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Date:   Thu, 7 Nov 2019 14:11:46 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Patrick Bellasi <patrick.bellasi@matbug.net>
Cc:     Qais Yousef <qais.yousef@arm.com>, Ingo Molnar <mingo@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched: core: fix compilation error when cgroup not
 selected
Message-ID: <20191107131146.GJ4131@hirez.programming.kicks-ass.net>
References: <20191105112212.596-1-qais.yousef@arm.com>
 <20191107072525.GA19642@darkstar>
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On Thu, Nov 07, 2019 at 07:25:25AM +0000, Patrick Bellasi wrote:
> [ +Randy ]
> 
> Hi Qais,
> 
> On 05-Nov 11:22, Qais Yousef wrote:
> > When cgroup is disabled the following compilation error was hit
> > 
> > 	kernel/sched/core.c: In function ‘uclamp_update_active_tasks’:
> > 	kernel/sched/core.c:1081:23: error: storage size of ‘it’ isn’t known
> > 	  struct css_task_iter it;
> > 			       ^~
> > 	kernel/sched/core.c:1084:2: error: implicit declaration of function ‘css_task_iter_start’; did you mean ‘__sg_page_iter_start’? [-Werror=implicit-function-declaration]
> > 	  css_task_iter_start(css, 0, &it);
> > 	  ^~~~~~~~~~~~~~~~~~~
> > 	  __sg_page_iter_start
> > 	kernel/sched/core.c:1085:14: error: implicit declaration of function ‘css_task_iter_next’; did you mean ‘__sg_page_iter_next’? [-Werror=implicit-function-declaration]
> > 	  while ((p = css_task_iter_next(&it))) {
> > 		      ^~~~~~~~~~~~~~~~~~
> > 		      __sg_page_iter_next
> > 	kernel/sched/core.c:1091:2: error: implicit declaration of function ‘css_task_iter_end’; did you mean ‘get_task_cred’? [-Werror=implicit-function-declaration]
> > 	  css_task_iter_end(&it);
> > 	  ^~~~~~~~~~~~~~~~~
> > 	  get_task_cred
> > 	kernel/sched/core.c:1081:23: warning: unused variable ‘it’ [-Wunused-variable]
> > 	  struct css_task_iter it;
> > 			       ^~
> > 	cc1: some warnings being treated as errors
> > 	make[2]: *** [kernel/sched/core.o] Error 1
> > 
> > Fix by protetion uclamp_update_active_tasks() with
> > CONFIG_UCLAMP_TASK_GROUP
> > 
> > Fixes: babbe170e053 ("sched/uclamp: Update CPU's refcount on TG's clamp changes")
> > Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> 
> Thanks for posting this again.
> 
> We now have three "versions" of this same fix, including:
>  - the original bug report by Randy and a fix from me here:
>    Message-ID: <8736gv2gbv.fsf@arm.com>
>    https://lore.kernel.org/linux-next/8736gv2gbv.fsf@arm.com/
>  - and a follow up patch from Arnd:
>    Message-ID: <20190918195957.2220297-1-arnd@arndb.de>
>    https://lore.kernel.org/lkml/20190918195957.2220297-1-arnd@arndb.de/
> 
> So, I guess now we just have to pick the one with the changelog we
> prefer. :)
> 
> In all cases we should probably add:
> 
>   Reported-by: Randy Dunlap <rdunlap@infradead.org>
>   Tested-by: Randy Dunlap <rdunlap@infradead.org>

Argh, ok, I missed them all too. Picked up this one for sched/urgent and
added the above.

Thanks!