libceph: just set SOCK_CLOSED when state changes

When a TCP_CLOSE or TCP_CLOSE_WAIT event occurs, the SOCK_CLOSED
connection flag bit is set, and if it had not been previously set
queue_con() is called to ensure con_work() will get a chance to
handle the changed state.

con_work() atomically checks--and if set, clears--the SOCK_CLOSED
bit if it was set.  This means that even if the bit were set
repeatedly, the related processing in con_work() only gets called
once per transition of the bit from 0 to 1.

What's important then is that we ensure con_work() gets called *at
least* once when a socket close event occurs, not that it gets
called *exactly* once.

The work queue mechanism already takes care of queueing work
only if it is not already queued, so there's no need for us
to call queue_con() conditionally.

So this patch just makes it so the SOCK_CLOSED flag gets set
unconditionally in ceph_sock_state_change().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -261,8 +261,8 @@ static void ceph_sock_state_change(struct sock *sk)
 	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))
-			queue_con(con);
+		set_bit(SOCK_CLOSED, &con->flags);
+		queue_con(con);
 		break;
 	case TCP_ESTABLISHED:
 		dout("%s TCP_ESTABLISHED\n", __func__);