[PATCH net-next v4 8/9] tap: Keep hdr_len in tap_get_user()

[Akihiko Odaki]

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

Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
---
 drivers/net/tap.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 061c2f27dfc83f5e6d0bea4da0e845cc429b1fd8..7ee2e9ee2a89fd539b087496b92d2f6198266f44 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 	int err;
 	struct virtio_net_hdr vnet_hdr = { 0 };
 	int vnet_hdr_len = 0;
+	int hdr_len = 0;
 	int copylen = 0;
 	int depth;
 	bool zerocopy = false;
@@ -672,6 +673,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 		err = -EINVAL;
 		if (tap16_to_cpu(q, vnet_hdr.hdr_len) > iov_iter_count(from))
 			goto err;
+		hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len);
 	}
 
 	len = iov_iter_count(from);
@@ -683,11 +685,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 	if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
 		struct iov_iter i;
 
-		copylen = vnet_hdr.hdr_len ?
-			tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
-		if (copylen > good_linear)
-			copylen = good_linear;
-		else if (copylen < ETH_HLEN)
+		copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear);
+		if (copylen < ETH_HLEN)
 			copylen = ETH_HLEN;
 		linear = copylen;
 		i = *from;
@@ -698,11 +697,9 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
 
 	if (!zerocopy) {
 		copylen = len;
-		linear = tap16_to_cpu(q, vnet_hdr.hdr_len);
-		if (linear > good_linear)
-			linear = good_linear;
-		else if (linear < ETH_HLEN)
-			linear = ETH_HLEN;
+		linear = min(hdr_len, good_linear);
+		if (copylen < ETH_HLEN)
+			copylen = ETH_HLEN;
 	}
 
 	skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,

-- 
2.47.1