[PATCH net v3 3/9] tun: Keep hdr_len in tun_get_user()

[Akihiko Odaki]

hdr_len is repeatedly used so keep it in a local variable.

Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
---
 drivers/net/tun.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index bd272b4736fb..ec56ac865848 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1746,6 +1746,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
        struct virtio_net_hdr gso = { 0 };
        int good_linear;
        int copylen;
+       int hdr_len = 0;
        bool zerocopy = false;
        int err;
        u32 rxhash = 0;
@@ -1776,6 +1777,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
 
                if (tun16_to_cpu(tun, gso.hdr_len) > iov_iter_count(from))
                        return -EINVAL;
+               hdr_len = tun16_to_cpu(tun, gso.hdr_len);
                iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
        }
 
@@ -1783,8 +1785,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
 
        if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
                align += NET_IP_ALIGN;
-               if (unlikely(len < ETH_HLEN ||
-                            (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < 
ETH_HLEN)))
+               if (unlikely(len < ETH_HLEN || (hdr_len && hdr_len < ETH_HLEN)))
                        return -EINVAL;
        }
 
@@ -1797,9 +1798,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
                 * enough room for skb expand head in case it is used.
                 * The rest of the buffer is mapped from userspace.
                 */
-               copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : 
GOODCOPY_LEN;
-               if (copylen > good_linear)
-                       copylen = good_linear;
+               copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear);
                linear = copylen;
                iov_iter_advance(&i, copylen);
                if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
@@ -1820,10 +1819,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, 
struct tun_file *tfile,
        } else {
                if (!zerocopy) {
                        copylen = len;
-                       if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
-                               linear = good_linear;
-                       else
-                               linear = tun16_to_cpu(tun, gso.hdr_len);
+                       linear = min(hdr_len, good_linear);
                }
 
                if (frags) {

-- 
2.47.1