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    Subject[PATCH 08/10] SPARC: smp: remove call to ipi_call_lock_irq()/ipi_call_unlock_irq()
    Date
    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.

    Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: sparclinux@vger.kernel.org
    ---
    arch/sparc/kernel/smp_64.c | 6 ++----
    1 files changed, 2 insertions(+), 4 deletions(-)

    diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
    index f591598..60e745c 100644
    --- a/arch/sparc/kernel/smp_64.c
    +++ b/arch/sparc/kernel/smp_64.c
    @@ -124,9 +124,9 @@ void __cpuinit smp_callin(void)
    while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
    rmb();

    - ipi_call_lock_irq();
    + local_irq_disable();
    set_cpu_online(cpuid, true);
    - ipi_call_unlock_irq();
    + local_irq_enable();

    /* idle thread is expected to have preempt disabled */
    preempt_disable();
    @@ -1308,9 +1308,7 @@ int __cpu_disable(void)
    mdelay(1);
    local_irq_disable();

    - ipi_call_lock();
    set_cpu_online(cpu, false);
    - ipi_call_unlock();

    cpu_map_rebuild();

    --
    1.7.5.4


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