[PATCH net-next v2 0/3] reorganize the code of the enum skb_drop_reason

[PATCH net-next v2 0/3] reorganize the code of the enum skb_drop_reason

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

The code of skb_drop_reason is a little wild, let's reorganize them.
Three things and three patches:

1) Move the enum 'skb_drop_reason' and related function to the standalone
   header 'dropreason.h', as Jakub Kicinski suggested, as the skb drop
   reasons are getting more and more.

2) use auto-generation to generate the source file that convert enum
   skb_drop_reason to string.

3) make the comment of skb drop reasons kernel-doc style.

Changes since v1:
1/3: move dropreason.h from include/linux/ to include/net/ (Jakub Kicinski)
2/3: generate source file instead of header file for drop reasons string
     array (Jakub Kicinski)
3/3: use inline comment (Jakub Kicinski)

Menglong Dong (3):
  net: skb: move enum skb_drop_reason to standalone header file
  net: skb: use auto-generation to convert skb drop reason to string
  net: dropreason: reformat the comment fo skb drop reasons

 include/linux/skbuff.h     | 179 +------------------------
 include/net/dropreason.h   | 259 +++++++++++++++++++++++++++++++++++++
 include/trace/events/skb.h |  89 +------------
 net/core/.gitignore        |   1 +
 net/core/Makefile          |  23 +++-
 net/core/drop_monitor.c    |  13 --
 6 files changed, 284 insertions(+), 280 deletions(-)
 create mode 100644 include/net/dropreason.h
 create mode 100644 net/core/.gitignore

-- 
2.36.1

[PATCH net-next v2 1/3] net: skb: move enum skb_drop_reason to standalone header file

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

As the skb drop reasons are getting more and more, move the enum
'skb_drop_reason' and related function to the standalone header
'dropreason.h', as Jakub Kicinski suggested.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/linux/skbuff.h   | 179 +------------------------------------
 include/net/dropreason.h | 184 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 185 insertions(+), 178 deletions(-)
 create mode 100644 include/net/dropreason.h

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index da96f0d3e753..69cd1c6f1862 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -43,6 +43,7 @@
 #include <linux/netfilter/nf_conntrack_common.h>
 #endif
 #include <net/net_debug.h>
+#include <net/dropreason.h>
 
 /**
  * DOC: skb checksums
@@ -337,184 +338,6 @@ struct sk_buff_head {
 
 struct sk_buff;
 
