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From: Yury Norov <yury.norov@gmail.com>
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Cc: Yury Norov <yury.norov@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Amit Daniel Kachhap <amit.kachhap@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
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	Daniel Lezcano <daniel.lezcano@linaro.org>,
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	Johannes Weiner <hannes@cmpxchg.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Kees Cook <keescook@chromium.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Tejun Heo <tj@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Zefan Li <lizefan.x@bytedance.com>
Subject: [PATCH 2/6] sched: avoid using ilog2() in sched.h
Date: Mon, 27 May 2024 17:56:44 -0700
Message-Id: <20240528005648.182376-3-yury.norov@gmail.com>
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<linux/sched.h> indirectly via cpumask.h path includes the ilog2.h header
to calculate ilog2(TASK_REPORT_MAX). The following patches drops sched.h
dependency on cpumask.h, and to have a successful build, the header has
to be included explicitly.

sched.h is a frequently included header, and it's better to keep the
dependency list as small as possible. So, instead of including ilog2.h
for a single BUILD_BUG_ON() check, the same check may be implemented by
taking exponent of the other part of equation.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/linux/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 61591ac6eab6..98abb07de149 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1604,7 +1604,7 @@ static inline char task_index_to_char(unsigned int state)
 {
 	static const char state_char[] = "RSDTtXZPI";
 
-	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != sizeof(state_char) - 1);
+	BUILD_BUG_ON(TASK_REPORT_MAX * 2 != 1 << (sizeof(state_char) - 1));
 
 	return state_char[state];
 }
-- 
2.40.1