Simplify/clarify branching and locking in several places

diff --git a/module/can327.c b/module/can327.c
index 803a9ab79214ceee3ed0d1f74562acf1fca47134..97ca7e148d334607dddbb7dfe02804d6e04c4374 100644 (file)
--- a/module/can327.c
+++ b/module/can327.c
@@ -856,25 +856,26 @@ static netdev_tx_t can327_netdev_start_xmit(struct sk_buff *skb,
        if (can_dropped_invalid_skb(dev, skb))
                return NETDEV_TX_OK;
 
-       /* BHs are already disabled, so no spin_lock_bh().
-        * See Documentation/networking/netdevices.txt
+       /* This check will be part of can_dropped_invalid_skb()
+        * in future kernels.
         */
-       spin_lock(&elm->lock);
+       if (elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+               goto out;
 
        /* We shouldn't get here after a hardware fault:
         * can_bus_off() calls netif_carrier_off()
         */
-       WARN_ON_ONCE(elm->uart_side_failure);
-
-       if (!elm->tty ||
-           elm->uart_side_failure ||
-           elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
-               spin_unlock(&elm->lock);
+       if (elm->uart_side_failure) {
+               WARN_ON_ONCE(elm->uart_side_failure);
                goto out;
        }
 
        netif_stop_queue(dev);
 
+       /* BHs are already disabled, so no spin_lock_bh().
+        * See Documentation/networking/netdevices.txt
+        */
+       spin_lock(&elm->lock);
        elm327_send_frame(elm, frame);
        spin_unlock(&elm->lock);
 
@@ -925,10 +926,10 @@ static void can327_ldisc_rx(struct tty_struct *tty,
 {
        struct can327 *elm = (struct can327 *)tty->disc_data;
 
-       spin_lock_bh(&elm->lock);
-
        if (elm->uart_side_failure)
-               goto out;
+               return;
+
+       spin_lock_bh(&elm->lock);
 
        while (count-- && elm->rxfill < ELM327_SIZE_RXBUF) {
                if (fp && *fp++) {
@@ -936,7 +937,8 @@ static void can327_ldisc_rx(struct tty_struct *tty,
 
                        elm327_uart_side_failure(elm);
 
-                       goto out;
+                       spin_unlock_bh(&elm->lock);
+                       return;
                }
 
                /* Ignore NUL characters, which the PIC microcontroller may
@@ -954,7 +956,8 @@ static void can327_ldisc_rx(struct tty_struct *tty,
                                           *cp);
                                elm327_uart_side_failure(elm);
 
-                               goto out;
+                               spin_unlock_bh(&elm->lock);
+                               return;
                        }
 
                        elm->rxbuf[elm->rxfill++] = *cp;
@@ -968,12 +971,11 @@ static void can327_ldisc_rx(struct tty_struct *tty,
 
                elm327_uart_side_failure(elm);
 
-               goto out;
+               spin_unlock_bh(&elm->lock);
+               return;
        }
 
        elm327_parse_rxbuf(elm);
-
-out:
        spin_unlock_bh(&elm->lock);
 }
 
@@ -997,6 +999,7 @@ static void can327_ldisc_tx_worker(struct work_struct *work)
                                   "Failed to write to tty %s.\n",
                                   elm->tty->name);
                        elm327_uart_side_failure(elm);
+
                        spin_unlock_bh(&elm->lock);
                        return;
                }
@@ -1005,12 +1008,10 @@ static void can327_ldisc_tx_worker(struct work_struct *work)
                elm->txhead += written;
        }
 
-       if (!elm->txleft)  {
+       if (!elm->txleft)
                clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
-               spin_unlock_bh(&elm->lock);
-       } else {
-               spin_unlock_bh(&elm->lock);
-       }
+
+       spin_unlock_bh(&elm->lock);
 }
 
 /* Called by the driver when there's room for more data. */
@@ -1082,16 +1083,14 @@ static int can327_ldisc_open(struct tty_struct *tty)
 
        /* Let 'er rip */
        err = register_candev(elm->dev);
-       if (err)
-               goto out_err;
+       if (err) {
+               free_candev(elm->dev);
+               return err;
+       }
 
        netdev_info(elm->dev, "can327 on %s.\n", tty->name);
 
        return 0;
-
-out_err:
-       free_candev(elm->dev);
-       return err;
 }
 
 /* Close down a can327 channel.