tun: fallback if skb_alloc() fails on big packets

[linux-2.6-omap-h63xx.git] / drivers / net / tun.c

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 95931a5a98838d5c21af7e7b3de414c0140af466..6daea0c91862ecddc2110712c8e62381e1e9639c 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -358,6 +358,66 @@ static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
        return mask;
 }
 
+/* prepad is the amount to reserve at front.  len is length after that.
+ * linear is a hint as to how much to copy (usually headers). */
+static struct sk_buff *tun_alloc_skb(size_t prepad, size_t len, size_t linear,
+                                    gfp_t gfp)
+{
+       struct sk_buff *skb;
+       unsigned int i;
+
+       skb = alloc_skb(prepad + len, gfp|__GFP_NOWARN);
+       if (skb) {
+               skb_reserve(skb, prepad);
+               skb_put(skb, len);
+               return skb;
+       }
+
+       /* Under a page?  Don't bother with paged skb. */
+       if (prepad + len < PAGE_SIZE)
+               return NULL;
+
+       /* Start with a normal skb, and add pages. */
+       skb = alloc_skb(prepad + linear, gfp);
+       if (!skb)
+               return NULL;
+
+       skb_reserve(skb, prepad);
+       skb_put(skb, linear);
+
+       len -= linear;
+
+       for (i = 0; i < MAX_SKB_FRAGS; i++) {
+               skb_frag_t *f = &skb_shinfo(skb)->frags[i];
+
+               f->page = alloc_page(gfp|__GFP_ZERO);
+               if (!f->page)
+                       break;
+
+               f->page_offset = 0;
+               f->size = PAGE_SIZE;
+
+               skb->data_len += PAGE_SIZE;
+               skb->len += PAGE_SIZE;
+               skb->truesize += PAGE_SIZE;
+               skb_shinfo(skb)->nr_frags++;
+
+               if (len < PAGE_SIZE) {
+                       len = 0;
+                       break;
+               }
+               len -= PAGE_SIZE;
+       }
+
+       /* Too large, or alloc fail? */
+       if (unlikely(len)) {
+               kfree_skb(skb);
+               skb = NULL;
+       }
+
+       return skb;
+}
+
 /* Get packet from user space buffer */
 static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, size_t count)
 {
@@ -391,14 +451,12 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
                        return -EINVAL;
        }
 
-       if (!(skb = alloc_skb(len + align, GFP_KERNEL))) {
+       if (!(skb = tun_alloc_skb(align, len, gso.hdr_len, GFP_KERNEL))) {
                tun->dev->stats.rx_dropped++;
                return -ENOMEM;
        }
 
-       if (align)
-               skb_reserve(skb, align);
-       if (memcpy_fromiovec(skb_put(skb, len), iv, len)) {
+       if (skb_copy_datagram_from_iovec(skb, 0, iv, len)) {
                tun->dev->stats.rx_dropped++;
                kfree_skb(skb);
                return -EFAULT;