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* [Linux-kernel-mentees] [PATCH RESEND] device_cgroup: Fix RCU list debugging warning
@ 2020-04-06 10:59 ` Amol Grover
  0 siblings, 0 replies; 14+ messages in thread
From: Amol Grover @ 2020-04-06 10:59 UTC (permalink / raw)
  To: James Morris, Serge E . Hallyn
  Cc: Paul E . McKenney, linux-kernel, Madhuparna Bhowmik,
	linux-security-module, Joel Fernandes, linux-kernel-mentees

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

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^ permalink raw reply related	[flat|nested] 14+ messages in thread

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

Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-04-06 10:59 [Linux-kernel-mentees] [PATCH RESEND] device_cgroup: Fix RCU list debugging warning Amol Grover
2020-04-06 10:59 ` Amol Grover
2020-06-06 20:23 ` [Linux-kernel-mentees] " Stephen Rothwell
2020-06-06 20:23   ` Stephen Rothwell
2020-06-07 19:08   ` [Linux-kernel-mentees] " Paul E. McKenney
2020-06-07 19:08     ` Paul E. McKenney
2020-06-08  4:17     ` [Linux-kernel-mentees] " Serge E. Hallyn
2020-06-08  4:17       ` Serge E. Hallyn
2020-08-17  2:07       ` [Linux-kernel-mentees] " Stephen Rothwell
2020-08-17  2:07         ` Stephen Rothwell
2020-08-20 18:28         ` [Linux-kernel-mentees] " James Morris
2020-08-20 18:28           ` James Morris
2020-08-20 22:38           ` [Linux-kernel-mentees] " Stephen Rothwell
2020-08-20 22:38             ` Stephen Rothwell

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