[PATCH] arm64: mm: remove the redundant code

[Huang Shijie]

On Mon, Apr 18, 2016 at 02:08:20PM +0100, Catalin Marinas wrote:
> > @@ -212,10 +212,6 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
> >     tsk = current;
> >     mm  = tsk->mm;
> >
> > -   /* Enable interrupts if they were enabled in the parent context. */
> > -   if (interrupts_enabled(regs))
> > -           local_irq_enable();
>
> We indeed don't have to re-enable interrupts here as they have been
> enabled by the calling code in entry.S. But have you run this with
> CONFIG_TRACE_IRQFLAGS enabled? I don't think there is any issue, just a
> sanity check.
I tested this patch with the CONFIG_TRACE_IRQFLAGS/CONFIG_PROVE_LOCKING/CONFIG_DEBUG_LOCKDEP
enabled, in my Juno board, it works fine.

Also I find that with this patch, if we want to check the lockdep stat with:
    #cat /proc/lockdep_stats

The "redundant hardirq ons" become 0. Without this patch, the redundant
hardirq ons" is a big number, such as 123444.

thanks
Huang Shijie
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.