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Message-Id: <20220905035015.1130730-1-imagedong@tencent.com>
Date: Mon, 5 Sep 2022 11:50:15 +0800
From: menglong8.dong@...il.com
To: edumazet@...gle.com, kuba@...nel.org
Cc: davem@...emloft.net, pabeni@...hat.com, rostedt@...dmis.org,
mingo@...hat.com, imagedong@...cent.com, dsahern@...nel.org,
flyingpeng@...cent.com, dongli.zhang@...cle.com, robh@...nel.org,
asml.silence@...il.com, luiz.von.dentz@...el.com,
vasily.averin@...ux.dev, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: [PATCH net v3] net: skb: export skb drop reaons to user by TRACE_DEFINE_ENUM
From: Menglong Dong <imagedong@...cent.com>
As Eric reported, the 'reason' field is not presented when trace the
kfree_skb event by perf:
$ perf record -e skb:kfree_skb -a sleep 10
$ perf script
ip_defrag 14605 [021] 221.614303: skb:kfree_skb:
skbaddr=0xffff9d2851242700 protocol=34525 location=0xffffffffa39346b1
reason:
The cause seems to be passing kernel address directly to TP_printk(),
which is not right. As the enum 'skb_drop_reason' is not exported to
user space through TRACE_DEFINE_ENUM(), perf can't get the drop reason
string from the 'reason' field, which is a number.
Therefore, we introduce the macro DEFINE_DROP_REASON(), which is used
to define the trace enum by TRACE_DEFINE_ENUM(). With the help of
DEFINE_DROP_REASON(), now we can remove the auto-generate that we
introduced in the commit ec43908dd556
("net: skb: use auto-generation to convert skb drop reason to string"),
and define the string array 'drop_reasons'.
Hmmmm...now we come back to the situation that have to maintain drop
reasons in both enum skb_drop_reason and DEFINE_DROP_REASON. But they
are both in dropreason.h, which makes it easier.
After this commit, now the format of kfree_skb is like this:
$ cat /tracing/events/skb/kfree_skb/format
name: kfree_skb
ID: 1524
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:void * skbaddr; offset:8; size:8; signed:0;
field:void * location; offset:16; size:8; signed:0;
field:unsigned short protocol; offset:24; size:2; signed:0;
field:enum skb_drop_reason reason; offset:28; size:4; signed:0;
print fmt: "skbaddr=%p protocol=%u location=%p reason: %s", REC->skbaddr, REC->protocol, REC->location, __print_symbolic(REC->reason, { 1, "NOT_SPECIFIED" }, { 2, "NO_SOCKET" } ......
Fixes: ec43908dd556 ("net: skb: use auto-generation to convert skb drop reason to string")
Link: https://lore.kernel.org/netdev/CANn89i+bx0ybvE55iMYf5GJM48WwV1HNpdm9Q6t-HaEstqpCSA@mail.gmail.com/
Reported-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Menglong Dong <imagedong@...cent.com>
---
v3:
- add missing Fixes and Link tags (Eric Dumazet)
v2:
- undef FN/FNe after use it (Jakub Kicinski)
---
include/net/dropreason.h | 67 ++++++++++++++++++++++++++++++++++++++
include/trace/events/skb.h | 15 ++++++++-
net/core/.gitignore | 1 -
net/core/Makefile | 22 +------------
net/core/skbuff.c | 6 +++-
5 files changed, 87 insertions(+), 24 deletions(-)
delete mode 100644 net/core/.gitignore
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index fae9b40e54fa..c1cbcdbaf149 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -3,6 +3,73 @@
#ifndef _LINUX_DROPREASON_H
#define _LINUX_DROPREASON_H
+#define DEFINE_DROP_REASON(FN, FNe) \
+ FN(NOT_SPECIFIED) \
+ FN(NO_SOCKET) \
+ FN(PKT_TOO_SMALL) \
+ FN(TCP_CSUM) \
+ FN(SOCKET_FILTER) \
+ FN(UDP_CSUM) \
+ FN(NETFILTER_DROP) \
+ FN(OTHERHOST) \
+ FN(IP_CSUM) \
+ FN(IP_INHDR) \
+ FN(IP_RPFILTER) \
+ FN(UNICAST_IN_L2_MULTICAST) \
+ FN(XFRM_POLICY) \
+ FN(IP_NOPROTO) \
+ FN(SOCKET_RCVBUFF) \
+ FN(PROTO_MEM) \
+ FN(TCP_MD5NOTFOUND) \
+ FN(TCP_MD5UNEXPECTED) \
+ FN(TCP_MD5FAILURE) \
+ FN(SOCKET_BACKLOG) \
+ FN(TCP_FLAGS) \
+ FN(TCP_ZEROWINDOW) \
