Re: [PATCH net-next 2/3] net: use skb_for_each_frag() helper where possible

From: kernel test robot
Date: Fri Apr 09 2021 - 20:30:09 EST

Hi Matteo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url: https://github.com/0day-ci/linux/commits/Matteo-Croce/introduce-skb_for_each_frag/20210410-020828
base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 4438669eb703d1a7416c2b19a8a15b0400b36738
config: um-allmodconfig (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
# https://github.com/0day-ci/linux/commit/9a46b324d3f1ca289db31c0011a6bbfd5ae06918
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Matteo-Croce/introduce-skb_for_each_frag/20210410-020828
git checkout 9a46b324d3f1ca289db31c0011a6bbfd5ae06918
# save the attached .config to linux build tree
make W=1 ARCH=um

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

cc1: warning: arch/um/include/uapi: No such file or directory [-Wmissing-include-dirs]
arch/um/drivers/vector_kern.c: In function 'get_bpf_flash':
arch/um/drivers/vector_kern.c:145:18: warning: ordered comparison of pointer with integer zero [-Wextra]
145 | return (allow > 0);
| ^
arch/um/drivers/vector_kern.c: In function 'prep_skb':
>> arch/um/drivers/vector_kern.c:627:11: warning: variable 'nr_frags' set but not used [-Wunused-but-set-variable]
627 | int err, nr_frags, frag;
| ^~~~~~~~
arch/um/drivers/vector_kern.c: In function 'vector_parse':
arch/um/drivers/vector_kern.c:719:9: warning: variable 'len' set but not used [-Wunused-but-set-variable]
719 | int n, len, err;
| ^~~


