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Subject: [PATCH net-next 2/3] net: neigh: use kfree_skb_reason() for __neigh_event_send()
Date:   Sun, 20 Feb 2022 23:57:04 +0800
Message-Id: <20220220155705.194266-3-imagedong@tencent.com>
In-Reply-To: <20220220155705.194266-1-imagedong@tencent.com>
References: <20220220155705.194266-1-imagedong@tencent.com>
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From: Menglong Dong <imagedong@tencent.com>

Replace kfree_skb() used in __neigh_event_send() with
kfree_skb_reason(). Following drop reasons are added:

SKB_DROP_REASON_NEIGH_FAILED
SKB_DROP_REASON_NEIGH_QUEUEFULL

The two reasons above should be the hot path that skb drops in
neighbour subsystem.

Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/linux/skbuff.h     | 9 +++++++++
 include/trace/events/skb.h | 2 ++
 net/core/neighbour.c       | 4 ++--
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c310a4a8fc86..206b66f5ce6b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -393,6 +393,15 @@ enum skb_drop_reason {
 					 * see the doc for disable_ipv6
 					 * in ip-sysctl.rst for detail
 					 */
+	SKB_DROP_REASON_NEIGH_FAILED,	/* dropped as the state of
+					 * neighbour is NUD_FAILED
+					 */
+	SKB_DROP_REASON_NEIGH_QUEUEFULL,	/* the skbs that waiting
+						 * for sending on the queue
+						 * of neigh->arp_queue is
+						 * full, and the skbs on the
+						 * tail will be dropped
+						 */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 47dedef7b6b8..dd06366ded4a 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -41,6 +41,8 @@
 	EM(SKB_DROP_REASON_BPF_CGROUP_EGRESS,			\
 	   BPF_CGROUP_EGRESS)					\
 	EM(SKB_DROP_REASON_IPV6DSIABLED, IPV6DSIABLED)		\
+	EM(SKB_DROP_REASON_NEIGH_FAILED, NEIGH_FAILED)		\
+	EM(SKB_DROP_REASON_NEIGH_QUEUEFULL, NEIGH_QUEUEFULL)	\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ec0bf737b076..c353834e8fa9 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1171,7 +1171,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
 			neigh->updated = jiffies;
 			write_unlock_bh(&neigh->lock);
 
-			kfree_skb(skb);
+			kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_FAILED);
 			return 1;
 		}
 	} else if (neigh->nud_state & NUD_STALE) {
@@ -1193,7 +1193,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb,
 				if (!buff)
 					break;
 				neigh->arp_queue_len_bytes -= buff->truesize;
-				kfree_skb(buff);
+				kfree_skb_reason(buff, SKB_DROP_REASON_NEIGH_QUEUEFULL);
 				NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);
 			}
 			skb_dst_force(skb);
-- 
2.35.1