On Tue, 12 Jun 2012, Yan, Zheng wrote:
> On Thu, May 31, 2012 at 3:35 AM, Alex Elder <[email protected]> wrote:
> > Start explicitly keeping track of the state of a ceph connection's
> > socket, separate from the state of the connection itself. Create
> > placeholder functions to encapsulate the state transitions.
> >
> > --------
> > | NEW* | transient initial state
> > --------
> > | con_sock_state_init()
> > v
> > ----------
> > | CLOSED | initialized, but no socket (and no
> > ---------- TCP connection)
> > ^ \
> > | \ con_sock_state_connecting()
> > | ----------------------
> > | \
> > + con_sock_state_closed() \
> > |\ \
> > | \ \
> > | ----------- \
> > | | CLOSING | socket event; \
> > | ----------- await close \
> > | ^ |
> > | | |
> > | + con_sock_state_closing() |
> > | / \ |
> > | / --------------- |
> > | / \ v
> > | / --------------
> > | / -----------------| CONNECTING | socket created, TCP
> > | | / -------------- connect initiated
> > | | | con_sock_state_connected()
> > | | v
> > -------------
> > | CONNECTED | TCP connection established
> > -------------
> >
> > Make the socket state an atomic variable, reinforcing that it's a
> > distinct transtion with no possible "intermediate/both" states.
> > This is almost certainly overkill at this point, though the
> > transitions into CONNECTED and CLOSING state do get called via
> > socket callback (the rest of the transitions occur with the
> > connection mutex held). We can back out the atomicity later.
> >
> > Signed-off-by: Alex Elder <[email protected]>
> > ---
> > include/linux/ceph/messenger.h | 8 ++++-
> > net/ceph/messenger.c | 63
> > ++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 69 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
> > index 920235e..5e852f4 100644
> > --- a/include/linux/ceph/messenger.h
> > +++ b/include/linux/ceph/messenger.h
> > @@ -137,14 +137,18 @@ struct ceph_connection {
> > const struct ceph_connection_operations *ops;
> >
> > struct ceph_messenger *msgr;
> > +
> > + atomic_t sock_state;
> > struct socket *sock;
> > + struct ceph_entity_addr peer_addr; /* peer address */
> > + struct ceph_entity_addr peer_addr_for_me;
> > +
> > unsigned long flags;
> > unsigned long state;
> > const char *error_msg; /* error message, if any */
> >
> > - struct ceph_entity_addr peer_addr; /* peer address */
> > struct ceph_entity_name peer_name; /* peer name */
> > - struct ceph_entity_addr peer_addr_for_me;
> > +
> > unsigned peer_features;
> > u32 connect_seq; /* identify the most recent connection
> > attempt for this connection, client */
> > diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> > index 29055df..7e11b07 100644
> > --- a/net/ceph/messenger.c
> > +++ b/net/ceph/messenger.c
> > @@ -29,6 +29,14 @@
> > * the sender.
