From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:42037 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751018AbeCUAoK (ORCPT ); Tue, 20 Mar 2018 20:44:10 -0400 Received: by mail-pg0-f67.google.com with SMTP id f10so1161058pgs.9 for ; Tue, 20 Mar 2018 17:44:10 -0700 (PDT) Subject: Re: [PATCH net-next v3 2/2] net: bpf: add a test for skb_segment in test_bpf module To: Yonghong Song , edumazet@google.com, ast@fb.com, daniel@iogearbox.net, diptanu@fb.com, netdev@vger.kernel.org, alexander.duyck@gmail.com Cc: kernel-team@fb.com References: <20180320232156.3455738-1-yhs@fb.com> <20180320232156.3455738-3-yhs@fb.com> From: Eric Dumazet Message-ID: <890b597a-85b6-a3fc-3419-8cace6d0f2b7@gmail.com> Date: Tue, 20 Mar 2018 17:44:07 -0700 MIME-Version: 1.0 In-Reply-To: <20180320232156.3455738-3-yhs@fb.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org List-ID: On 03/20/2018 04:21 PM, Yonghong Song wrote: > Without the previous commit, > "modprobe test_bpf" will have the following errors: > ... > [ 98.149165] ------------[ cut here ]------------ > [ 98.159362] kernel BUG at net/core/skbuff.c:3667! > [ 98.169756] invalid opcode: 0000 [#1] SMP PTI > [ 98.179370] Modules linked in: > [ 98.179371] test_bpf(+) > ... > which triggers the bug the previous commit intends to fix. > > The skbs are constructed to mimic what mlx5 may generate. > The packet size/header may not mimic real cases in production. But > the processing flow is similar. > > Signed-off-by: Yonghong Song > --- > lib/test_bpf.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 70 insertions(+), 1 deletion(-) > > diff --git a/lib/test_bpf.c b/lib/test_bpf.c > index 2efb213..045d7d3 100644 > --- a/lib/test_bpf.c > +++ b/lib/test_bpf.c > @@ -6574,6 +6574,72 @@ static bool exclude_test(int test_id) > return test_id < test_range[0] || test_id > test_range[1]; > } > > +static struct sk_buff *build_test_skb(void *page) > +{ > + u32 headroom = NET_SKB_PAD + NET_IP_ALIGN + ETH_HLEN; > + struct sk_buff *skb[2]; > + int i, data_size = 8; > + > + for (i = 0; i < 2; i++) { > + /* this will set skb[i]->head_frag */ > + skb[i] = build_skb(page, headroom); > + if (!skb[i]) > + return NULL; You are using the same virtual address (page) for both skb ? So we have 2 skbs having skb->head pointing to the same location ? This is illegal. Please use instead : skb = dev_alloc_skb(headroom + data_size) > + > + skb_reserve(skb[i], headroom); > + skb_put(skb[i], data_size); > + skb[i]->protocol = htons(ETH_P_IP); > + skb_reset_network_header(skb[i]); > + skb_set_mac_header(skb[i], -ETH_HLEN); > + > + skb_add_rx_frag(skb[i], skb_shinfo(skb[i])->nr_frags, 0 ? > + page, 0, 64, 64); get_page(page) ? > + // skb: skb_headlen(skb[i]): 8, skb[i]->head_frag = 1 > + } > + > + /* setup shinfo */ > + skb_shinfo(skb[0])->gso_size = 1448; > + skb_shinfo(skb[0])->gso_type = SKB_GSO_TCPV4; > + skb_shinfo(skb[0])->gso_type |= SKB_GSO_DODGY; > + skb_shinfo(skb[0])->gso_segs = 0; > + skb_shinfo(skb[0])->frag_list = skb[1]; > + > + /* adjust skb[0]'s len */ > + skb[0]->len += skb[1]->len; > + skb[0]->data_len += skb[1]->data_len; > + skb[0]->truesize += skb[1]->truesize; > + > + return skb[0]; > +} > + > +static __init int test_skb_segment(void) > +{ > + netdev_features_t features; > + struct sk_buff *skb; > + void *page; > + int ret = -1; > + > + page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); > + if (!page) { > + pr_info("%s: failed to get_free_page!", __func__); > + return ret; > + } > + > + features = NETIF_F_SG | NETIF_F_GSO_PARTIAL | NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM; > + features |= NETIF_F_RXCSUM; > + skb = build_test_skb(page); > + if (!skb) { > + pr_info("%s: failed to build_test_skb", __func__); > + } else if (skb_segment(skb, features)) { > + ret = 0; > + pr_info("%s: success in skb_segment!", __func__); > + } else { > + pr_info("%s: failed in skb_segment!", __func__); > + } > + free_page((unsigned long)page); Where are the skbs freed ? > + return ret; > +} > + > static __init int test_bpf(void) > { > int i, err_cnt = 0, pass_cnt = 0; > @@ -6632,8 +6698,11 @@ static int __init test_bpf_init(void) > return ret; > > ret = test_bpf(); > - > destroy_bpf_tests(); > + if (ret) > + return ret; > + > + ret = test_skb_segment(); > return ret; > } > >