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Date: Thu, 3 Feb 2022 07:37:29 -0800
From: Dongli Zhang <dongli.zhang@...cle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, rostedt@...dmis.org,
mingo@...hat.com, davem@...emloft.net, kuba@...nel.org,
edumazet@...gle.com, yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
imagedong@...cent.com, joao.m.martins@...cle.com,
joe.jin@...cle.com
Subject: [PATCH RFC 2/4] net: skb: add function name as part of reason
In addition to the line number ("__LINE__"), this is to make the
function name ("__func__", which is the caller of kfree_skb_reason())
as part of reason.
The (function, line) combination is able to uniquely represent where the
sk_buff is dropped.
The existing trace_kfree_skb() is able to trace the 'location'. While it
is fine to either echo 'stacktrace' to the trigger, or trace at
userspace via ebpf, the TP_printk will only print %p.
With the function name, the TP_printk will tell the function and the
line number that the sk_buff is dropped.
Cc: Joao Martins <joao.m.martins@...cle.com>
Cc: Joe Jin <joe.jin@...cle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@...cle.com>
---
include/linux/skbuff.h | 7 +++++--
include/trace/events/skb.h | 10 ++++++----
net/core/dev.c | 1 +
net/core/skbuff.c | 9 ++++++---
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv4/udp.c | 4 ++--
6 files changed, 21 insertions(+), 12 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 471268a4a497..10bcbe4f690f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -309,6 +309,8 @@ struct sk_buff;
#define SKB_DROP_LINE_NONE 0
#define SKB_DROP_LINE __LINE__
+#define SKB_DROP_FUNC_NONE "none"
+#define SKB_DROP_FUNC __func__
/* 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
@@ -1090,7 +1092,8 @@ static inline bool skb_unref(struct sk_buff *skb)
return true;
}
-void kfree_skb_reason(struct sk_buff *skb, unsigned int line);
+void kfree_skb_reason(struct sk_buff *skb, const char *func,
+ unsigned int line);
/**
* kfree_skb - free an sk_buff with 'NOT_SPECIFIED' reason
@@ -1098,7 +1101,7 @@ void kfree_skb_reason(struct sk_buff *skb, unsigned int line);
*/
static inline void kfree_skb(struct sk_buff *skb)
{
- kfree_skb_reason(skb, SKB_DROP_LINE_NONE);
+ kfree_skb_reason(skb, SKB_DROP_FUNC_NONE, 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 45d1a1757ff1..b63bf724809e 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -15,14 +15,15 @@
TRACE_EVENT(kfree_skb,
TP_PROTO(struct sk_buff *skb, void *location,
- unsigned int line),
+ const char *function, unsigned int line),
- TP_ARGS(skb, location, line),
+ TP_ARGS(skb, location, function, line),
TP_STRUCT__entry(
__field(void *, skbaddr)
__field(void *, location)
__field(unsigned short, protocol)
+ __string(function, function)
__field(unsigned int, line)
),
@@ -30,12 +31,13 @@ TRACE_EVENT(kfree_skb,
__entry->skbaddr = skb;
__entry->location = location;
__entry->protocol = ntohs(skb->protocol);
+ __assign_str(function, function);
__entry->line = line;
),
- TP_printk("skbaddr=%p protocol=%u location=%p line: %u",
+ TP_printk("skbaddr=%p protocol=%u location=%p function=%s line=%u",
__entry->skbaddr, __entry->protocol, __entry->location,
- __entry->line)
+ __get_str(function), __entry->line)
);
TRACE_EVENT(consume_skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index 448f390d35d3..3dccd3248de9 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4900,6 +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_FUNC,
SKB_DROP_LINE);
if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8572c3bce264..f7bceb310912 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -761,17 +761,20 @@ EXPORT_SYMBOL(__kfree_skb);
/**
* kfree_skb_reason - free an sk_buff with special reason
* @skb: buffer to free
+ * @func: the function where 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 line to 'kfree_skb' tracepoint.
+ * hit zero. Meanwhile, pass the drop function and line to 'kfree_skb'
+ * tracepoint.
*/
-void kfree_skb_reason(struct sk_buff *skb, unsigned int line)
+void kfree_skb_reason(struct sk_buff *skb, const char *func,
+ unsigned int line)
{
if (!skb_unref(skb))
return;
- trace_kfree_skb(skb, __builtin_return_address(0), line);
+ trace_kfree_skb(skb, __builtin_return_address(0), func, line);
__kfree_skb(skb);
}
EXPORT_SYMBOL(kfree_skb_reason);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f23af94d1186..a1cb1252370b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2149,7 +2149,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
discard_it:
/* Discard frame. */
- kfree_skb_reason(skb, drop_line);
+ kfree_skb_reason(skb, SKB_DROP_FUNC, drop_line);
return 0;
discard_and_relse:
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index f0715d1072d7..ae86ab56a7dd 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2477,7 +2477,7 @@ 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_line);
+ kfree_skb_reason(skb, SKB_DROP_FUNC, drop_line);
return 0;
short_packet:
@@ -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_line);
+ kfree_skb_reason(skb, SKB_DROP_FUNC, drop_line);
return 0;
}
--
2.17.1
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