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net: bpf: add a test for skb_segment in test_bpf module

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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 <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yonghong Song 2018-03-21 16:31:04 -07:00 committed by David S. Miller
parent 13acc94eff
commit 76db8087c4
1 changed files with 91 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

91
lib/test_bpf.c
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@ -6574,6 +6574,93 @@ static bool exclude_test(int test_id)
return test_id < test_range[0] || test_id > test_range[1]; return test_id < test_range[0] || test_id > test_range[1];
} }
static __init struct sk_buff *build_test_skb(void)
{
u32 headroom = NET_SKB_PAD + NET_IP_ALIGN + ETH_HLEN;
struct sk_buff *skb[2];
struct page *page[2];
int i, data_size = 8;
for (i = 0; i < 2; i++) {
page[i] = alloc_page(GFP_KERNEL);
if (!page[i]) {
if (i == 0)
goto err_page0;
else
goto err_page1;
}
/* this will set skb[i]->head_frag */
skb[i] = dev_alloc_skb(headroom + data_size);
if (!skb[i]) {
if (i == 0)
goto err_skb0;
else
goto err_skb1;
}
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], 0, page[i], 0, 64, 64);
// 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];
err_skb1:
__free_page(page[1]);
err_page1:
kfree_skb(skb[0]);
err_skb0:
__free_page(page[0]);
err_page0:
return NULL;
}
static __init int test_skb_segment(void)
{
netdev_features_t features;
struct sk_buff *skb, *segs;
int ret = -1;
features = NETIF_F_SG | NETIF_F_GSO_PARTIAL | NETIF_F_IP_CSUM |
NETIF_F_IPV6_CSUM;
features |= NETIF_F_RXCSUM;
skb = build_test_skb();
if (!skb) {
pr_info("%s: failed to build_test_skb", __func__);
goto done;
}
segs = skb_segment(skb, features);
if (segs) {
kfree_skb_list(segs);
ret = 0;
pr_info("%s: success in skb_segment!", __func__);
} else {
pr_info("%s: failed in skb_segment!", __func__);
}
kfree_skb(skb);
done:
return ret;
}
static __init int test_bpf(void) static __init int test_bpf(void)
{ {
int i, err_cnt = 0, pass_cnt = 0; int i, err_cnt = 0, pass_cnt = 0;
@ -6632,9 +6719,11 @@ static int __init test_bpf_init(void)
return ret; return ret;
ret = test_bpf(); ret = test_bpf();
destroy_bpf_tests(); destroy_bpf_tests();
if (ret)
return ret; return ret;
return test_skb_segment();
} }
static void __exit test_bpf_exit(void) static void __exit test_bpf_exit(void)