Thread (1 message) 1 message, 1 author, 2013-10-09
STALE4675d

[PATCH v2 tip/core/rcu 13/13] bonding/bond_alb.c: Apply rcu_access_pointer() to avoid sparse false positive

From: Paul E. McKenney <hidden>
Date: 2013-10-09 21:33:17
Also in: lkml
Subsystem: bonding driver, networking drivers, the rest · Maintainers: Jay Vosburgh, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

From: "Paul E. McKenney" <redacted>

The sparse checking for rcu_assign_pointer() was recently upgraded
to reject non-__kernel address spaces.  This also rejects __rcu,
which is almost always the right thing to do.  However, the use in
bond_alb_handle_active_change() is legitimate: It is assigning a pointer
to an element from an RCU-protected list, and all elements of this list
are already visible to caller.

This commit therefore silences this false positive by laundering the
pointer using rcu_access_pointer() as suggested by Josh Triplett.

Reported-by: kbuild test robot <redacted>
Signed-off-by: Paul E. McKenney <redacted>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <redacted>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <redacted>
Cc: Patrick McHardy <redacted>
Cc: netdev@vger.kernel.org
---
 drivers/net/bonding/bond_alb.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c
index 91f179d5135c..cdd697cca6b5 100644
--- a/drivers/net/bonding/bond_alb.c
+++ b/drivers/net/bonding/bond_alb.c
@@ -1667,7 +1667,8 @@ void bond_alb_handle_active_change(struct bonding *bond, struct slave *new_slave
 	}
 
 	swap_slave = bond->curr_active_slave;
-	rcu_assign_pointer(bond->curr_active_slave, new_slave);
+	rcu_assign_pointer(bond->curr_active_slave,
+			   rcu_access_pointer(new_slave));
 
 	if (!new_slave || list_empty(&bond->slave_list))
 		return;
-- 
1.8.1.5
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help