linux-kernel - Re: [PATCH v8 4/8] smp: add func to IPI cpus based on parameter func

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Date:	Thu, 9 Feb 2012 10:08:16 +0200
From:	Gilad Ben-Yossef <gilad@...yossef.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Michal Nazarewicz <mina86@...a86.com>,
	linux-kernel@...r.kernel.org, Chris Metcalf <cmetcalf@...era.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Russell King <linux@....linux.org.uk>, linux-mm@...ck.org,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>,
	Sasha Levin <levinsasha928@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, Avi Kivity <avi@...hat.com>,
	Kosaki Motohiro <kosaki.motohiro@...il.com>,
	Milton Miller <miltonm@....com>
Subject: Re: [PATCH v8 4/8] smp: add func to IPI cpus based on parameter func

On Thu, Feb 9, 2012 at 2:03 AM, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Wed, 08 Feb 2012 10:30:51 +0100
> "Michal Nazarewicz" <mina86@...a86.com> wrote:
>
>> >     } while (0)
>> > +/*
>> > + * Preemption is disabled here to make sure the
>> > + * cond_func is called under the same condtions in UP
>> > + * and SMP.
>> > + */
>> > +#define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags) \
>> > +   do {                                            \
>>
>> How about:
>>
>>               void *__info = (info);
>>
>> as to avoid double execution.
>
> Yup.  How does this look?
>
>
> From: Andrew Morton <akpm@...ux-foundation.org>
> Subject: smp-add-func-to-ipi-cpus-based-on-parameter-func-update-fix
>
> - avoid double-evaluation of `info' (per Michal)
> - parenthesise evaluation of `cond_func'
>
> Cc: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
> Cc: Gilad Ben-Yossef <gilad@...yossef.com>
> Cc: Michal Nazarewicz <mina86@...a86.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
>
>  include/linux/smp.h |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> --- a/include/linux/smp.h~smp-add-func-to-ipi-cpus-based-on-parameter-func-update-fix
> +++ a/include/linux/smp.h
> @@ -168,10 +168,11 @@ static inline int up_smp_call_function(s
>  */
>  #define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags)\
>        do {                                                    \
> +               void *__info = (info);                          \
>                preempt_disable();                              \
> -               if (cond_func(0, info)) {                       \
> +               if ((cond_func)(0, __info)) {                   \
>                        local_irq_disable();                    \
> -                       (func)(info);                           \
> +                       (func)(__info);                         \
>                        local_irq_enable();                     \
>                }                                               \
>                preempt_enable();                               \
> _
>

Right, I missed that. I hate macros.

As I was requested to correct some comments I'll send a re-spin.
I folded your patch into the original one (and kept the Signed-off-by,
I hope it's OK).

BTW -  I used a macro since I imitated the rest of the code in smp.h
but is there any
reason not to use an inline macro here?

Thanks!
Gilad

-- 
Gilad Ben-Yossef
Chief Coffee Drinker
gilad@...yossef.com
Israel Cell: +972-52-8260388
US Cell: +1-973-8260388
http://benyossef.com

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