-/* The reason of skb drop, which is used in kfree_skb_reason().
- * en...maybe they should be splited by group?
- *
- * Each item here should also be in 'TRACE_SKB_DROP_REASON', which is
- * used to translate the reason to string.
- */
-enum skb_drop_reason {
-	SKB_NOT_DROPPED_YET = 0,
-	SKB_DROP_REASON_NOT_SPECIFIED,	/* drop reason is not specified */
-	SKB_DROP_REASON_NO_SOCKET,	/* socket not found */
-	SKB_DROP_REASON_PKT_TOO_SMALL,	/* packet size is too small */
-	SKB_DROP_REASON_TCP_CSUM,	/* TCP checksum error */
-	SKB_DROP_REASON_SOCKET_FILTER,	/* dropped by socket filter */
-	SKB_DROP_REASON_UDP_CSUM,	/* UDP checksum error */
-	SKB_DROP_REASON_NETFILTER_DROP,	/* dropped by netfilter */
-	SKB_DROP_REASON_OTHERHOST,	/* packet don't belong to current
-					 * host (interface is in promisc
-					 * mode)
-					 */
-	SKB_DROP_REASON_IP_CSUM,	/* IP checksum error */
-	SKB_DROP_REASON_IP_INHDR,	/* there is something wrong with
-					 * IP header (see
-					 * IPSTATS_MIB_INHDRERRORS)
-					 */
-	SKB_DROP_REASON_IP_RPFILTER,	/* IP rpfilter validate failed.
-					 * see the document for rp_filter
-					 * in ip-sysctl.rst for more
-					 * information
-					 */
-	SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST, /* destination address of L2
-						  * is multicast, but L3 is
-						  * unicast.
-						  */
-	SKB_DROP_REASON_XFRM_POLICY,	/* xfrm policy check failed */
-	SKB_DROP_REASON_IP_NOPROTO,	/* no support for IP protocol */
-	SKB_DROP_REASON_SOCKET_RCVBUFF,	/* socket receive buff is full */
-	SKB_DROP_REASON_PROTO_MEM,	/* proto memory limition, such as
-					 * udp packet drop out of
-					 * udp_memory_allocated.
-					 */
-	SKB_DROP_REASON_TCP_MD5NOTFOUND,	/* no MD5 hash and one
-						 * expected, corresponding
-						 * to LINUX_MIB_TCPMD5NOTFOUND
-						 */
-	SKB_DROP_REASON_TCP_MD5UNEXPECTED,	/* MD5 hash and we're not
-						 * expecting one, corresponding
-						 * to LINUX_MIB_TCPMD5UNEXPECTED
-						 */
-	SKB_DROP_REASON_TCP_MD5FAILURE,	/* MD5 hash and its wrong,
-					 * corresponding to
-					 * LINUX_MIB_TCPMD5FAILURE
-					 */
-	SKB_DROP_REASON_SOCKET_BACKLOG,	/* failed to add skb to socket
-					 * backlog (see
-					 * LINUX_MIB_TCPBACKLOGDROP)
-					 */
-	SKB_DROP_REASON_TCP_FLAGS,	/* TCP flags invalid */
-	SKB_DROP_REASON_TCP_ZEROWINDOW,	/* TCP receive window size is zero,
-					 * see LINUX_MIB_TCPZEROWINDOWDROP
-					 */
-	SKB_DROP_REASON_TCP_OLD_DATA,	/* the TCP data reveived is already
-					 * received before (spurious retrans
-					 * may happened), see
-					 * LINUX_MIB_DELAYEDACKLOST
-					 */
-	SKB_DROP_REASON_TCP_OVERWINDOW,	/* the TCP data is out of window,
-					 * the seq of the first byte exceed
-					 * the right edges of receive
-					 * window
-					 */
-	SKB_DROP_REASON_TCP_OFOMERGE,	/* the data of skb is already in
-					 * the ofo queue, corresponding to
-					 * LINUX_MIB_TCPOFOMERGE
-					 */
-	SKB_DROP_REASON_TCP_RFC7323_PAWS, /* PAWS check, corresponding to
-					   * LINUX_MIB_PAWSESTABREJECTED
-					   */
-	SKB_DROP_REASON_TCP_INVALID_SEQUENCE, /* Not acceptable SEQ field */
-	SKB_DROP_REASON_TCP_RESET,	/* Invalid RST packet */