> > */
> >
> > +/* State values for ceph_connection->sock_state; NEW is assumed to be 0 */
> > +
> > +#define CON_SOCK_STATE_NEW 0 /* -> CLOSED */
> > +#define CON_SOCK_STATE_CLOSED 1 /* -> CONNECTING */
> > +#define CON_SOCK_STATE_CONNECTING 2 /* -> CONNECTED or ->
> > CLOSING */
> > +#define CON_SOCK_STATE_CONNECTED 3 /* -> CLOSING or -> CLOSED
> > */
> > +#define CON_SOCK_STATE_CLOSING 4 /* -> CLOSED */
> > +
> > /* static tag bytes (protocol control messages) */
> > static char tag_msg = CEPH_MSGR_TAG_MSG;
> > static char tag_ack = CEPH_MSGR_TAG_ACK;
> > @@ -147,6 +155,54 @@ void ceph_msgr_flush(void)
> > }
> > EXPORT_SYMBOL(ceph_msgr_flush);
> >
> > +/* Connection socket state transition functions */
> > +
> > +static void con_sock_state_init(struct ceph_connection *con)
> > +{
> > + int old_state;
> > +
> > + old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSED);
> > + if (WARN_ON(old_state != CON_SOCK_STATE_NEW))
> > + printk("%s: unexpected old state %d\n", __func__,
> > old_state);
> > +}
> > +
> > +static void con_sock_state_connecting(struct ceph_connection *con)
> > +{
> > + int old_state;
> > +
> > + old_state = atomic_xchg(&con->sock_state,
> > CON_SOCK_STATE_CONNECTING);
> > + if (WARN_ON(old_state != CON_SOCK_STATE_CLOSED))
> > + printk("%s: unexpected old state %d\n", __func__,
> > old_state);
> > +}
> > +
> > +static void con_sock_state_connected(struct ceph_connection *con)
> > +{
> > + int old_state;
> > +
> > + old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CONNECTED);
> > + if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTING))
> > + printk("%s: unexpected old state %d\n", __func__,
> > old_state);
> > +}
> > +
> > +static void con_sock_state_closing(struct ceph_connection *con)
> > +{
> > + int old_state;
> > +
> > + old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSING);
> > + if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTING &&
> > + old_state != CON_SOCK_STATE_CONNECTED))
> > + printk("%s: unexpected old state %d\n", __func__,
> > old_state);
> > +}
> > +
> > +static void con_sock_state_closed(struct ceph_connection *con)
> > +{
> > + int old_state;
> > +
> > + old_state = atomic_xchg(&con->sock_state, CON_SOCK_STATE_CLOSED);
> > + if (WARN_ON(old_state != CON_SOCK_STATE_CONNECTED &&
> > + old_state != CON_SOCK_STATE_CLOSING))
> > + printk("%s: unexpected old state %d\n", __func__,
> > old_state);
> > +}
> >
> Hi Alex,
>
> Single node setup can easily trigger above WARN_ON. I think this is because
> local TCP connection setup and shutdown is very fast, they finish immediately
> after sock->connect and sock->shutdown return.
Yep. This was just fixed yesterday, in the testing-next branch, by
'libceph: transition socket state prior to actual connect'.
Are you still hitting the bio null deref?
Thanks-
sage
>
> Yan, Zheng
>
> > /*
> > * socket callback functions
> > @@ -203,6 +259,7 @@ static void ceph_sock_state_change(struct sock *sk)
> > dout("%s TCP_CLOSE\n", __func__);
> > case TCP_CLOSE_WAIT:
> > dout("%s TCP_CLOSE_WAIT\n", __func__);
> > + con_sock_state_closing(con);
> > if (test_and_set_bit(SOCK_CLOSED, &con->flags) == 0) {
> > if (test_bit(CONNECTING, &con->state))
> > con->error_msg = "connection failed";
> > @@ -213,6 +270,7 @@ static void ceph_sock_state_change(struct sock *sk)
> > break;
> > case TCP_ESTABLISHED:
> > dout("%s TCP_ESTABLISHED\n", __func__);
> > + con_sock_state_connected(con);
> > queue_con(con);
> > break;
> > default: /* Everything else is uninteresting */
> > @@ -277,6 +335,7 @@ static int ceph_tcp_connect(struct ceph_connection *con)
> > return ret;
> > }
> > con->sock = sock;
> > + con_sock_state_connecting(con);
> >
> > return 0;
> > }
> > @@ -341,6 +400,7 @@ static int con_close_socket(struct ceph_connection *con)
> > rc = con->sock->ops->shutdown(con->sock, SHUT_RDWR);
> > sock_release(con->sock);
> > con->sock = NULL;
> > + con_sock_state_closed(con);
> > return rc;
> > }
> >
> > @@ -460,6 +520,9 @@ void ceph_con_init(struct ceph_messenger *msgr, struct
> > ceph_connection *con)
> > memset(con, 0, sizeof(*con));
> > atomic_set(&con->nref, 1);
> > con->msgr = msgr;
> > +
> > + con_sock_state_init(con);
> > +
> > mutex_init(&con->mutex);
> > INIT_LIST_HEAD(&con->out_queue);
> > INIT_LIST_HEAD(&con->out_sent);
> > --
> > 1.7.5.4
> >
> > --
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