Re: [PATCH net-next v5 6/7] tap: Keep hdr_len in tap_get_user()
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2025-02-05 21:21:54
Also in:
kvm, linux-doc, linux-kselftest, lkml, virtualization
Akihiko Odaki wrote:
hdr_len is repeatedly used so keep it in a local variable. Signed-off-by: Akihiko Odaki <redacted>
quoted hunk ↗ jump to hunk
@@ -682,11 +683,8 @@ 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;
I forgot earlier: this can also use single line statement
copylen = max(copylen, ETH_HLEN);
And perhaps easiest to follow is
copylen = hdr_len ?: GOODCOPY_LEN;
copylen = min(copylen, good_linear);
copylen = max(copylen, ETH_HLEN);
quoted hunk ↗ jump to hunk
linear = copylen; i = *from;@@ -697,11 +695,9 @@ 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;
Same