linux-kernel - [PATCH 5.10 94/96] ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210816125438.114351211@linuxfoundation.org>
Date:   Mon, 16 Aug 2021 15:02:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeff Layton <jlayton@...nel.org>,
        Ilya Dryomov <idryomov@...il.com>
Subject: [PATCH 5.10 94/96] ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm

From: Jeff Layton <jlayton@...nel.org>

commit df2c0cb7f8e8c83e495260ad86df8c5da947f2a7 upstream.

They both say that the snap_rwsem must be held for write, but I don't
see any real reason for it, and it's not currently always called that
way.

The lookup is just walking the rbtree, so holding it for read should be
fine there. The "get" is bumping the refcount and (possibly) removing
it from the empty list. I see no need to hold the snap_rwsem for write
for that.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
Reviewed-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/ceph/snap.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -60,12 +60,12 @@
 /*
  * increase ref count for the realm
  *
- * caller must hold snap_rwsem for write.
+ * caller must hold snap_rwsem.
  */
 void ceph_get_snap_realm(struct ceph_mds_client *mdsc,
 			 struct ceph_snap_realm *realm)
 {
-	lockdep_assert_held_write(&mdsc->snap_rwsem);
+	lockdep_assert_held(&mdsc->snap_rwsem);
 
 	dout("get_realm %p %d -> %d\n", realm,
 	     atomic_read(&realm->nref), atomic_read(&realm->nref)+1);
@@ -139,7 +139,7 @@ static struct ceph_snap_realm *ceph_crea
 /*
  * lookup the realm rooted at @ino.
  *
- * caller must hold snap_rwsem for write.
+ * caller must hold snap_rwsem.
  */
 static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc,
 						   u64 ino)
@@ -147,7 +147,7 @@ static struct ceph_snap_realm *__lookup_
 	struct rb_node *n = mdsc->snap_realms.rb_node;
 	struct ceph_snap_realm *r;
 
-	lockdep_assert_held_write(&mdsc->snap_rwsem);
+	lockdep_assert_held(&mdsc->snap_rwsem);
 
 	while (n) {
 		r = rb_entry(n, struct ceph_snap_realm, node);