[tip:core/rcu] security: Apply lockdep-based checking to rcu_dereference() uses

[tip-bot for Paul E. McKenney]

Commit-ID:  e7b0a61b7929632d36cf052d9e2820ef0a9c1bfe
Gitweb:     http://git.kernel.org/tip/e7b0a61b7929632d36cf052d9e2820ef0a9c1bfe
Author:     Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 22 Feb 2010 17:04:56 -0800
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 25 Feb 2010 10:34:52 +0100

security: Apply lockdep-based checking to rcu_dereference() uses

Apply lockdep-ified RCU primitives to key_gc_keyring() and
keyring_destroy().

Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: laijs@xxxxxxxxxxxxxx
Cc: dipankar@xxxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxx
Cc: josh@xxxxxxxxxxxxxxxx
Cc: dvhltc@xxxxxxxxxx
Cc: niv@xxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: Valdis.Kletnieks@xxxxxx
Cc: dhowells@xxxxxxxxxx
LKML-Reference: <1266887105-1528-12-git-send-email-paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 security/keys/gc.c      |    3 ++-
 security/keys/keyring.c |    4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/security/keys/gc.c b/security/keys/gc.c
index 4770be3..1990231 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -77,7 +77,8 @@ static bool key_gc_keyring(struct key *keyring, time_t limit)
 		goto dont_gc;
 
 	/* scan the keyring looking for dead keys */
-	klist = rcu_dereference(keyring->payload.subscriptions);
+	klist = rcu_dereference_check(keyring->payload.subscriptions,
+				      lockdep_is_held(&key_serial_lock));
 	if (!klist)
 		goto dont_gc;
 
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 8ec0274..e814d21 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -151,7 +151,9 @@ static void keyring_destroy(struct key *keyring)
 		write_unlock(&keyring_name_lock);
 	}
 
-	klist = rcu_dereference(keyring->payload.subscriptions);
+	klist = rcu_dereference_check(keyring->payload.subscriptions,
+				      rcu_read_lock_held() ||
+				      atomic_read(&keyring->usage) == 0);
 	if (klist) {
 		for (loop = klist->nkeys - 1; loop >= 0; loop--)
 			key_put(klist->keys[loop]);
--
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