linux-kernel - Re: [PATCH] Make smp_call_function{_single} go WARNING and return -EINVAL on !SMP (was Re: [PATCH] i386/x86_64: NMI watchdog: Protect smp_call_function() within CONFIG

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Message-ID: <a781481a0706070933ld67e06escaddf1b7be2b017@mail.gmail.com>
Date:	Thu, 7 Jun 2007 22:03:08 +0530
From:	"Satyam Sharma" <satyam.sharma@...il.com>
To:	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Cc:	"Ingo Molnar" <mingo@...hat.com>,
	"Andi Kleen" <andi@...stfloor.org>, "Alan Cox" <alan@...hat.com>,
	"Heiko Carstens" <heiko.carstens@...ibm.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"David Miller" <davem@...emloft.net>
Subject: Re: [PATCH] Make smp_call_function{_single} go WARNING and return -EINVAL on !SMP (was Re: [PATCH] i386/x86_64: NMI watchdog: Protect smp_call_function() within CONFIG_SMP)

> On 6/7/07, Satyam Sharma <satyam.sharma@...il.com> wrote:
> > [...]
> > BTW: smp_call_function() simply returns 0 and
> > smp_call_function_single() simply returns -EBUSY when !SMP.
> > These appear to be just some ad hoc values. IMHO, we should
> > be going BUG() in both these cases because "other" CPUs for
> > !SMP are undefined / meaningless.
>
> 79974a0e4c6be6e9a3717b4c5a5d5c44c36b1653 from a couple
> weeks back (discussed on http://lkml.org/lkml/2007/5/14/68 i.e.
> [patch] Let smp_call_function_single return -EBUSY.) introduced
> this behaviour. [ Adding Heiko Carstens, Andrew and David Miller
> to Cc: list. ]
>
> I realized a warning would be more appropriate for this case than
> a BUG at the last moment ... this doesn't quite meet Linus' "You
> killed my father; prepare to die!" criterion :-)

Ugh, Gmail murdered this patch:

>  static inline int smp_call_function_single(int cpuid, void (*func)
> (void *info),
>                                            void *info, int retry, int wait)

Resending as attachment.

View attachment "make-smp_call_function-go-warning-on-up.patch" of type "text/x-patch" (2287 bytes)