[PATCH net] drivers/net/wan: lapb: Replace the skb->len checks with pskb_may_pull

[Xie He]

The purpose of these skb->len checks in these drivers is to ensure that
there is a header in the skb available to be read and pulled.

However, we already have the pskb_may_pull function for this purpose.

The pskb_may_pull function also correctly handles non-linear skbs.

(Also delete the word "check" in the comments because pskb_may_pull may
do things other than simple checks in the case of non-linear skbs.)

Cc: Willem de Bruijn <willemdebruijn.ker...@gmail.com>
Cc: Martin Schiller <m...@dev.tdt.de>
Signed-off-by: Xie He <xie.he.0...@gmail.com>
---
 drivers/net/wan/hdlc_x25.c  | 4 ++--
 drivers/net/wan/lapbether.c | 4 ++--
 drivers/net/wan/x25_asy.c   | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wan/hdlc_x25.c b/drivers/net/wan/hdlc_x25.c
index f52b9fed0593..891a7a918b29 100644
--- a/drivers/net/wan/hdlc_x25.c
+++ b/drivers/net/wan/hdlc_x25.c
@@ -108,9 +108,9 @@ static netdev_tx_t x25_xmit(struct sk_buff *skb, struct 
net_device *dev)
        int result;
 
        /* There should be a pseudo header of 1 byte added by upper layers.
-        * Check to make sure it is there before reading it.
+        * Make sure it is there before reading it.
         */
-       if (skb->len < 1) {
+       if (!pskb_may_pull(skb, 1)) {
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
index b6be2454b8bd..e0cf692357d6 100644
--- a/drivers/net/wan/lapbether.c
+++ b/drivers/net/wan/lapbether.c
@@ -158,9 +158,9 @@ static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
                goto drop;
 
        /* There should be a pseudo header of 1 byte added by upper layers.
-        * Check to make sure it is there before reading it.
+        * Make sure it is there before reading it.
         */
-       if (skb->len < 1)
+       if (!pskb_may_pull(skb, 1))
                goto drop;
 
        switch (skb->data[0]) {
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index c418767a890a..b935a3e1d5f6 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -308,9 +308,9 @@ static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
        }
 
        /* There should be a pseudo header of 1 byte added by upper layers.
-        * Check to make sure it is there before reading it.
+        * Make sure it is there before reading it.
         */
-       if (skb->len < 1) {
+       if (!pskb_may_pull(skb, 1)) {
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }
-- 
2.25.1