Re: linux-next: manual merge of the percpu tree with the tip tree

From: Frederic Weisbecker
Date: Thu Oct 09 2014 - 09:13:52 EST


On Thu, Oct 09, 2014 at 03:50:18PM +1100, Stephen Rothwell wrote:
> Hi all,
>
> Today's linux-next merge of the percpu tree got a conflict in
> kernel/irq_work.c between commit 76a33061b932 ("irq_work: Force raised
> irq work to run on irq work interrupt") from the tip tree and commit
> 22127e93c587 ("time: Replace __get_cpu_var uses") from the percpu tree.
>
> I fixed it up (see below) and can carry the fix as necessary (no action
> is required).
>
> --
> Cheers,
> Stephen Rothwell sfr@xxxxxxxxxxxxxxxx
>
> diff --cc kernel/irq_work.c
> index 385b85aded19,345d19edcdae..000000000000
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@@ -113,12 -113,10 +113,12 @@@ bool irq_work_needs_cpu(void
> {
> struct llist_head *raised, *lazy;
>
> - raised = &__get_cpu_var(raised_list);
> - lazy = &__get_cpu_var(lazy_list);
> + raised = this_cpu_ptr(&raised_list);
> + lazy = this_cpu_ptr(&lazy_list);

Ah thanks! The conflict is compile time rather than merge time, thanks
for spotting it!

Should we notify Linus about it? That's certainly something that should
be applied with the percpu tree.

> - if (llist_empty(raised) && llist_empty(lazy))
> - return false;
> +
> + if (llist_empty(raised) || arch_irq_work_has_interrupt())
> + if (llist_empty(lazy))
> + return false;
>
> /* All work should have been flushed before going offline */
> WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));


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