diff mbox series

[RFC,2/4] net: dropreason: use new __print_sym() in tracing

Message ID 20230921105129.2f2774a87760.I075de1ac698b47710b94c631afdfb328f07be961@changeid (mailing list archive)
State RFC
Delegated to: Netdev Maintainers
Headers show
Series tracing: improve symbolic printing | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Guessed tree name to be net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit fail Errors and warnings before: 1424 this patch: 1428
netdev/cc_maintainers warning 7 maintainers not CCed: rostedt@goodmis.org pabeni@redhat.com davem@davemloft.net edumazet@google.com sdf@google.com mhiramat@kernel.org kuba@kernel.org
netdev/build_clang fail Errors and warnings before: 77 this patch: 79
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn fail Errors and warnings before: 521 this patch: 112
netdev/checkpatch fail ERROR: space prohibited before that close parenthesis ')' WARNING: line length of 82 exceeds 80 columns WARNING: line length of 83 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Johannes Berg Sept. 21, 2023, 8:51 a.m. UTC
From: Johannes Berg <johannes.berg@intel.com>

The __print_symbolic() could only ever print the core
drop reasons, since that's the way the infrastructure
works. Now that we have __print_sym() with all the
advantages mentioned in that commit, convert to that
and get all the drop reasons from all subsystems. As
we already have a list of them, that's really easy.

This is a little bit of .text (~100 bytes in my build)
and saves a lot of .data (~17k).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 include/net/dropreason.h   |  5 +++++
 include/trace/events/skb.h | 16 +++-----------
 net/core/skbuff.c          | 43 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 13 deletions(-)
diff mbox series

Patch

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index 56cb7be92244..c157070b5303 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -42,6 +42,11 @@  struct drop_reason_list {
 extern const struct drop_reason_list __rcu *
 drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM];
 
+#ifdef CONFIG_TRACEPOINTS
+const char *drop_reason_lookup(unsigned long long value);
+void drop_reason_show(struct seq_file *m);
+#endif
+
 void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
 				  const struct drop_reason_list *list);
 void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys);
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 07e0715628ec..8a1a63f9e796 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -8,15 +8,9 @@ 
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/tracepoint.h>
+#include <net/dropreason.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 }
+TRACE_DEFINE_SYM_FNS(drop_reason, drop_reason_lookup, drop_reason_show);
 
 /*
  * Tracepoint for free an sk_buff:
@@ -44,13 +38,9 @@  TRACE_EVENT(kfree_skb,
 
 	TP_printk("skbaddr=%p protocol=%u location=%pS reason: %s",
 		  __entry->skbaddr, __entry->protocol, __entry->location,
-		  __print_symbolic(__entry->reason,
-				   DEFINE_DROP_REASON(FN, FNe)))
+		  __print_sym(__entry->reason, drop_reason ))
 );
 
-#undef FN
-#undef FNe
-
 TRACE_EVENT(consume_skb,
 
 	TP_PROTO(struct sk_buff *skb, void *location),
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4eaf7ed0d1f4..415329b76921 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -132,6 +132,49 @@  drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
 };
 EXPORT_SYMBOL(drop_reasons_by_subsys);
 
+#ifdef CONFIG_TRACEPOINTS
+const char *drop_reason_lookup(unsigned long long value)
+{
+	unsigned long long subsys_id = value >> SKB_DROP_REASON_SUBSYS_SHIFT;
+	u32 reason = value & ~SKB_DROP_REASON_SUBSYS_MASK;
+	const struct drop_reason_list *subsys;
+
+	if (subsys_id >= SKB_DROP_REASON_SUBSYS_NUM)
+		return NULL;
+
+	subsys = rcu_dereference(drop_reasons_by_subsys[subsys_id]);
+	if (!subsys)
+		return NULL;
+	if (reason >= subsys->n_reasons)
+		return NULL;
+	return subsys->reasons[reason];
+}
+
+void drop_reason_show(struct seq_file *m)
+{
+	u32 subsys_id;
+
+	rcu_read_lock();
+	for (subsys_id = 0; subsys_id < SKB_DROP_REASON_SUBSYS_NUM; subsys_id++) {
+		const struct drop_reason_list *subsys;
+		u32 i;
+
+		subsys = rcu_dereference(drop_reasons_by_subsys[subsys_id]);
+		if (!subsys)
+			continue;
+
+		for (i = 0; i < subsys->n_reasons; i++) {
+			if (!subsys->reasons[i])
+				continue;
+			seq_printf(m, ", { %u, \"%s\" }",
+				   (subsys_id << SKB_DROP_REASON_SUBSYS_SHIFT) | i,
+				   subsys->reasons[i]);
+		}
+	}
+	rcu_read_unlock();
+}
+#endif
+
 /**
  * drop_reasons_register_subsys - register another drop reason subsystem
  * @subsys: the subsystem to register, must not be the core