lkml.org 
[lkml]   [2013]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 tip/core/rcu 02/13] notifiers: Apply rcu_access_pointer() to avoid sparse false positive
Date
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

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
notifier_chain_unregister() is legitimate: It is deleting 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 <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/notifier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/notifier.c b/kernel/notifier.c
index 2d5cc4ccff7f..1857c71bae40 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -51,7 +51,7 @@ static int notifier_chain_unregister(struct notifier_block **nl,
{
while ((*nl) != NULL) {
if ((*nl) == n) {
- rcu_assign_pointer(*nl, n->next);
+ rcu_assign_pointer(*nl, rcu_access_pointer(n->next));
return 0;
}
nl = &((*nl)->next);
--
1.8.1.5


\
 
 \ /
  Last update: 2013-10-10 00:21    [W:0.174 / U:0.452 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site