From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 22 Sep 2010 06:38:44 +0000 (+0200)
Subject: rcu: rcu_read_lock_bh_held(): disabling irqs also disables bh
X-Git-Tag: firefly_0821_release~7613^2~3816^2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=b3a084b9b684622b149e8dcf03855bf0d5fb588b;p=firefly-linux-kernel-4.4.55.git

rcu: rcu_read_lock_bh_held(): disabling irqs also disables bh

rcu_dereference_bh() doesnt know yet about hard irq being disabled, so
lockdep can trigger in netpoll_rx() after commit f0f9deae9e7c4 (netpoll:
Disable IRQ around RCU dereference in netpoll_rx)

Reported-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9fbc54a2585d..83af1f8d8b74 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -454,7 +454,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  * Makes rcu_dereference_check() do the dirty work.
  */
 #define rcu_dereference_bh(p) \
-		rcu_dereference_check(p, rcu_read_lock_bh_held())
+		rcu_dereference_check(p, rcu_read_lock_bh_held() || irqs_disabled())
 
 /**
  * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched