RDS: rds_send_xmit() locking/irq fixes
Andy Grover [Wed, 24 Mar 2010 00:48:04 +0000 (17:48 -0700)]
rds_message_put() cannot be called with irqs off, so move it after
irqs are re-enabled.

Spinlocks throughout the function do not to use _irqsave because
the lock of c_send_lock at top already disabled irqs.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

net/rds/send.c

index d4feec6..624a3dc 100644 (file)
@@ -168,7 +168,7 @@ int rds_send_xmit(struct rds_connection *conn)
                if (!rm) {
                        unsigned int len;
 
-                       spin_lock_irqsave(&conn->c_lock, flags);
+                       spin_lock(&conn->c_lock);
 
                        if (!list_empty(&conn->c_send_queue)) {
                                rm = list_entry(conn->c_send_queue.next,
@@ -183,7 +183,7 @@ int rds_send_xmit(struct rds_connection *conn)
                                list_move_tail(&rm->m_conn_item, &conn->c_retrans);
                        }
 
-                       spin_unlock_irqrestore(&conn->c_lock, flags);
+                       spin_unlock(&conn->c_lock);
 
                        if (!rm) {
                                was_empty = 1;
@@ -199,11 +199,10 @@ int rds_send_xmit(struct rds_connection *conn)
                         */
                        if (rm->rdma.op_active &&
                            test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
-                               spin_lock_irqsave(&conn->c_lock, flags);
+                               spin_lock(&conn->c_lock);
                                if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
                                        list_move(&rm->m_conn_item, &to_be_dropped);
-                               spin_unlock_irqrestore(&conn->c_lock, flags);
-                               rds_message_put(rm);
+                               spin_unlock(&conn->c_lock);
                                continue;
                        }
 
@@ -326,10 +325,6 @@ int rds_send_xmit(struct rds_connection *conn)
                }
        }
 
-       /* Nuke any messages we decided not to retransmit. */
-       if (!list_empty(&to_be_dropped))
-               rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
-
        if (conn->c_trans->xmit_complete)
                conn->c_trans->xmit_complete(conn);
 
@@ -347,6 +342,14 @@ int rds_send_xmit(struct rds_connection *conn)
         */
        spin_unlock_irqrestore(&conn->c_send_lock, flags);
 
+       /* Nuke any messages we decided not to retransmit. */
+       if (!list_empty(&to_be_dropped)) {
+               /* irqs on here, so we can put(), unlike above */
+               list_for_each_entry(rm, &to_be_dropped, m_conn_item)
+                       rds_message_put(rm);
+               rds_send_remove_from_sock(&to_be_dropped, RDS_RDMA_DROPPED);
+       }
+
        if (send_quota == 0 && !was_empty) {
                /* We exhausted the send quota, but there's work left to
                 * do. Return and (re-)schedule the send worker.