From 9cb252c4c1c53ae58bc565bab76e98133288f23a Mon Sep 17 00:00:00 2001 From: Menglong Dong Date: Mon, 5 Sep 2022 11:50:15 +0800 Subject: [PATCH] net: skb: export skb drop reaons to user by TRACE_DEFINE_ENUM 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 Signed-off-by: Menglong Dong Signed-off-by: David S. Miller --- 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 #include +#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 \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 84bb5e188d0d..417463da4fac 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); /**