linux-kernel - [PATCH tip/core/rcu 1/2] rcu: Make bugginess of code sample more evident

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Message-Id: <1363640108-15508-1-git-send-email-paulmck@linux.vnet.ibm.com>
Date:	Mon, 18 Mar 2013 13:55:07 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
	josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
	peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
	dhowells@...hat.com, edumazet@...gle.com, darren@...art.com,
	fweisbec@...il.com, sbw@....edu,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 1/2] rcu: Make bugginess of code sample more evident

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

One of the code samples in whatisRCU.txt shows a bug, but someone scanning
the document quickly might mistake it for a valid use of RCU.  Add some
screaming comments to help keep speed-readers on track.

Reported-by: Nathan Zimmer <nzimmer@....com>
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 Documentation/RCU/whatisRCU.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 0cc7820..10df0b8 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -265,9 +265,9 @@ rcu_dereference()
 		rcu_read_lock();
 		p = rcu_dereference(head.next);
 		rcu_read_unlock();
-		x = p->address;
+		x = p->address;	/* BUG!!! */
 		rcu_read_lock();
-		y = p->data;
+		y = p->data;	/* BUG!!! */
 		rcu_read_unlock();
 
 	Holding a reference from one RCU read-side critical section
-- 
1.8.1.5

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