net: skb: rename SKB_DROP_REASON_PTYPE_ABSENT

As David Ahern suggested, the reasons for skb drops should be more
general and not be code based.

Therefore, rename SKB_DROP_REASON_PTYPE_ABSENT to
SKB_DROP_REASON_UNHANDLED_PROTO, which is used for the cases of no
L3 protocol handler, no L4 protocol handler, version extensions, etc.

From previous discussion, now we have the aim to make these reasons
more abstract and users based, avoiding code based.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -408,10 +408,8 @@ enum skb_drop_reason {
 					 */
 	SKB_DROP_REASON_XDP,		/* dropped by XDP in input path */
 	SKB_DROP_REASON_TC_INGRESS,	/* dropped in TC ingress HOOK */
-	SKB_DROP_REASON_PTYPE_ABSENT,	/* not packet_type found to handle
-					 * the skb. For an etner packet,
-					 * this means that L3 protocol is
-					 * not supported
+	SKB_DROP_REASON_UNHANDLED_PROTO,	/* protocol not implemented
+						 * or not supported
 						 */
 	SKB_DROP_REASON_SKB_CSUM,	/* sk_buff checksum computation
 					 * error

include/trace/events/skb.h

@@ -50,7 +50,7 @@
 	EM(SKB_DROP_REASON_CPU_BACKLOG, CPU_BACKLOG)		\
 	EM(SKB_DROP_REASON_XDP, XDP)				\
 	EM(SKB_DROP_REASON_TC_INGRESS, TC_INGRESS)		\
-	EM(SKB_DROP_REASON_PTYPE_ABSENT, PTYPE_ABSENT)		\
+	EM(SKB_DROP_REASON_UNHANDLED_PROTO, UNHANDLED_PROTO)	\
 	EM(SKB_DROP_REASON_SKB_CSUM, SKB_CSUM)			\
 	EM(SKB_DROP_REASON_SKB_GSO_SEG, SKB_GSO_SEG)		\
 	EM(SKB_DROP_REASON_SKB_UCOPY_FAULT, SKB_UCOPY_FAULT)	\

net/core/dev.c

@@ -5375,13 +5375,11 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
 		*ppt_prev = pt_prev;
 	} else {
 drop:
-		if (!deliver_exact) {
+		if (!deliver_exact)
 			dev_core_stats_rx_dropped_inc(skb->dev);
-			kfree_skb_reason(skb, SKB_DROP_REASON_PTYPE_ABSENT);
-		} else {
+		else
 			dev_core_stats_rx_nohandler_inc(skb->dev);
-			kfree_skb(skb);
-		}
+		kfree_skb_reason(skb, SKB_DROP_REASON_UNHANDLED_PROTO);
 		/* Jamal, now you will not able to escape explaining
 		 * me how you were going to use this. :-)
 		 */