Re: [PATCH net-next v5 4/4] gve: Add support for raw addressing in the tx path

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

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Hi David,

I love your patch! Perhaps something to improve:

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

url:    https://github.com/0day-ci/linux/commits/David-Awogbemila/GVE-Raw-Addressing/20201021-021418
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 105faa8742437c28815b2a3eb8314ebc5fd9288c
config: m68k-randconfig-r024-20201030 (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.3.0
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/efba17c94e11da051bdb6b209b740da2a3a0b6be
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review David-Awogbemila/GVE-Raw-Addressing/20201021-021418
        git checkout efba17c94e11da051bdb6b209b740da2a3a0b6be
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 

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

All warnings (new ones prefixed by >>):

   drivers/net/ethernet/google/gve/gve_tx.c: In function 'gve_tx_add_skb_no_copy':
>> drivers/net/ethernet/google/gve/gve_tx.c:511:25: warning: variable 'buf' set but not used [-Wunused-but-set-variable]
     511 |  struct gve_tx_dma_buf *buf;
         |                         ^~~

vim +/buf +511 drivers/net/ethernet/google/gve/gve_tx.c

   501	
   502	static int gve_tx_add_skb_no_copy(struct gve_priv *priv, struct gve_tx_ring *tx,
   503					  struct sk_buff *skb)
   504	{
   505		const struct skb_shared_info *shinfo = skb_shinfo(skb);
   506		int hlen, payload_nfrags, l4_hdr_offset, seg_idx_bias;
   507		union gve_tx_desc *pkt_desc, *seg_desc;
   508		struct gve_tx_buffer_state *info;
   509		bool is_gso = skb_is_gso(skb);
   510		u32 idx = tx->req & tx->mask;
 > 511		struct gve_tx_dma_buf *buf;
   512		int last_mapped = 0;
   513		u64 addr;
   514		u32 len;
   515		int i;
   516	
   517		info = &tx->info[idx];
   518		pkt_desc = &tx->desc[idx];
   519	
   520		l4_hdr_offset = skb_checksum_start_offset(skb);
   521		/* If the skb is gso, then we want only up to the tcp header in the first segment
   522		 * to efficiently replicate on each segment otherwise we want the linear portion
   523		 * of the skb (which will contain the checksum because skb->csum_start and
   524		 * skb->csum_offset are given relative to skb->head) in the first segment.
   525		 */
   526		hlen = is_gso ? l4_hdr_offset + tcp_hdrlen(skb) :
   527				skb_headlen(skb);
   528		len = skb_headlen(skb);
   529	
   530		info->skb =  skb;
   531	
   532		addr = dma_map_single(tx->dev, skb->data, len, DMA_TO_DEVICE);
   533		if (unlikely(dma_mapping_error(tx->dev, addr))) {
   534			priv->dma_mapping_error++;
   535			goto drop;
   536		}
   537		buf = &info->buf;
   538		dma_unmap_len_set(buf, len, len);
   539		dma_unmap_addr_set(buf, dma, addr);
   540	
   541		payload_nfrags = shinfo->nr_frags;
   542		if (hlen < len) {
   543			/* For gso the rest of the linear portion of the skb needs to
   544			 * be in its own descriptor.
   545			 */
   546			payload_nfrags++;
   547			gve_tx_fill_pkt_desc(pkt_desc, skb, is_gso, l4_hdr_offset,
   548					     1 + payload_nfrags, hlen, addr);
   549	
   550			len -= hlen;
   551			addr += hlen;
   552			seg_desc = &tx->desc[(tx->req + 1) & tx->mask];
   553			seg_idx_bias = 2;
   554			gve_tx_fill_seg_desc(seg_desc, skb, is_gso, len, addr);
   555		} else {
   556			seg_idx_bias = 1;
   557			gve_tx_fill_pkt_desc(pkt_desc, skb, is_gso, l4_hdr_offset,
   558					     1 + payload_nfrags, hlen, addr);
   559		}
   560		idx = (tx->req + seg_idx_bias) & tx->mask;
   561	
   562		for (i = 0; i < payload_nfrags - (seg_idx_bias - 1); i++) {
   563			const skb_frag_t *frag = &shinfo->frags[i];
   564	
   565			seg_desc = &tx->desc[idx];
   566			len = skb_frag_size(frag);
   567			addr = skb_frag_dma_map(tx->dev, frag, 0, len, DMA_TO_DEVICE);
   568			if (unlikely(dma_mapping_error(tx->dev, addr))) {
   569				priv->dma_mapping_error++;
   570				goto unmap_drop;
   571			}
   572			buf = &tx->info[idx].buf;
   573			tx->info[idx].skb = NULL;
   574			dma_unmap_len_set(buf, len, len);
   575			dma_unmap_addr_set(buf, dma, addr);
   576	
   577			gve_tx_fill_seg_desc(seg_desc, skb, is_gso, len, addr);
   578			idx = (idx + 1) & tx->mask;
   579		}
   580	
   581		return 1 + payload_nfrags;
   582	
   583	unmap_drop:
   584		i--;
   585		for (last_mapped = i + seg_idx_bias; last_mapped >= 0; last_mapped--) {
   586			idx = (tx->req + last_mapped) & tx->mask;
   587			gve_tx_unmap_buf(tx->dev, &tx->info[idx]);
   588		}
   589	drop:
   590		tx->dropped_pkt++;
   591		return 0;
   592	}
   593	

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

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