+ FN(TCP_OLD_DATA) \
+ FN(TCP_OVERWINDOW) \
+ FN(TCP_OFOMERGE) \
+ FN(TCP_RFC7323_PAWS) \
+ FN(TCP_INVALID_SEQUENCE) \
+ FN(TCP_RESET) \
+ FN(TCP_INVALID_SYN) \
+ FN(TCP_CLOSE) \
+ FN(TCP_FASTOPEN) \
+ FN(TCP_OLD_ACK) \
+ FN(TCP_TOO_OLD_ACK) \
+ FN(TCP_ACK_UNSENT_DATA) \
+ FN(TCP_OFO_QUEUE_PRUNE) \
+ FN(TCP_OFO_DROP) \
+ FN(IP_OUTNOROUTES) \
+ FN(BPF_CGROUP_EGRESS) \
+ FN(IPV6DISABLED) \
+ FN(NEIGH_CREATEFAIL) \
+ FN(NEIGH_FAILED) \
+ FN(NEIGH_QUEUEFULL) \
+ FN(NEIGH_DEAD) \
+ FN(TC_EGRESS) \
+ FN(QDISC_DROP) \
+ FN(CPU_BACKLOG) \
+ FN(XDP) \
+ FN(TC_INGRESS) \
+ FN(UNHANDLED_PROTO) \
+ FN(SKB_CSUM) \
+ FN(SKB_GSO_SEG) \
+ FN(SKB_UCOPY_FAULT) \
+ FN(DEV_HDR) \
+ FN(DEV_READY) \
+ FN(FULL_RING) \
+ FN(NOMEM) \
+ FN(HDR_TRUNC) \
+ FN(TAP_FILTER) \
+ FN(TAP_TXFILTER) \
+ FN(ICMP_CSUM) \
+ FN(INVALID_PROTO) \
+ FN(IP_INADDRERRORS) \
+ FN(IP_INNOROUTES) \
+ FN(PKT_TOO_BIG) \
+ FNe(MAX)
+
/**
* enum skb_drop_reason - the reasons of skb drops
*
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 45264e4bb254..50a974f7dfb4 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -9,6 +9,15 @@
#include <linux/netdevice.h>
#include <linux/tracepoint.h>
+#undef FN
+#define FN(reason) TRACE_DEFINE_ENUM(SKB_DROP_REASON_##reason);
+DEFINE_DROP_REASON(FN, FN)
+
+#undef FN
+#undef FNe
+#define FN(reason) { SKB_DROP_REASON_##reason, #reason },
+#define FNe(reason) { SKB_DROP_REASON_##reason, #reason }
+
/*
* Tracepoint for free an sk_buff:
*/
@@ -35,9 +44,13 @@ TRACE_EVENT(kfree_skb,
TP_printk("skbaddr=%p protocol=%u location=%p reason: %s",
__entry->skbaddr, __entry->protocol, __entry->location,
- drop_reasons[__entry->reason])
+ __print_symbolic(__entry->reason,
+ DEFINE_DROP_REASON(FN, FNe)))
);
+#undef FN
+#undef FNe
+
TRACE_EVENT(consume_skb,
TP_PROTO(struct sk_buff *skb),
diff --git a/net/core/.gitignore b/net/core/.gitignore
deleted file mode 100644
index df1e74372cce..000000000000
--- a/net/core/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-dropreason_str.c
diff --git a/net/core/Makefile b/net/core/Makefile
index e8ce3bd283a6..5857cec87b83 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -5,7 +5,7 @@
obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \
gen_stats.o gen_estimator.o net_namespace.o secure_seq.o \
- flow_dissector.o dropreason_str.o
+ flow_dissector.o
obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
@@ -40,23 +40,3 @@ obj-$(CONFIG_NET_SOCK_MSG) += skmsg.o
obj-$(CONFIG_BPF_SYSCALL) += sock_map.o
obj-$(CONFIG_BPF_SYSCALL) += bpf_sk_storage.o
obj-$(CONFIG_OF) += of_net.o
-
-clean-files := dropreason_str.c
-
-quiet_cmd_dropreason_str = GEN $@
-cmd_dropreason_str = awk -F ',' 'BEGIN{ print "\#include <net/dropreason.h>\n"; \
- print "const char * const drop_reasons[] = {" }\
- /^enum skb_drop/ { dr=1; }\
- /^\};/ { dr=0; }\
- /^\tSKB_DROP_REASON_/ {\
- if (dr) {\
- sub(/\tSKB_DROP_REASON_/, "", $$1);\
- printf "\t[SKB_DROP_REASON_%s] = \"%s\",\n", $$1, $$1;\
- }\
- }\
- END{ print "};" }' $< > $@
-
-$(obj)/dropreason_str.c: $(srctree)/include/net/dropreason.h
- $(call cmd,dropreason_str)
-
-$(obj)/dropreason_str.o: $(obj)/dropreason_str.c
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 48ecfbf29174..f1b8b20fc20b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -91,7 +91,11 @@ static struct kmem_cache *skbuff_ext_cache __ro_after_init;
int sysctl_max_skb_frags __read_mostly = MAX_SKB_FRAGS;
EXPORT_SYMBOL(sysctl_max_skb_frags);
-/* The array 'drop_reasons' is auto-generated in dropreason_str.c */
+#undef FN
+#define FN(reason) [SKB_DROP_REASON_##reason] = #reason,
+const char * const drop_reasons[] = {
+ DEFINE_DROP_REASON(FN, FN)
+};
EXPORT_SYMBOL(drop_reasons);
/**
--
2.37.2
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