macvtap: read vnet_hdr_size once

[pandora-kernel.git] / drivers / net / macvtap.c

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 7300447..1c3db94 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -687,7 +687,7 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
        size_t linear;
 
        if (q->flags & IFF_VNET_HDR) {
-               vnet_hdr_len = q->vnet_hdr_sz;
+               vnet_hdr_len = ACCESS_ONCE(q->vnet_hdr_sz);
 
                err = -EINVAL;
                if (len < vnet_hdr_len)
@@ -720,6 +720,8 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
                copylen = vnet_hdr.hdr_len ? vnet_hdr.hdr_len : GOODCOPY_LEN;
                if (copylen > good_linear)
                        copylen = good_linear;
+               else if (copylen < ETH_HLEN)
+                       copylen = ETH_HLEN;
                linear = copylen;
                if (iov_pages(iv, vnet_hdr_len + copylen, count)
                    <= MAX_SKB_FRAGS)
@@ -728,10 +730,11 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
 
        if (!zerocopy) {
                copylen = len;
-               if (vnet_hdr.hdr_len > good_linear)
+               linear = vnet_hdr.hdr_len;
+               if (linear > good_linear)
                        linear = good_linear;
-               else
-                       linear = vnet_hdr.hdr_len;
+               else if (linear < ETH_HLEN)
+                       linear = ETH_HLEN;
        }
 
        skb = macvtap_alloc_skb(&q->sk, MACVTAP_RESERVE, copylen,
@@ -814,7 +817,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
 
        if (q->flags & IFF_VNET_HDR) {
                struct virtio_net_hdr vnet_hdr;
-               vnet_hdr_len = q->vnet_hdr_sz;
+               vnet_hdr_len = ACCESS_ONCE(q->vnet_hdr_sz);
                if ((len -= vnet_hdr_len) < 0)
                        return -EINVAL;