From 9cb252c4c1c53ae58bc565bab76e98133288f23a Mon Sep 17 00:00:00 2001 From: Menglong Dong Date: Mon, 5 Sep 2022 11:50:15 +0800 Subject: 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 --- net/core/.gitignore | 1 - net/core/Makefile | 22 +--------------------- net/core/skbuff.c | 6 +++++- 3 files changed, 6 insertions(+), 23 deletions(-) delete mode 100644 net/core/.gitignore (limited to 'net/core') 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); /** -- cgit v1.2.3