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* [PATCH RESEND] device_cgroup: Fix RCU list debugging warning
@ 2020-04-06 10:59 Amol Grover
  2020-06-06 20:23 ` Stephen Rothwell
  0 siblings, 1 reply; 7+ messages in thread
From: Amol Grover @ 2020-04-06 10:59 UTC (permalink / raw)
  To: James Morris, Serge E . Hallyn
  Cc: linux-kernel, linux-kernel-mentees, Joel Fernandes,
	Madhuparna Bhowmik, Paul E . McKenney, linux-security-module,
	Amol Grover

exceptions may be traversed using list_for_each_entry_rcu()
outside of an RCU read side critical section BUT under the
protection of decgroup_mutex. Hence add the corresponding
lockdep expression to fix the following false-positive
warning:

[    2.304417] =============================
[    2.304418] WARNING: suspicious RCU usage
[    2.304420] 5.5.4-stable #17 Tainted: G            E
[    2.304422] -----------------------------
[    2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 security/device_cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 7d0f8f7431ff..b7da9e0970d9 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head *exceptions, short type,
 {
 	struct dev_exception_item *ex;
 
-	list_for_each_entry_rcu(ex, exceptions, list) {
+	list_for_each_entry_rcu(ex, exceptions, list,
+				lockdep_is_held(&devcgroup_mutex)) {
 		if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
 			continue;
 		if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
-- 
2.24.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2020-08-20 22:38 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-04-06 10:59 [PATCH RESEND] device_cgroup: Fix RCU list debugging warning Amol Grover
2020-06-06 20:23 ` Stephen Rothwell
2020-06-07 19:08   ` Paul E. McKenney
2020-06-08  4:17     ` Serge E. Hallyn
2020-08-17  2:07       ` Stephen Rothwell
2020-08-20 18:28         ` James Morris
2020-08-20 22:38           ` Stephen Rothwell

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