirmation from David, I'm sending out the
> new version. Please check it.
>
> Thanks,
> Yong
>
> ---
> From: Yong Zhang <yong.zhang@xxxxxxxxxxxxx>
> Date: Tue, 29 May 2012 12:56:08 +0800
> Subject: [UPDATED] [RFC PATCH 8/10] SPARC: smp: remove call to
> ipi_call_lock_irq()/ipi_call_unlock_irq()
>
> 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.
>
> And also delay irq enable to after set_cpu_online().
>
> Signed-off-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: sparclinux@xxxxxxxxxxxxxxx
> ---
Looks good.
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
> arch/sparc/kernel/smp_64.c | 7 +------
> 1 files changed, 1 insertions(+), 6 deletions(-)
>
> diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
> index f591598..781bcb1 100644
> --- a/arch/sparc/kernel/smp_64.c
> +++ b/arch/sparc/kernel/smp_64.c
> @@ -103,8 +103,6 @@ void __cpuinit smp_callin(void)
> if (cheetah_pcache_forced_on)
> cheetah_enable_pcache();
>
> - local_irq_enable();
> -
> callin_flag = 1;
> __asm__ __volatile__("membar #Sync\n\t"
> "flush %%g6" : : : "memory");
> @@ -124,9 +122,8 @@ void __cpuinit smp_callin(void)
> while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
> rmb();
>
> - ipi_call_lock_irq();
> set_cpu_online(cpuid, true);
> - ipi_call_unlock_irq();
> + local_irq_enable();
>
> /* idle thread is expected to have preempt disabled */
> preempt_disable();
> @@ -1308,9 +1305,7 @@ int __cpu_disable(void)
> mdelay(1);
> local_irq_disable();
>
> - ipi_call_lock();
> set_cpu_online(cpu, false);
> - ipi_call_unlock();
>
> cpu_map_rebuild();
>
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