netdev - [Patch net-next 2/2] net: dump whole skb data in netdev_rx_csum

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Message-Id: <20181121021309.6595-2-xiyou.wangcong@gmail.com>
Date:   Tue, 20 Nov 2018 18:13:09 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>
Subject: [Patch net-next 2/2] net: dump whole skb data in netdev_rx_csum_fault()

Currently, we only dump a few selected skb fields in
netdev_rx_csum_fault(). It is not suffient for debugging checksum
fault. This patch introduces skb_dump() which dumps skb mac header,
network header and its whole skb->data too.

Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: David Miller <davem@...emloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 include/linux/skbuff.h |  5 +++++
 net/core/dev.c         |  6 +-----
 net/core/skbuff.c      | 49 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index afddb5c17ce5..844c0a7ff52f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4218,5 +4218,10 @@ static inline __wsum lco_csum(struct sk_buff *skb)
 	return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
 }
 
+#ifdef CONFIG_BUG
+void skb_dump(const char *level, const struct sk_buff *skb, bool dump_header,
+	      bool dump_mac_header, bool dump_network_header);
+#endif
+
 #endif	/* __KERNEL__ */
 #endif	/* _LINUX_SKBUFF_H */
diff --git a/net/core/dev.c b/net/core/dev.c
index f2bfd2eda7b2..dc54c89fb4b1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3097,11 +3097,7 @@ void netdev_rx_csum_fault(struct net_device *dev, struct sk_buff *skb)
 		pr_err("%s: hw csum failure\n", dev ? dev->name : "<unknown>");
 		if (dev)
 			pr_err("dev features: %pNF\n", &dev->features);
-		pr_err("skb len=%u data_len=%u pkt_type=%u gso_size=%u gso_type=%u nr_frags=%u ip_summed=%u csum=%x csum_complete_sw=%d csum_valid=%d csum_level=%u\n",
-		       skb->len, skb->data_len, skb->pkt_type,
-		       skb_shinfo(skb)->gso_size, skb_shinfo(skb)->gso_type,
-		       skb_shinfo(skb)->nr_frags, skb->ip_summed, skb->csum,
-		       skb->csum_complete_sw, skb->csum_valid, skb->csum_level);
+		skb_dump(KERN_ERR, skb, true, true, true);
 		dump_stack();
 	}
 }
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b6ba923e7dc7..21aaef3f6a4a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5555,3 +5555,52 @@ void skb_condense(struct sk_buff *skb)
 	 */
 	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
 }
+
+#ifdef CONFIG_BUG
+void skb_dump(const char *level, const struct sk_buff *skb, bool dump_header,
+	      bool dump_mac_header, bool dump_network_header)
+{
+	struct sk_buff *frag_iter;
+	int i;
+
+	if (dump_header)
+		printk("%sskb len=%u data_len=%u pkt_type=%u gso_size=%u gso_type=%u nr_frags=%u ip_summed=%u csum=%x csum_complete_sw=%d csum_valid=%d csum_level=%u\n",
+		       level, skb->len, skb->data_len, skb->pkt_type,
+		       skb_shinfo(skb)->gso_size, skb_shinfo(skb)->gso_type,
+		       skb_shinfo(skb)->nr_frags, skb->ip_summed, skb->csum,
+		       skb->csum_complete_sw, skb->csum_valid, skb->csum_level);
+
+	if (dump_mac_header && skb_mac_header_was_set(skb))
+		print_hex_dump(level, "mac header: ", DUMP_PREFIX_OFFSET, 16, 1,
+			       skb_mac_header(skb), skb_mac_header_len(skb),
+			       false);
+
+	if (dump_network_header && skb_network_header_was_set(skb))
+		print_hex_dump(level, "network header: ", DUMP_PREFIX_OFFSET,
+			       16, 1, skb_network_header(skb),
+			       skb_network_header_len(skb), false);
+
+	print_hex_dump(level, "skb data: ", DUMP_PREFIX_OFFSET, 16, 1,
+		       skb->data, skb->len, false);
+
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+		u32 p_off, p_len, copied;
+		struct page *p;
+		u8 *vaddr;
+
+		skb_frag_foreach_page(frag, frag->page_offset, skb_frag_size(frag),
+				      p, p_off, p_len, copied) {
+			vaddr = kmap_atomic(p);
+			print_hex_dump(level, "skb frag: ", DUMP_PREFIX_OFFSET,
+				       16, 1, vaddr + p_off, p_len, false);
+			kunmap_atomic(vaddr);
+		}
+	}
+
+	if (skb_has_frag_list(skb))
+		printk("%sskb frags list:\n", level);
+	skb_walk_frags(skb, frag_iter)
+		skb_dump(level, frag_iter, false, false, false);
+}
+#endif
-- 
2.19.1