-	SKB_DROP_REASON_TCP_INVALID_SYN, /* Incoming packet has unexpected SYN flag */
-	SKB_DROP_REASON_TCP_CLOSE,	/* TCP socket in CLOSE state */
-	SKB_DROP_REASON_TCP_FASTOPEN,	/* dropped by FASTOPEN request socket */
-	SKB_DROP_REASON_TCP_OLD_ACK,	/* TCP ACK is old, but in window */
-	SKB_DROP_REASON_TCP_TOO_OLD_ACK, /* TCP ACK is too old */
-	SKB_DROP_REASON_TCP_ACK_UNSENT_DATA, /* TCP ACK for data we haven't sent yet */
-	SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE, /* pruned from TCP OFO queue */
-	SKB_DROP_REASON_TCP_OFO_DROP,	/* data already in receive queue */
-	SKB_DROP_REASON_IP_OUTNOROUTES,	/* route lookup failed */
-	SKB_DROP_REASON_BPF_CGROUP_EGRESS,	/* dropped by
-						 * BPF_PROG_TYPE_CGROUP_SKB
-						 * eBPF program
-						 */
-	SKB_DROP_REASON_IPV6DISABLED,	/* IPv6 is disabled on the device */
-	SKB_DROP_REASON_NEIGH_CREATEFAIL,	/* failed to create neigh
-						 * entry
-						 */
-	SKB_DROP_REASON_NEIGH_FAILED,	/* neigh entry in failed state */
-	SKB_DROP_REASON_NEIGH_QUEUEFULL,	/* arp_queue for neigh
-						 * entry is full
-						 */
-	SKB_DROP_REASON_NEIGH_DEAD,	/* neigh entry is dead */
-	SKB_DROP_REASON_TC_EGRESS,	/* dropped in TC egress HOOK */
-	SKB_DROP_REASON_QDISC_DROP,	/* dropped by qdisc when packet
-					 * outputting (failed to enqueue to
-					 * current qdisc)
-					 */
-	SKB_DROP_REASON_CPU_BACKLOG,	/* failed to enqueue the skb to
-					 * the per CPU backlog queue. This
-					 * can be caused by backlog queue
-					 * full (see netdev_max_backlog in
-					 * net.rst) or RPS flow limit
-					 */
-	SKB_DROP_REASON_XDP,		/* dropped by XDP in input path */
-	SKB_DROP_REASON_TC_INGRESS,	/* dropped in TC ingress HOOK */
-	SKB_DROP_REASON_UNHANDLED_PROTO,	/* protocol not implemented
-						 * or not supported
-						 */
-	SKB_DROP_REASON_SKB_CSUM,	/* sk_buff checksum computation
-					 * error
-					 */
-	SKB_DROP_REASON_SKB_GSO_SEG,	/* gso segmentation error */
-	SKB_DROP_REASON_SKB_UCOPY_FAULT,	/* failed to copy data from
-						 * user space, e.g., via
-						 * zerocopy_sg_from_iter()
-						 * or skb_orphan_frags_rx()
-						 */
-	SKB_DROP_REASON_DEV_HDR,	/* device driver specific
-					 * header/metadata is invalid
-					 */
-	/* the device is not ready to xmit/recv due to any of its data
-	 * structure that is not up/ready/initialized, e.g., the IFF_UP is
-	 * not set, or driver specific tun->tfiles[txq] is not initialized
-	 */
-	SKB_DROP_REASON_DEV_READY,
-	SKB_DROP_REASON_FULL_RING,	/* ring buffer is full */
-	SKB_DROP_REASON_NOMEM,		/* error due to OOM */
-	SKB_DROP_REASON_HDR_TRUNC,      /* failed to trunc/extract the header
-					 * from networking data, e.g., failed
-					 * to pull the protocol header from
-					 * frags via pskb_may_pull()
-					 */
-	SKB_DROP_REASON_TAP_FILTER,     /* dropped by (ebpf) filter directly
-					 * attached to tun/tap, e.g., via
-					 * TUNSETFILTEREBPF
-					 */
-	SKB_DROP_REASON_TAP_TXFILTER,	/* dropped by tx filter implemented
-					 * at tun/tap, e.g., check_filter()
-					 */
-	SKB_DROP_REASON_ICMP_CSUM,	/* ICMP checksum error */
-	SKB_DROP_REASON_INVALID_PROTO,	/* the packet doesn't follow RFC
-					 * 2211, such as a broadcasts
