Sometimes the kernel may not directly call kfree_skb() to drop the sk_buff.
Instead, it "goto drop" and call kfree_skb() at 'drop'. This make it
difficult to track the reason that the sk_buff is dropped.
The commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()") has
introduced the kfree_skb_reason() to help track the reason. However, we may
need to define many reasons for each driver/subsystem.
To avoid introducing so many new reasons, this is to use line number
("__LINE__") to trace where the sk_buff is dropped. As a result, the reason
will be generated automatically.
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Joe Jin <joe.jin@xxxxxxxxxx>
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
include/linux/skbuff.h | 21 ++++-----------------
include/trace/events/skb.h | 35 ++++++-----------------------------
net/core/dev.c | 2 +-
net/core/skbuff.c | 9 ++++-----
net/ipv4/tcp_ipv4.c | 14 +++++++-------
net/ipv4/udp.c | 14 +++++++-------
6 files changed, 29 insertions(+), 66 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 8a636e678902..471268a4a497 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -307,21 +307,8 @@ struct sk_buff_head {
struct sk_buff;
-/* The reason of skb drop, which is used in kfree_skb_reason().
- * en...maybe they should be splited by group?
- *
- * Each item here should also be in 'TRACE_SKB_DROP_REASON', which is
- * used to translate the reason to string.
- */
-enum skb_drop_reason {
- SKB_DROP_REASON_NOT_SPECIFIED,
- SKB_DROP_REASON_NO_SOCKET,
- SKB_DROP_REASON_PKT_TOO_SMALL,
- SKB_DROP_REASON_TCP_CSUM,
- SKB_DROP_REASON_SOCKET_FILTER,
- SKB_DROP_REASON_UDP_CSUM,
- SKB_DROP_REASON_MAX,
-};
+#define SKB_DROP_LINE_NONE 0
+#define SKB_DROP_LINE __LINE__
/* To allow 64K frame to be packed as single skb without frag_list we
* require 64K/PAGE_SIZE pages plus 1 additional page to allow for
@@ -1103,7 +1090,7 @@ static inline bool skb_unref(struct sk_buff *skb)
return true;
}
-void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason);
+void kfree_skb_reason(struct sk_buff *skb, unsigned int line);
/**
* kfree_skb - free an sk_buff with 'NOT_SPECIFIED' reason
@@ -1111,7 +1098,7 @@ void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason);
*/
static inline void kfree_skb(struct sk_buff *skb)
{
- kfree_skb_reason(skb, SKB_DROP_REASON_NOT_SPECIFIED);
+ kfree_skb_reason(skb, SKB_DROP_LINE_NONE);
}
void skb_release_head_state(struct sk_buff *skb);
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index a8a64b97504d..45d1a1757ff1 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -9,56 +9,33 @@
#include <linux/netdevice.h>
#include <linux/tracepoint.h>
-#define TRACE_SKB_DROP_REASON \
- EM(SKB_DROP_REASON_NOT_SPECIFIED, NOT_SPECIFIED) \
- EM(SKB_DROP_REASON_NO_SOCKET, NO_SOCKET) \
- EM(SKB_DROP_REASON_PKT_TOO_SMALL, PKT_TOO_SMALL) \
- EM(SKB_DROP_REASON_TCP_CSUM, TCP_CSUM) \
- EM(SKB_DROP_REASON_SOCKET_FILTER, SOCKET_FILTER) \
- EM(SKB_DROP_REASON_UDP_CSUM, UDP_CSUM) \
- EMe(SKB_DROP_REASON_MAX, MAX)
-
-#undef EM
-#undef EMe
-
-#define EM(a, b) TRACE_DEFINE_ENUM(a);
-#define EMe(a, b) TRACE_DEFINE_ENUM(a);
-
-TRACE_SKB_DROP_REASON
-
-#undef EM
-#undef EMe
-#define EM(a, b) { a, #b },
-#define EMe(a, b) { a, #b }
-
/*
* Tracepoint for free an sk_buff:
*/
TRACE_EVENT(kfree_skb,
TP_PROTO(struct sk_buff *skb, void *location,
- enum skb_drop_reason reason),
+ unsigned int line),
- TP_ARGS(skb, location, reason),
+ TP_ARGS(skb, location, line),
TP_STRUCT__entry(
__field(void *, skbaddr)
__field(void *, location)
__field(unsigned short, protocol)
- __field(enum skb_drop_reason, reason)
+ __field(unsigned int, line)
),
TP_fast_assign(
__entry->skbaddr = skb;
__entry->location = location;
__entry->protocol = ntohs(skb->protocol);
- __entry->reason = reason;
+ __entry->line = line;
),
- TP_printk("skbaddr=%p protocol=%u location=%p reason: %s",
+ TP_printk("skbaddr=%p protocol=%u location=%p line: %u",
__entry->skbaddr, __entry->protocol, __entry->location,
- __print_symbolic(__entry->reason,
- TRACE_SKB_DROP_REASON))
+ __entry->line)
);
TRACE_EVENT(consume_skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index 1baab07820f6..448f390d35d3 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4900,7 +4900,7 @@ static __latent_entropy void net_tx_action(struct softirq_action *h)
trace_consume_skb(skb);
else
trace_kfree_skb(skb, net_tx_action,
- SKB_DROP_REASON_NOT_SPECIFIED);
+ SKB_DROP_LINE);
if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
__kfree_skb(skb);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 0118f0afaa4f..8572c3bce264 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -761,18 +761,17 @@ EXPORT_SYMBOL(__kfree_skb);
/**
* kfree_skb_reason - free an sk_buff with special reason
* @skb: buffer to free
- * @reason: reason why this skb is dropped
+ * @line: the line where this skb is dropped
*
* Drop a reference to the buffer and free it if the usage count has
- * hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
- * tracepoint.
