linux-kernel - [tip: core/rcu] lockdep: Complain only once about RCU in extended quiescent state

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Date:   Fri, 31 Jul 2020 09:23:30 -0000
From:   "tip-bot2 for Paul E. McKenney" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: core/rcu] lockdep: Complain only once about RCU in extended
 quiescent state

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     d29e0b26b020422cc51b5b51733cc50fcf443965
Gitweb:        https://git.kernel.org/tip/d29e0b26b020422cc51b5b51733cc50fcf443965
Author:        Paul E. McKenney <paulmck@...nel.org>
AuthorDate:    Thu, 28 May 2020 08:49:29 -07:00
Committer:     Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Mon, 29 Jun 2020 11:58:51 -07:00

lockdep: Complain only once about RCU in extended quiescent state

Currently, lockdep_rcu_suspicious() complains twice about RCU read-side
critical sections being invoked from within extended quiescent states,
for example:

	RCU used illegally from idle CPU!
	rcu_scheduler_active = 2, debug_locks = 1
	RCU used illegally from extended quiescent state!

This commit therefore saves a couple lines of code and one line of
console-log output by eliminating the first of these two complaints.

Link: https://lore.kernel.org/lkml/87wo4wnpzb.fsf@nanos.tec.linutronix.de
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Will Deacon <will@...nel.org>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/locking/lockdep.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 29a8de4..0a7549d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5851,9 +5851,7 @@ void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
 	pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
 	       !rcu_lockdep_current_cpu_online()
 			? "RCU used illegally from offline CPU!\n"
-			: !rcu_is_watching()
-				? "RCU used illegally from idle CPU!\n"
-				: "",
+			: "",
 	       rcu_scheduler_active, debug_locks);
 
 	/*