Messages in this thread | | | Subject | Re: [PATCH v5 1/8] smp: Introduce a generic on_each_cpu_mask function | Date | Thu, 05 Jan 2012 14:17:54 +0100 | From | "Michal Nazarewicz" <> |
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On Tue, 03 Jan 2012 23:26:24 +0100, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Mon, 2 Jan 2012 12:24:12 +0200 > Gilad Ben-Yossef <gilad@benyossef.com> wrote: > >> on_each_cpu_mask calls a function on processors specified my cpumask, >> which may include the local processor.
>> @@ -132,6 +139,15 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info) >> local_irq_enable(); \ >> 0; \ >> }) >> +#define on_each_cpu_mask(mask, func, info, wait) \ >> + do { \ >> + if (cpumask_test_cpu(0, (mask))) { \ >> + local_irq_disable(); \ >> + (func)(info); \ >> + local_irq_enable(); \ >> + } \ >> + } while (0) > > Why is the cpumask_test_cpu() call there? It's hard to think of a > reason why "mask" would specify any CPU other than "0" in a > uniprocessor kernel.
It may specify none. For instance, in drain_all_pages() case, if the CPU has no pages on PCP lists, the mask will be empty and so the cpumask_test_cpu() will return zero.
-- Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał “mina86” Nazarewicz (o o) ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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