Commit 74212f20 authored by Akihiko Odaki's avatar Akihiko Odaki Committed by Jakub Kicinski
Browse files

tap: Keep hdr_len in tap_get_user() 



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

Signed-off-by: default avatarAkihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250207-tun-v6-6-fb49cf8b103e@daynix.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 1d41e2fa

drivers/net/tap.c

+10 −18
Original line number Diff line number Diff line
@@ -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;
@@ -663,13 +664,13 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 
		if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))

			goto err;

		iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));

		if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&

		     tap16_to_cpu(q, vnet_hdr.csum_start) +

		     tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >

			     tap16_to_cpu(q, vnet_hdr.hdr_len))

			vnet_hdr.hdr_len = cpu_to_tap16(q,

				 tap16_to_cpu(q, vnet_hdr.csum_start) +

				 tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);

		hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len);

		if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {

			hdr_len = max(tap16_to_cpu(q, vnet_hdr.csum_start) +

				      tap16_to_cpu(q, vnet_hdr.csum_offset) + 2,

				      hdr_len);

			vnet_hdr.hdr_len = cpu_to_tap16(q, hdr_len);

		}

		err = -EINVAL;

		if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)

			goto err;
@@ -682,12 +683,7 @@ 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 = ETH_HLEN;

		copylen = clamp(hdr_len ?: GOODCOPY_LEN, ETH_HLEN, good_linear);

		linear = copylen;

		i = *from;

		iov_iter_advance(&i, copylen);
@@ -697,11 +693,7 @@ 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 = clamp(hdr_len, ETH_HLEN, good_linear);

	}



	skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,