-					 * ICMP_TIMESTAMP
-					 */
-	SKB_DROP_REASON_IP_INADDRERRORS,	/* host unreachable, corresponding
-						 * to IPSTATS_MIB_INADDRERRORS
-						 */
-	SKB_DROP_REASON_IP_INNOROUTES,	/* network unreachable, corresponding
-					 * to IPSTATS_MIB_INADDRERRORS
-					 */
-	SKB_DROP_REASON_PKT_TOO_BIG,	/* packet size is too big (maybe exceed
-					 * the MTU)
-					 */
-	SKB_DROP_REASON_MAX,
-};
-
-#define SKB_DR_INIT(name, reason)				\
-	enum skb_drop_reason name = SKB_DROP_REASON_##reason
-#define SKB_DR(name)						\
-	SKB_DR_INIT(name, NOT_SPECIFIED)
-#define SKB_DR_SET(name, reason)				\
-	(name = SKB_DROP_REASON_##reason)
-#define SKB_DR_OR(name, reason)					\
-	do {							\
-		if (name == SKB_DROP_REASON_NOT_SPECIFIED ||	\
-		    name == SKB_NOT_DROPPED_YET)		\
-			SKB_DR_SET(name, reason);		\
-	} while (0)
-
 /* To allow 64K frame to be packed as single skb without frag_list we
  * require 64K/PAGE_SIZE pages plus 1 additional page to allow for
  * buffers which do not start on a page boundary.
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
new file mode 100644
index 000000000000..ecd18b7b1364
--- /dev/null
+++ b/include/net/dropreason.h
@@ -0,0 +1,184 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _LINUX_DROPREASON_H
+#define _LINUX_DROPREASON_H
+
+/* The reason of skb drop, which is used in kfree_skb_reason().
+ * en...maybe they should be splited by group?
+ *
+ * Each item here should also be in 'TRACE_SKB_DROP_REASON', which is
+ * used to translate the reason to string.
+ */
+enum skb_drop_reason {
+	SKB_NOT_DROPPED_YET = 0,
+	SKB_DROP_REASON_NOT_SPECIFIED,	/* drop reason is not specified */
+	SKB_DROP_REASON_NO_SOCKET,	/* socket not found */
+	SKB_DROP_REASON_PKT_TOO_SMALL,	/* packet size is too small */
+	SKB_DROP_REASON_TCP_CSUM,	/* TCP checksum error */
+	SKB_DROP_REASON_SOCKET_FILTER,	/* dropped by socket filter */
+	SKB_DROP_REASON_UDP_CSUM,	/* UDP checksum error */
+	SKB_DROP_REASON_NETFILTER_DROP,	/* dropped by netfilter */
+	SKB_DROP_REASON_OTHERHOST,	/* packet don't belong to current
+					 * host (interface is in promisc
+					 * mode)
+					 */
+	SKB_DROP_REASON_IP_CSUM,	/* IP checksum error */
+	SKB_DROP_REASON_IP_INHDR,	/* there is something wrong with
+					 * IP header (see
+					 * IPSTATS_MIB_INHDRERRORS)
+					 */
+	SKB_DROP_REASON_IP_RPFILTER,	/* IP rpfilter validate failed.
+					 * see the document for rp_filter
+					 * in ip-sysctl.rst for more
+					 * information
+					 */
+	SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST, /* destination address of L2
+						  * is multicast, but L3 is
+						  * unicast.
+						  */
+	SKB_DROP_REASON_XFRM_POLICY,	/* xfrm policy check failed */
+	SKB_DROP_REASON_IP_NOPROTO,	/* no support for IP protocol */
+	SKB_DROP_REASON_SOCKET_RCVBUFF,	/* socket receive buff is full */
+	SKB_DROP_REASON_PROTO_MEM,	/* proto memory limition, such as
+					 * udp packet drop out of
+					 * udp_memory_allocated.
+					 */
+	SKB_DROP_REASON_TCP_MD5NOTFOUND,	/* no MD5 hash and one
+						 * expected, corresponding
+						 * to LINUX_MIB_TCPMD5NOTFOUND
+						 */
+	SKB_DROP_REASON_TCP_MD5UNEXPECTED,	/* MD5 hash and we're not
