Messages in this thread Patch in this message |  | | Subject | Re: [PATCH 5/5] sched/deadline: Use return value of SCHED_WARN_ON() in bw accounting | From | Dietmar Eggemann <> | Date | Mon, 29 Jul 2019 17:59:04 +0100 |
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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; })
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