sched: avoid using ilog2() in sched.h

<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.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yury Norov <[email protected]>
Cc: Amit Daniel Kachhap <[email protected]>
Cc: Anna-Maria Behnsen <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Rasmus Villemoes <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ulf Hansson <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: Yury Norov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 1 insertions, 1 deletions

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];
 }