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device_cgroup: Fix RCU list debugging warning

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[ Upstream commit bc62d68e2a0a69fcdcf28aca8edb01abf306b698 ]

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>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Amol Grover 2020-04-06 16:29:50 +05:30 committed by Greg Kroah-Hartman
parent 5b84cd71c1
commit 8ebf2b77d7
1 changed files with 2 additions and 1 deletions
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security/device_cgroup.c
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@ -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))