Fix Smatch warnings.
- lan78xx.c:2282 tx_complete() warn: variable dereferenced before check 'skb' 
(see line 2249)
- lan78xx.c:2885 lan78xx_bh() info: ignoring unreachable code.
- lan78xx.c:3159 lan78xx_probe() info: ignoring unreachable code.

Reported-by: Dan Carpenter <dan.carpen...@oracle.com>

Signed-off-by: Woojung Huh <woojung....@microchip.com>
---
 drivers/net/usb/lan78xx.c | 52 ++++++++++++++++++++++-------------------------
 1 file changed, 24 insertions(+), 28 deletions(-)

diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index ec8bd34..3ac405f 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -291,7 +291,7 @@ static int lan78xx_read_reg(struct lan78xx_net *dev, u32 
index, u32 *data)
        u32 *buf = kmalloc(sizeof(u32), GFP_KERNEL);
        int ret;
 
-       BUG_ON(!dev);
+       WARN_ON_ONCE(!dev);
 
        if (!buf)
                return -ENOMEM;
@@ -319,7 +319,7 @@ static int lan78xx_write_reg(struct lan78xx_net *dev, u32 
index, u32 data)
        u32 *buf = kmalloc(sizeof(u32), GFP_KERNEL);
        int ret;
 
-       BUG_ON(!dev);
+       WARN_ON_ONCE(!dev);
 
        if (!buf)
                return -ENOMEM;
@@ -351,9 +351,9 @@ static int lan78xx_read_stats(struct lan78xx_net *dev,
        u32 *src;
        u32 *dst;
 
-       BUG_ON(!dev);
-       BUG_ON(!data);
-       BUG_ON(sizeof(struct lan78xx_statstage) != 0xBC);
+       WARN_ON_ONCE(!dev);
+       WARN_ON_ONCE(!data);
+       WARN_ON_ONCE(sizeof(struct lan78xx_statstage) != 0xBC);
 
        stats = kmalloc(sizeof(*stats), GFP_KERNEL);
        if (!stats)
@@ -687,8 +687,8 @@ static int lan78xx_read_raw_eeprom(struct lan78xx_net *dev, 
u32 offset,
        u32 val;
        int i, ret;
 
-       BUG_ON(!dev);
-       BUG_ON(!data);
+       WARN_ON_ONCE(!dev);
+       WARN_ON_ONCE(!data);
 
        ret = lan78xx_eeprom_confirm_not_busy(dev);
        if (ret)
@@ -737,8 +737,8 @@ static int lan78xx_write_raw_eeprom(struct lan78xx_net 
*dev, u32 offset,
        u32 val;
        int i, ret;
 
-       BUG_ON(!dev);
-       BUG_ON(!data);
+       WARN_ON_ONCE(!dev);
+       WARN_ON_ONCE(!data);
 
        ret = lan78xx_eeprom_confirm_not_busy(dev);
        if (ret)
@@ -2221,19 +2221,19 @@ static enum skb_state defer_bh(struct lan78xx_net *dev, 
struct sk_buff *skb,
        old_state = entry->state;
        entry->state = state;
        if (!list->prev)
-               BUG_ON(!list->prev);
+               WARN_ON_ONCE(!list->prev);
        if (!list->next)
-               BUG_ON(!list->next);
+               WARN_ON_ONCE(!list->next);
        if (!skb->prev || !skb->next)
-               BUG_ON(true);
+               WARN_ON_ONCE(true);
 
        __skb_unlink(skb, list);
        spin_unlock(&list->lock);
        spin_lock(&dev->done.lock);
        if (!dev->done.prev)
-               BUG_ON(!dev->done.prev);
+               WARN_ON_ONCE(!dev->done.prev);
        if (!dev->done.next)
-               BUG_ON(!dev->done.next);
+               WARN_ON_ONCE(!dev->done.next);
 
        __skb_queue_tail(&dev->done, skb);
        if (skb_queue_len(&dev->done) == 1)
@@ -2279,8 +2279,7 @@ static void tx_complete(struct urb *urb)
 
        usb_autopm_put_interface_async(dev->intf);
 
-       if (skb)
-               defer_bh(dev, skb, &dev->txq, tx_done);
+       defer_bh(dev, skb, &dev->txq, tx_done);
 }
 
 static void lan78xx_queue_skb(struct sk_buff_head *list,
@@ -2295,13 +2294,15 @@ static void lan78xx_queue_skb(struct sk_buff_head *list,
 netdev_tx_t lan78xx_start_xmit(struct sk_buff *skb, struct net_device *net)
 {
        struct lan78xx_net *dev = netdev_priv(net);
+       struct sk_buff *skb2 = NULL;
 
-       if (skb)
+       if (skb) {
                skb_tx_timestamp(skb);
+               skb2 = lan78xx_tx_prep(dev, skb, GFP_ATOMIC);
+       }
 
-       skb = lan78xx_tx_prep(dev, skb, GFP_ATOMIC);
-       if (skb) {
-               skb_queue_tail(&dev->txq_pend, skb);
+       if (skb2) {
+               skb_queue_tail(&dev->txq_pend, skb2);
 
                if (skb_queue_len(&dev->txq_pend) > 10)
                        netif_stop_queue(net);
@@ -2749,7 +2750,7 @@ static void lan78xx_tx_bh(struct lan78xx_net *dev)
                        pos += roundup(skb2->len, sizeof(u32));
                        dev_kfree_skb(skb2);
                } else {
-                       BUG_ON(true);
+                       WARN_ON_ONCE(true);
                }
        }
 
@@ -2859,9 +2860,9 @@ static void lan78xx_bh(unsigned long param)
        struct skb_data *entry;
 
        if (!dev->done.prev)
-               BUG_ON(!dev->done.prev);
+               WARN_ON_ONCE(!dev->done.prev);
        if (!dev->done.next)
-               BUG_ON(!dev->done.next);
+               WARN_ON_ONCE(!dev->done.next);
 
        while ((skb = skb_dequeue(&dev->done))) {
                entry = (struct skb_data *)(skb->cb);
@@ -2882,10 +2883,6 @@ static void lan78xx_bh(unsigned long param)
                        netdev_dbg(dev->net, "skb state %d\n", entry->state);
                        return;
                }
-               if (!dev->done.prev)
-                       BUG_ON(!dev->done.prev);
-               if (!dev->done.next)
-                       BUG_ON(!dev->done.next);
        }
 
        if (netif_device_present(dev->net) && netif_running(dev->net)) {
@@ -3156,7 +3153,6 @@ static int lan78xx_probe(struct usb_interface *intf,
 
        return 0;
 
-       usb_set_intfdata(intf, NULL);
 out3:
        lan78xx_unbind(dev, intf);
 out2:
-- 
2.1.4

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