Re: [RFC PATCH 2/4] drivers/net/virtio_net: Changed mergeable buffer length calculation.

[kernel test robot <lkp@intel.com>]

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Hi Andrew,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on mst-vhost/linux-next]
[also build test ERROR on net-next/master net/master linus/master v5.15-rc7 next-20211029]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Andrew-Melnychenko/Added-RSS-support/20211031-130048
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: riscv-allyesconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 11.2.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/ca643e21484393b5386b7b86542c3ebb37445a70
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Andrew-Melnychenko/Added-RSS-support/20211031-130048
        git checkout ca643e21484393b5386b7b86542c3ebb37445a70
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=riscv SHELL=/bin/bash drivers/

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

Note: the linux-review/Andrew-Melnychenko/Added-RSS-support/20211031-130048 HEAD 385fe5b07bf0ded4667d57d48eacf27e3d4e3733 builds fine.
      It only hurts bisectability.

All errors (new ones prefixed by >>):

   drivers/net/virtio_net.c: In function 'page_to_skb':
>> drivers/net/virtio_net.c:396:15: error: 'struct virtnet_info' has no member named 'has_rss_hash_report'
     396 |         if (vi->has_rss_hash_report)
         |               ^~


vim +396 drivers/net/virtio_net.c

   376	
   377	/* Called from bottom half context */
   378	static struct sk_buff *page_to_skb(struct virtnet_info *vi,
   379					   struct receive_queue *rq,
   380					   struct page *page, unsigned int offset,
   381					   unsigned int len, unsigned int truesize,
   382					   bool hdr_valid, unsigned int metasize,
   383					   unsigned int headroom)
   384	{
   385		struct sk_buff *skb;
   386		struct virtio_net_hdr_mrg_rxbuf *hdr;
   387		unsigned int copy, hdr_len, hdr_padded_len;
   388		struct page *page_to_free = NULL;
   389		int tailroom, shinfo_size;
   390		char *p, *hdr_p, *buf;
   391	
   392		p = page_address(page) + offset;
   393		hdr_p = p;
   394	
   395		hdr_len = vi->hdr_len;
 > 396		if (vi->has_rss_hash_report)
   397			hdr_padded_len = sizeof(struct virtio_net_hdr_v1_hash);
   398		else if (vi->mergeable_rx_bufs)
   399			hdr_padded_len = sizeof(*hdr);
   400		else
   401			hdr_padded_len = sizeof(struct padded_vnet_hdr);
   402	
   403		/* If headroom is not 0, there is an offset between the beginning of the
   404		 * data and the allocated space, otherwise the data and the allocated
   405		 * space are aligned.
   406		 *
   407		 * Buffers with headroom use PAGE_SIZE as alloc size, see
   408		 * add_recvbuf_mergeable() + get_mergeable_buf_len()
   409		 */
   410		truesize = headroom ? PAGE_SIZE : truesize;
   411		tailroom = truesize - headroom;
   412		buf = p - headroom;
   413	
   414		len -= hdr_len;
   415		offset += hdr_padded_len;
   416		p += hdr_padded_len;
   417		tailroom -= hdr_padded_len + len;
   418	
   419		shinfo_size = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
   420	
   421		/* copy small packet so we can reuse these pages */
   422		if (!NET_IP_ALIGN && len > GOOD_COPY_LEN && tailroom >= shinfo_size) {
   423			skb = build_skb(buf, truesize);
   424			if (unlikely(!skb))
   425				return NULL;
   426	
   427			skb_reserve(skb, p - buf);
   428			skb_put(skb, len);
   429	
   430			page = (struct page *)page->private;
   431			if (page)
   432				give_pages(rq, page);
   433			goto ok;
   434		}
   435	
   436		/* copy small packet so we can reuse these pages for small data */
   437		skb = napi_alloc_skb(&rq->napi, GOOD_COPY_LEN);
   438		if (unlikely(!skb))
   439			return NULL;
   440	
   441		/* Copy all frame if it fits skb->head, otherwise
   442		 * we let virtio_net_hdr_to_skb() and GRO pull headers as needed.
   443		 */
   444		if (len <= skb_tailroom(skb))
   445			copy = len;
   446		else
   447			copy = ETH_HLEN + metasize;
   448		skb_put_data(skb, p, copy);
   449	
   450		len -= copy;
   451		offset += copy;
   452	
   453		if (vi->mergeable_rx_bufs) {
   454			if (len)
   455				skb_add_rx_frag(skb, 0, page, offset, len, truesize);
   456			else
   457				page_to_free = page;
   458			goto ok;
   459		}
   460	
   461		/*
   462		 * Verify that we can indeed put this data into a skb.
   463		 * This is here to handle cases when the device erroneously
   464		 * tries to receive more than is possible. This is usually
   465		 * the case of a broken device.
   466		 */
   467		if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) {
   468			net_dbg_ratelimited("%s: too much data\n", skb->dev->name);
   469			dev_kfree_skb(skb);
   470			return NULL;
   471		}
   472		BUG_ON(offset >= PAGE_SIZE);
   473		while (len) {
   474			unsigned int frag_size = min((unsigned)PAGE_SIZE - offset, len);
   475			skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, offset,
   476					frag_size, truesize);
   477			len -= frag_size;
   478			page = (struct page *)page->private;
   479			offset = 0;
   480		}
   481	
   482		if (page)
   483			give_pages(rq, page);
   484	
   485	ok:
   486		/* hdr_valid means no XDP, so we can copy the vnet header */
   487		if (hdr_valid) {
   488			hdr = skb_vnet_hdr(skb);
   489			memcpy(hdr, hdr_p, hdr_len);
   490		}
   491		if (page_to_free)
   492			put_page(page_to_free);
   493	
   494		if (metasize) {
   495			__skb_pull(skb, metasize);
   496			skb_metadata_set(skb, metasize);
   497		}
   498	
   499		return skb;
   500	}
   501	

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

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