linux-kernel - [PATCH tip/core/rcu 11/20] doc: rcu: Add more rationale for using rcu_read_lock

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Date:   Sun, 11 Nov 2018 11:56:36 -0800
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E . McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 11/20] doc: rcu: Add more rationale for using rcu_read_lock_sched in checklist

From: "Joel Fernandes (Google)" <joel@...lfernandes.org>

This commit explains why rcu_read_lock_sched is better than using
preempt_disable.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
---
 Documentation/RCU/checklist.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 49747717d905..8860ab2a897a 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -63,7 +63,7 @@ over a rather long period of time, but improvements are always welcome!
 	pointer must be covered by rcu_read_lock(), rcu_read_lock_bh(),
 	rcu_read_lock_sched(), or by the appropriate update-side lock.
 	Disabling of preemption can serve as rcu_read_lock_sched(), but
-	is less readable.
+	is less readable and prevents lockdep from detecting locking issues.
 
 	Letting RCU-protected pointers "leak" out of an RCU read-side
 	critical section is every bid as bad as letting them leak out
-- 
2.17.1