+						 * expecting one, corresponding
+						 * to LINUX_MIB_TCPMD5UNEXPECTED
+						 */
+	SKB_DROP_REASON_TCP_MD5FAILURE,	/* MD5 hash and its wrong,
+					 * corresponding to
+					 * LINUX_MIB_TCPMD5FAILURE
+					 */
+	SKB_DROP_REASON_SOCKET_BACKLOG,	/* failed to add skb to socket
+					 * backlog (see
+					 * LINUX_MIB_TCPBACKLOGDROP)
+					 */
+	SKB_DROP_REASON_TCP_FLAGS,	/* TCP flags invalid */
+	SKB_DROP_REASON_TCP_ZEROWINDOW,	/* TCP receive window size is zero,
+					 * see LINUX_MIB_TCPZEROWINDOWDROP
+					 */
+	SKB_DROP_REASON_TCP_OLD_DATA,	/* the TCP data reveived is already
+					 * received before (spurious retrans
+					 * may happened), see
+					 * LINUX_MIB_DELAYEDACKLOST
+					 */
+	SKB_DROP_REASON_TCP_OVERWINDOW,	/* the TCP data is out of window,
+					 * the seq of the first byte exceed
+					 * the right edges of receive
+					 * window
+					 */
+	SKB_DROP_REASON_TCP_OFOMERGE,	/* the data of skb is already in
+					 * the ofo queue, corresponding to
+					 * LINUX_MIB_TCPOFOMERGE
+					 */
+	SKB_DROP_REASON_TCP_RFC7323_PAWS, /* PAWS check, corresponding to
+					   * LINUX_MIB_PAWSESTABREJECTED
+					   */
+	SKB_DROP_REASON_TCP_INVALID_SEQUENCE, /* Not acceptable SEQ field */
+	SKB_DROP_REASON_TCP_RESET,	/* Invalid RST packet */
+	SKB_DROP_REASON_TCP_INVALID_SYN, /* Incoming packet has unexpected SYN flag */
+	SKB_DROP_REASON_TCP_CLOSE,	/* TCP socket in CLOSE state */
+	SKB_DROP_REASON_TCP_FASTOPEN,	/* dropped by FASTOPEN request socket */
+	SKB_DROP_REASON_TCP_OLD_ACK,	/* TCP ACK is old, but in window */
+	SKB_DROP_REASON_TCP_TOO_OLD_ACK, /* TCP ACK is too old */
+	SKB_DROP_REASON_TCP_ACK_UNSENT_DATA, /* TCP ACK for data we haven't sent yet */
+	SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE, /* pruned from TCP OFO queue */
+	SKB_DROP_REASON_TCP_OFO_DROP,	/* data already in receive queue */
+	SKB_DROP_REASON_IP_OUTNOROUTES,	/* route lookup failed */
+	SKB_DROP_REASON_BPF_CGROUP_EGRESS,	/* dropped by
+						 * BPF_PROG_TYPE_CGROUP_SKB
+						 * eBPF program
+						 */
+	SKB_DROP_REASON_IPV6DISABLED,	/* IPv6 is disabled on the device */
+	SKB_DROP_REASON_NEIGH_CREATEFAIL,	/* failed to create neigh
+						 * entry
+						 */
+	SKB_DROP_REASON_NEIGH_FAILED,	/* neigh entry in failed state */
+	SKB_DROP_REASON_NEIGH_QUEUEFULL,	/* arp_queue for neigh
+						 * entry is full
+						 */
+	SKB_DROP_REASON_NEIGH_DEAD,	/* neigh entry is dead */
+	SKB_DROP_REASON_TC_EGRESS,	/* dropped in TC egress HOOK */
+	SKB_DROP_REASON_QDISC_DROP,	/* dropped by qdisc when packet
+					 * outputting (failed to enqueue to
+					 * current qdisc)
+					 */
+	SKB_DROP_REASON_CPU_BACKLOG,	/* failed to enqueue the skb to
+					 * the per CPU backlog queue. This
+					 * can be caused by backlog queue
+					 * full (see netdev_max_backlog in
+					 * net.rst) or RPS flow limit
+					 */
+	SKB_DROP_REASON_XDP,		/* dropped by XDP in input path */
+	SKB_DROP_REASON_TC_INGRESS,	/* dropped in TC ingress HOOK */
+	SKB_DROP_REASON_UNHANDLED_PROTO,	/* protocol not implemented
+						 * or not supported
+						 */
+	SKB_DROP_REASON_SKB_CSUM,	/* sk_buff checksum computation
+					 * error
