On 3/20/18 5:44 PM, Eric Dumazet wrote:
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 <y...@fb.com>
---
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 ?
Thanks, Eric. This is purely due to my 'laziness' to make it work as I
know that skb_segment does not really enforce this. I will address
all of your comments in the next revision.
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;
}
