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Commit a6a5349d authored by Sage Weil's avatar Sage Weil
Browse files

ceph: use separate class for ceph sockets' sk_lock 



Use a separate class for ceph sockets to prevent lockdep confusion.
Because ceph sockets only get passed kernel pointers, there is no
dependency from sk_lock -> mmap_sem.  If we share the same class as other
sockets, lockdep detects a circular dependency from

	mmap_sem (page fault) -> fs mutex -> sk_lock -> mmap_sem

because dependencies are noted from both ceph and user contexts.  Using
a separate class prevents the sk_lock(ceph) -> mmap_sem dependency and
makes lockdep happy.

Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent e1e4dd0c

fs/ceph/messenger.c

+8 −0
Original line number Diff line number Diff line
@@ -29,6 +29,10 @@ static char tag_msg = CEPH_MSGR_TAG_MSG; 
static char tag_ack = CEPH_MSGR_TAG_ACK;

static char tag_keepalive = CEPH_MSGR_TAG_KEEPALIVE;



#ifdef CONFIG_LOCKDEP

static struct lock_class_key socket_class;

#endif





static void queue_con(struct ceph_connection *con);

static void con_work(struct work_struct *);
@@ -227,6 +231,10 @@ static struct socket *ceph_tcp_connect(struct ceph_connection *con) 
	con->sock = sock;

	sock->sk->sk_allocation = GFP_NOFS;



#ifdef CONFIG_LOCKDEP

	lockdep_set_class(&sock->sk->sk_lock, &socket_class);

#endif



	set_sock_callbacks(sock, con);



	dout("connect %s\n", pr_addr(&con->peer_addr.in_addr));