From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Peter Zijlstra <peterz@infradead.org>,
luca abeni <luca.abeni@santannapisa.it>
Cc: Ingo Molnar <mingo@kernel.org>,
Juri Lelli <juri.lelli@redhat.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <Valentin.Schneider@arm.com>,
Qais Yousef <Qais.Yousef@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] sched/deadline: Use return value of SCHED_WARN_ON() in bw accounting
Date: Mon, 29 Jul 2019 17:59:04 +0100 [thread overview]
Message-ID: <a12e2330-50d4-b31f-14b5-5b386252d418@arm.com> (raw)
In-Reply-To: <20190729165434.GO31398@hirez.programming.kicks-ass.net>
On 7/29/19 5:54 PM, Peter Zijlstra wrote:
> On Fri, Jul 26, 2019 at 12:18:19PM +0200, luca abeni wrote:
>> Hi Dietmar,
>>
>> On Fri, 26 Jul 2019 09:27:56 +0100
>> Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>>
>>> To make the decision whether to set rq or running bw to 0 in underflow
>>> case use the return value of SCHED_WARN_ON() rather than an extra if
>>> condition.
>>
>> I think I tried this at some point, but if I remember well this
>> solution does not work correctly when SCHED_DEBUG is not enabled.
>
> Well, it 'works' in so far that it compiles. But it might not be what
> one expects. That is, for !SCHED_DEBUG the return value is an
> unconditional false.
>
> In this case I think that's fine, the WARN _should_ not be happending.
But there is commit 6d3aed3d ("sched/debug: Fix SCHED_WARN_ON() to
return a value on !CONFIG_SCHED_DEBUG as well")?
But it doesn't work with !CONFIG_SCHED_DEBUG
What compiles and work is (at least on Arm64).
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4012f98b9d26..494a767a4091 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -78,7 +78,7 @@
#ifdef CONFIG_SCHED_DEBUG
# define SCHED_WARN_ON(x) WARN_ONCE(x, #x)
#else
-# define SCHED_WARN_ON(x) ({ (void)(x), 0; })
+# define SCHED_WARN_ON(x) ({ (void)(x), x; })
next prev parent reply other threads:[~2019-07-29 16:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-26 8:27 [PATCH 0/5] sched/deadline: Fix double accounting in push_dl_task() & some cleanups Dietmar Eggemann
2019-07-26 8:27 ` [PATCH 1/5] sched/deadline: Fix double accounting of rq/running bw in push_dl_task() Dietmar Eggemann
2019-07-26 10:11 ` luca abeni
2019-07-29 8:59 ` Dietmar Eggemann
2019-07-29 16:10 ` Peter Zijlstra
2019-07-26 13:30 ` luca abeni
2019-07-29 9:00 ` Dietmar Eggemann
2019-07-31 10:32 ` Dietmar Eggemann
2019-07-26 8:27 ` [PATCH 2/5] sched/deadline: Remove unused int flags from __dequeue_task_dl() Dietmar Eggemann
2019-07-29 16:35 ` Peter Zijlstra
2019-07-29 17:12 ` Dietmar Eggemann
2019-07-26 8:27 ` [PATCH 3/5] sched/deadline: Use __sub_running_bw() throughout dl_change_utilization() Dietmar Eggemann
2019-07-29 16:47 ` Peter Zijlstra
2019-07-29 17:21 ` Dietmar Eggemann
2019-07-26 8:27 ` [PATCH 4/5] sched/deadline: Cleanup on_dl_rq() handling Dietmar Eggemann
2019-07-26 8:37 ` Valentin Schneider
2019-07-26 8:58 ` Qais Yousef
2019-07-26 9:20 ` Juri Lelli
2019-07-26 9:32 ` Valentin Schneider
2019-07-29 16:49 ` Peter Zijlstra
2019-07-30 6:41 ` Juri Lelli
2019-07-30 8:21 ` Peter Zijlstra
2019-07-31 17:32 ` Dietmar Eggemann
2019-07-31 20:20 ` luca abeni
2019-08-01 16:01 ` Dietmar Eggemann
2019-07-26 8:27 ` [PATCH 5/5] sched/deadline: Use return value of SCHED_WARN_ON() in bw accounting Dietmar Eggemann
2019-07-26 10:18 ` luca abeni
2019-07-29 16:54 ` Peter Zijlstra
2019-07-29 16:59 ` Dietmar Eggemann [this message]
2019-07-30 8:23 ` Peter Zijlstra
2019-07-30 16:08 ` Dietmar Eggemann
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