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

Commit Message

Akihiko Odaki Jan. 16, 2025, 8:08 a.m. UTC

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

Signed-off-by: Akihiko Odaki <[e-mail]>
---
 drivers/net/tun.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

Patch

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) {