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Message-Id: <20231006102518.2452758-4-mingo@kernel.org>
Date: Fri, 6 Oct 2023 12:25:18 +0200
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
Daniel Bristot de Oliveira <bristot@...hat.com>,
Valentin Schneider <vschneid@...hat.com>,
Frederic Weisbecker <frederic@...nel.org>,
Joel Fernandes <joel@...lfernandes.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 3/3] sched/nohz: Remove weird error handling from find_new_ilb()
find_new_ilb() returns nr_cpu_ids on failure - which is a weird
choice in itself: not only is it a global variable, it is
a +1 out of bounds CPU index...
Its only user, kick_ilb(), then checks the return against nr_cpu_ids
to decide to return.
Instead of this, use a standard -1 return on failure to find an
idle CPU, as the argument is signed already.
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org
---
kernel/sched/fair.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d4e90d15bd77..dad60576cf56 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11572,7 +11572,7 @@ static inline int find_new_ilb(void)
return ilb_cpu;
}
- return nr_cpu_ids;
+ return -1;
}
/*
@@ -11593,8 +11593,7 @@ static void kick_ilb(unsigned int flags)
nohz.next_balance = jiffies+1;
ilb_cpu = find_new_ilb();
-
- if (ilb_cpu >= nr_cpu_ids)
+ if (ilb_cpu < 0)
return;
/*
--
2.39.2
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