Re: linux-next: build failure after merge of the tip tree

From: Len Brown
Date: Sun Jan 19 2014 - 20:00:27 EST

On Wed, Jan 15, 2014 at 10:58 PM, Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> Hi all,
> After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
> failed like this:
> arch/x86/kernel/process.c: In function 'mwait_idle':
> /scratch/sfr/next/arch/x86/kernel/process.c:434:3: error: implicit declaration of function '__monitor' [-Werror=implicit-function-declaration]
> __monitor((void *)&current_thread_info()->flags, 0, 0);
> ^
> arch/x86/kernel/process.c:437:4: error: implicit declaration of function '__sti_mwait' [-Werror=implicit-function-declaration]
> __sti_mwait(0, 0);
> ^
> Caused by commit 16824255394f ("x86, acpi, idle: Restructure the mwait
> idle routines") interacting with commit 7760518cce95 ("x86 idle: restore
> mwait_idle()") from the idle tree.
> I am not sure how to fix this so I just reverted the idle tree commit for
> now (since it reverted cleanly). Please let me know if there is a better
> solution.

IMO, a regression fix (restore mwait_idle()) is more important than a clean up
(restructure mwait routines), and the clean-up should take a back seat;
in -tip, in -next, upstream, and in -stable.

Also, I'm wondering if that clean-up went too far -- as not all users of mwait
are necessarily under the same conditions...

Len Brown, Intel Open Source Technology Center
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