[PATCH net-next] tun: fix build warnings

[Jason Wang]

Stephen Rothwell reports a build warnings(powerpc ppc64_defconfig)

drivers/net/tun.c: In function 'tun_do_read.part.5':
/home/sfr/next/next/drivers/net/tun.c:1491:6: warning: 'err' may be
used uninitialized in this function [-Wmaybe-uninitialized]
   int err;

This is because tun_ring_recv() may return an uninitialized err, fix this.

Reported-by: Stephen Rothwell <s...@canb.auug.org.au>
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/net/tun.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7475215..5eadb7a 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1447,12 +1447,13 @@ static struct sk_buff *tun_ring_recv(struct tun_file 
*tfile, int noblock,
 {
        DECLARE_WAITQUEUE(wait, current);
        struct sk_buff *skb = NULL;
+       int error = 0;
 
        skb = skb_array_consume(&tfile->tx_array);
        if (skb)
                goto out;
        if (noblock) {
-               *err = -EAGAIN;
+               error = -EAGAIN;
                goto out;
        }
 
@@ -1464,11 +1465,11 @@ static struct sk_buff *tun_ring_recv(struct tun_file 
*tfile, int noblock,
                if (skb)
                        break;
                if (signal_pending(current)) {
-                       *err = -ERESTARTSYS;
+                       error = -ERESTARTSYS;
                        break;
                }
                if (tfile->socket.sk->sk_shutdown & RCV_SHUTDOWN) {
-                       *err = -EFAULT;
+                       error = -EFAULT;
                        break;
                }
 
@@ -1479,6 +1480,7 @@ static struct sk_buff *tun_ring_recv(struct tun_file 
*tfile, int noblock,
        remove_wait_queue(&tfile->wq.wait, &wait);
 
 out:
+       *err = error;
        return skb;
 }
 
-- 
2.7.4