+ * hit zero. Meanwhile, pass the drop line to 'kfree_skb' tracepoint.
*/
-void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
+void kfree_skb_reason(struct sk_buff *skb, unsigned int line)
{
if (!skb_unref(skb))
return;
- trace_kfree_skb(skb, __builtin_return_address(0), reason);
+ trace_kfree_skb(skb, __builtin_return_address(0), line);
__kfree_skb(skb);
}
EXPORT_SYMBOL(kfree_skb_reason);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index fec656f5a39e..f23af94d1186 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1971,10 +1971,10 @@ int tcp_v4_rcv(struct sk_buff *skb)
const struct tcphdr *th;
bool refcounted;
struct sock *sk;
- int drop_reason;
+ unsigned int drop_line;
int ret;
- drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+ drop_line = SKB_DROP_LINE_NONE;
if (skb->pkt_type != PACKET_HOST)
goto discard_it;
@@ -1987,7 +1987,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
th = (const struct tcphdr *)skb->data;
if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) {
- drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
+ drop_line = SKB_DROP_LINE;
goto bad_packet;
}
if (!pskb_may_pull(skb, th->doff * 4))
@@ -2095,7 +2095,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
nf_reset_ct(skb);
if (tcp_filter(sk, skb)) {
- drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
+ drop_line = SKB_DROP_LINE;
goto discard_and_relse;
}
th = (const struct tcphdr *)skb->data;
@@ -2130,7 +2130,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
return ret;
no_tcp_socket:
- drop_reason = SKB_DROP_REASON_NO_SOCKET;
+ drop_line = SKB_DROP_LINE;
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard_it;
@@ -2138,7 +2138,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (tcp_checksum_complete(skb)) {
csum_error:
- drop_reason = SKB_DROP_REASON_TCP_CSUM;
+ drop_line = SKB_DROP_LINE;
trace_tcp_bad_csum(skb);
__TCP_INC_STATS(net, TCP_MIB_CSUMERRORS);
bad_packet:
@@ -2149,7 +2149,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
discard_it:
/* Discard frame. */
- kfree_skb_reason(skb, drop_reason);
+ kfree_skb_reason(skb, drop_line);
return 0;
discard_and_relse:
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 090360939401..f0715d1072d7 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2411,9 +2411,9 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
__be32 saddr, daddr;
struct net *net = dev_net(skb->dev);
bool refcounted;
- int drop_reason;
+ unsigned int drop_line;
- drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+ drop_line = SKB_DROP_LINE_NONE;
/*
* Validate the packet.
@@ -2469,7 +2469,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
if (udp_lib_checksum_complete(skb))
goto csum_error;
- drop_reason = SKB_DROP_REASON_NO_SOCKET;
+ drop_line = SKB_DROP_LINE;
__UDP_INC_STATS(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
@@ -2477,11 +2477,11 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
* Hmm. We got an UDP packet to a port to which we
* don't wanna listen. Ignore it.
*/
- kfree_skb_reason(skb, drop_reason);
+ kfree_skb_reason(skb, drop_line);
return 0;
short_packet:
- drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
+ drop_line = SKB_DROP_LINE;
net_dbg_ratelimited("UDP%s: short packet: From %pI4:%u %d/%d to %pI4:%u\n",
proto == IPPROTO_UDPLITE ? "Lite" : "",
&saddr, ntohs(uh->source),
@@ -2494,7 +2494,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
* RFC1122: OK. Discards the bad packet silently (as far as
* the network is concerned, anyway) as per 4.1.3.4 (MUST).
*/
- drop_reason = SKB_DROP_REASON_UDP_CSUM;
+ drop_line = SKB_DROP_LINE;
net_dbg_ratelimited("UDP%s: bad checksum. From %pI4:%u to %pI4:%u ulen %d\n",
proto == IPPROTO_UDPLITE ? "Lite" : "",
&saddr, ntohs(uh->source), &daddr, ntohs(uh->dest),
@@ -2502,7 +2502,7 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
__UDP_INC_STATS(net, UDP_MIB_CSUMERRORS, proto == IPPROTO_UDPLITE);
drop:
__UDP_INC_STATS(net, UDP_MIB_INERRORS, proto == IPPROTO_UDPLITE);
- kfree_skb_reason(skb, drop_reason);
+ kfree_skb_reason(skb, drop_line);
return 0;
}
--
2.17.1
