libceph: a few small changes

This gathers a number of very minor changes:
    - use %hu when formatting the a socket address's address family
    - null out the ceph_msgr_wq pointer after the queue has been
      destroyed
    - drop a needless cast in ceph_write_space()
    - add a WARN() call in ceph_state_change() in the event an
      unrecognized socket state is encountered
    - rearrange the logic in ceph_con_get() and ceph_con_put() so
      that:
        - the reference counts are only atomically read once
	- the values displayed via dout() calls are known to
	  be meaningful at the time they are formatted

Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index e1e53bb..44d8c77 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -80,8 +80,8 @@ const char *ceph_pr_addr(const struct sockaddr_storage *ss)
                break;
 
        default:
-               snprintf(s, MAX_ADDR_STR_LEN, "(unknown sockaddr family %d)",
-                        (int)ss->ss_family);
+               snprintf(s, MAX_ADDR_STR_LEN, "(unknown sockaddr family %hu)",
+                        ss->ss_family);
        }
 
        return s;
@@ -101,8 +101,10 @@ static struct workqueue_struct *ceph_msgr_wq;
 
 void _ceph_msgr_exit(void)
 {
-       if (ceph_msgr_wq)
+       if (ceph_msgr_wq) {
                destroy_workqueue(ceph_msgr_wq);
+               ceph_msgr_wq = NULL;
+       }
 
        BUG_ON(zero_page_address == NULL);
        zero_page_address = NULL;
@@ -167,8 +169,7 @@ static void ceph_data_ready(struct sock *sk, int count_unused)
 /* socket has buffer space for writing */
 static void ceph_write_space(struct sock *sk)
 {
-       struct ceph_connection *con =
-               (struct ceph_connection *)sk->sk_user_data;
+       struct ceph_connection *con = sk->sk_user_data;
 
        /* only queue to workqueue if there is data we want to write,
         * and there is sufficient space in the socket buffer to accept
@@ -216,6 +217,8 @@ static void ceph_state_change(struct sock *sk)
                dout("ceph_state_change TCP_ESTABLISHED\n");
                queue_con(con);
                break;
+       default:        /* Everything else is uninteresting */
+               break;
        }
 }
 
@@ -420,22 +423,23 @@ bool ceph_con_opened(struct ceph_connection *con)
  */
 struct ceph_connection *ceph_con_get(struct ceph_connection *con)
 {
-       dout("con_get %p nref = %d -> %d\n", con,
-            atomic_read(&con->nref), atomic_read(&con->nref) + 1);
-       if (atomic_inc_not_zero(&con->nref))
-               return con;
-       return NULL;
+       int nref = __atomic_add_unless(&con->nref, 1, 0);
+
+       dout("con_get %p nref = %d -> %d\n", con, nref, nref + 1);
+
+       return nref ? con : NULL;
 }
 
 void ceph_con_put(struct ceph_connection *con)
 {
-       dout("con_put %p nref = %d -> %d\n", con,
-            atomic_read(&con->nref), atomic_read(&con->nref) - 1);
-       BUG_ON(atomic_read(&con->nref) == 0);
-       if (atomic_dec_and_test(&con->nref)) {
+       int nref = atomic_dec_return(&con->nref);
+
+       BUG_ON(nref < 0);
+       if (nref == 0) {
                BUG_ON(con->sock);
                kfree(con);
        }
+       dout("con_put %p nref = %d -> %d\n", con, nref + 1, nref);
 }
 
 /*