On Sat, 24 Jan 2015, Dmitry Eremin-Solenikov wrote:
> 2015-01-24 20:48 GMT+03:00 Thomas Gleixner <[email protected]>:
> > On Thu, 15 Jan 2015, Dmitry Eremin-Solenikov wrote:
> >> static void sa1100_mask_irq(struct irq_data *d)
> >> {
> >> - ICMR &= ~BIT(d->hwirq);
> >> + u32 reg;
> >> + unsigned long flags;
> >> +
> >> + raw_spin_lock_irqsave(&lock, flags);
> >
> > What's the exact point of that lock? And how is it related to the
> > $subject of the patch?
>
> It is needed to protect ICMR register during RMW cycle, isn't it?
The original code has no protection for the RMW either.
And there is a simple reason for this. These functions are guaranteed
to be called with interrupts disabled and this is a uniprocessor
machine and it will never grow SMP support. So interrupts disabled is
serialization enough.
Thanks,
tglx
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