vim +/nr_frags +627 arch/um/drivers/vector_kern.c

49da7e64f33e80 Anton Ivanov 2017-11-20 609
49da7e64f33e80 Anton Ivanov 2017-11-20 610 /*
49da7e64f33e80 Anton Ivanov 2017-11-20 611 * We do not use the RX queue as a proper wraparound queue for now
49da7e64f33e80 Anton Ivanov 2017-11-20 612 * This is not necessary because the consumption via netif_rx()
49da7e64f33e80 Anton Ivanov 2017-11-20 613 * happens in-line. While we can try using the return code of
49da7e64f33e80 Anton Ivanov 2017-11-20 614 * netif_rx() for flow control there are no drivers doing this today.
49da7e64f33e80 Anton Ivanov 2017-11-20 615 * For this RX specific use we ignore the tail/head locks and
49da7e64f33e80 Anton Ivanov 2017-11-20 616 * just read into a prepared queue filled with skbuffs.
49da7e64f33e80 Anton Ivanov 2017-11-20 617 */
49da7e64f33e80 Anton Ivanov 2017-11-20 618
49da7e64f33e80 Anton Ivanov 2017-11-20 619 static struct sk_buff *prep_skb(
49da7e64f33e80 Anton Ivanov 2017-11-20 620 struct vector_private *vp,
49da7e64f33e80 Anton Ivanov 2017-11-20 621 struct user_msghdr *msg)
49da7e64f33e80 Anton Ivanov 2017-11-20 622 {
49da7e64f33e80 Anton Ivanov 2017-11-20 623 int linear = vp->max_packet + vp->headroom + SAFETY_MARGIN;
49da7e64f33e80 Anton Ivanov 2017-11-20 624 struct sk_buff *result;
49da7e64f33e80 Anton Ivanov 2017-11-20 625 int iov_index = 0, len;
49da7e64f33e80 Anton Ivanov 2017-11-20 626 struct iovec *iov = msg->msg_iov;
49da7e64f33e80 Anton Ivanov 2017-11-20 @627 int err, nr_frags, frag;
49da7e64f33e80 Anton Ivanov 2017-11-20 628 skb_frag_t *skb_frag;
49da7e64f33e80 Anton Ivanov 2017-11-20 629
49da7e64f33e80 Anton Ivanov 2017-11-20 630 if (vp->req_size <= linear)
49da7e64f33e80 Anton Ivanov 2017-11-20 631 len = linear;
49da7e64f33e80 Anton Ivanov 2017-11-20 632 else
49da7e64f33e80 Anton Ivanov 2017-11-20 633 len = vp->req_size;
49da7e64f33e80 Anton Ivanov 2017-11-20 634 result = alloc_skb_with_frags(
49da7e64f33e80 Anton Ivanov 2017-11-20 635 linear,
49da7e64f33e80 Anton Ivanov 2017-11-20 636 len - vp->max_packet,
49da7e64f33e80 Anton Ivanov 2017-11-20 637 3,
49da7e64f33e80 Anton Ivanov 2017-11-20 638 &err,
49da7e64f33e80 Anton Ivanov 2017-11-20 639 GFP_ATOMIC
49da7e64f33e80 Anton Ivanov 2017-11-20 640 );
49da7e64f33e80 Anton Ivanov 2017-11-20 641 if (vp->header_size > 0)
49da7e64f33e80 Anton Ivanov 2017-11-20 642 iov_index++;
49da7e64f33e80 Anton Ivanov 2017-11-20 643 if (result == NULL) {
49da7e64f33e80 Anton Ivanov 2017-11-20 644 iov[iov_index].iov_base = NULL;
49da7e64f33e80 Anton Ivanov 2017-11-20 645 iov[iov_index].iov_len = 0;
49da7e64f33e80 Anton Ivanov 2017-11-20 646 goto done;
49da7e64f33e80 Anton Ivanov 2017-11-20 647 }
49da7e64f33e80 Anton Ivanov 2017-11-20 648 skb_reserve(result, vp->headroom);
49da7e64f33e80 Anton Ivanov 2017-11-20 649 result->dev = vp->dev;
49da7e64f33e80 Anton Ivanov 2017-11-20 650 skb_put(result, vp->max_packet);
49da7e64f33e80 Anton Ivanov 2017-11-20 651 result->data_len = len - vp->max_packet;
49da7e64f33e80 Anton Ivanov 2017-11-20 652 result->len += len - vp->max_packet;
49da7e64f33e80 Anton Ivanov 2017-11-20 653 skb_reset_mac_header(result);
49da7e64f33e80 Anton Ivanov 2017-11-20 654 result->ip_summed = CHECKSUM_NONE;
49da7e64f33e80 Anton Ivanov 2017-11-20 655 iov[iov_index].iov_base = result->data;
49da7e64f33e80 Anton Ivanov 2017-11-20 656 iov[iov_index].iov_len = vp->max_packet;
49da7e64f33e80 Anton Ivanov 2017-11-20 657 iov_index++;
49da7e64f33e80 Anton Ivanov 2017-11-20 658
49da7e64f33e80 Anton Ivanov 2017-11-20 659 nr_frags = skb_shinfo(result)->nr_frags;
9a46b324d3f1ca Matteo Croce 2021-04-09 660 skb_for_each_frag(result, frag) {
49da7e64f33e80 Anton Ivanov 2017-11-20 661 skb_frag = &skb_shinfo(result)->frags[frag];
49da7e64f33e80 Anton Ivanov 2017-11-20 662 iov[iov_index].iov_base = skb_frag_address_safe(skb_frag);
49da7e64f33e80 Anton Ivanov 2017-11-20 663 if (iov[iov_index].iov_base != NULL)
49da7e64f33e80 Anton Ivanov 2017-11-20 664 iov[iov_index].iov_len = skb_frag_size(skb_frag);
49da7e64f33e80 Anton Ivanov 2017-11-20 665 else
49da7e64f33e80 Anton Ivanov 2017-11-20 666 iov[iov_index].iov_len = 0;
49da7e64f33e80 Anton Ivanov 2017-11-20 667 iov_index++;
49da7e64f33e80 Anton Ivanov 2017-11-20 668 }
49da7e64f33e80 Anton Ivanov 2017-11-20 669 done:
49da7e64f33e80 Anton Ivanov 2017-11-20 670 msg->msg_iovlen = iov_index;
49da7e64f33e80 Anton Ivanov 2017-11-20 671 return result;
49da7e64f33e80 Anton Ivanov 2017-11-20 672 }
49da7e64f33e80 Anton Ivanov 2017-11-20 673

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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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