On 2025/02/06 6:21, Willem de Bruijn wrote:
Akihiko Odaki wrote:
hdr_len is repeatedly used so keep it in a local variable.
Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
@@ -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);
I introduced the min() usage as it now neatly fits in a line, but I
found even clamp() fits so I'll use it in the next version:
copylen = clamp(hdr_len ?: GOODCOPY_LEN, ETH_HLEN, good_linear);
Please tell me if you prefer hdr_len ?: GOODCOPY_LEN in a separate line:
copylen = hdr_len ?: GOODCOPY_LEN;
copylen = clamp(copylen, ETH_HLEN, good_linear);
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
I realized I mistakenly replaced linear with copylen here. Using clamp()
will remove redundant variable references and fix the bug.
