Messages in this thread | | | From | Doug Anderson <> | Date | Thu, 8 Feb 2024 08:03:50 -0800 | Subject | Re: [PATCHv6 2/2] watchdog/softlockup: report the most frequent interrupts |
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Hi,
On Thu, Feb 8, 2024 at 4:54 AM Bitao Hu <yaoma@linux.alibaba.com> wrote: > > +static void start_counting_irqs(void) > +{ > + int i; > + int local_nr_irqs; > + struct irq_desc *desc; > + u32 *counts = __this_cpu_read(hardirq_counts); > + > + if (!counts) { > + /* > + * nr_irqs has the potential to grow at runtime. We should read > + * it and store locally to avoid array out-of-bounds access. > + */ > + local_nr_irqs = READ_ONCE(nr_irqs);
nit: I don't think the READ_ONCE() is actually needed above. All that matters is that you're consistently using the same local variable ("local_nr_irqs") for allocating the array, looping, and then storing. No matter what optimizations might be happening and what else might be happening on other CPUs, once you put it in a local variable the compiler _must_ keep it consistent.
That being said, I don't think it really matters, so I'm not sure it's worth spinning your series just for that.
In any case, this patch looks good to me now. Thanks!
Reviewed-by: Douglas Anderson <dianders@chromium.org>
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