On Mon, 2012-11-19 at 14:16 +0800, Li Zhong wrote:
> This patch tries to disable preemption for using smp_processor_id() in
> arch_spin_unlock_wait(),
> to avoid following report:
.../...
> diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
> index bb7cfec..7a7c31b 100644
> --- a/arch/powerpc/lib/locks.c
> +++ b/arch/powerpc/lib/locks.c
> @@ -72,8 +72,10 @@ void arch_spin_unlock_wait(arch_spinlock_t *lock)
> {
> while (lock->slock) {
> HMT_low();
> + preempt_disable();
> if (SHARED_PROCESSOR)
> __spin_yield(lock);
> + preempt_enable();
> }
I assume what you are protecting is the PACA access in SHARED_PROCESSOR
or is there more ?
In that case I'd say just make it use local_paca-> directly or something
like that. It doesn't matter if the access is racy, all processors will
have the same value for that field as far as I can tell.
Cheers,
Ben.
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