+					 */
+	SKB_DROP_REASON_SKB_GSO_SEG,	/* gso segmentation error */
+	SKB_DROP_REASON_SKB_UCOPY_FAULT,	/* failed to copy data from
+						 * user space, e.g., via
+						 * zerocopy_sg_from_iter()
+						 * or skb_orphan_frags_rx()
+						 */
+	SKB_DROP_REASON_DEV_HDR,	/* device driver specific
+					 * header/metadata is invalid
+					 */
+	/* the device is not ready to xmit/recv due to any of its data
+	 * structure that is not up/ready/initialized, e.g., the IFF_UP is
+	 * not set, or driver specific tun->tfiles[txq] is not initialized
+	 */
+	SKB_DROP_REASON_DEV_READY,
+	SKB_DROP_REASON_FULL_RING,	/* ring buffer is full */
+	SKB_DROP_REASON_NOMEM,		/* error due to OOM */
+	SKB_DROP_REASON_HDR_TRUNC,      /* failed to trunc/extract the header
+					 * from networking data, e.g., failed
+					 * to pull the protocol header from
+					 * frags via pskb_may_pull()
+					 */
+	SKB_DROP_REASON_TAP_FILTER,     /* dropped by (ebpf) filter directly
+					 * attached to tun/tap, e.g., via
+					 * TUNSETFILTEREBPF
+					 */
+	SKB_DROP_REASON_TAP_TXFILTER,	/* dropped by tx filter implemented
+					 * at tun/tap, e.g., check_filter()
+					 */
+	SKB_DROP_REASON_ICMP_CSUM,	/* ICMP checksum error */
+	SKB_DROP_REASON_INVALID_PROTO,	/* the packet doesn't follow RFC
+					 * 2211, such as a broadcasts
+					 * ICMP_TIMESTAMP
+					 */
+	SKB_DROP_REASON_IP_INADDRERRORS,	/* host unreachable, corresponding
+						 * to IPSTATS_MIB_INADDRERRORS
+						 */
+	SKB_DROP_REASON_IP_INNOROUTES,	/* network unreachable, corresponding
+					 * to IPSTATS_MIB_INADDRERRORS
+					 */
+	SKB_DROP_REASON_PKT_TOO_BIG,	/* packet size is too big (maybe exceed
+					 * the MTU)
+					 */
+	SKB_DROP_REASON_MAX,
+};
+
+#define SKB_DR_INIT(name, reason)				\
+	enum skb_drop_reason name = SKB_DROP_REASON_##reason
+#define SKB_DR(name)						\
+	SKB_DR_INIT(name, NOT_SPECIFIED)
+#define SKB_DR_SET(name, reason)				\
+	(name = SKB_DROP_REASON_##reason)
+#define SKB_DR_OR(name, reason)					\
+	do {							\
+		if (name == SKB_DROP_REASON_NOT_SPECIFIED ||	\
+		    name == SKB_NOT_DROPPED_YET)		\
+			SKB_DR_SET(name, reason);		\
+	} while (0)
+
+#endif
-- 
2.36.1

[PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

It is annoying to add new skb drop reasons to 'enum skb_drop_reason'
and TRACE_SKB_DROP_REASON in trace/event/skb.h, and it's easy to forget
to add the new reasons we added to TRACE_SKB_DROP_REASON.

TRACE_SKB_DROP_REASON is used to convert drop reason of type number
to string. For now, the string we passed to user space is exactly the
same as the name in 'enum skb_drop_reason' with a 'SKB_DROP_REASON_'
prefix. Therefore, we can use 'auto-generation' to generate these
drop reasons to string at build time.

The new header 'dropreason_str.h' will be generated, and the
__DEFINE_SKB_DROP_REASON() in it can do the converting job. Meanwhile,
we use a global array to store these string, which can be used both
in drop_monitor and 'kfree_skb' tracepoint.

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
 include/net/dropreason.h   |  4 ++
 include/trace/events/skb.h | 89 +-------------------------------------
 net/core/.gitignore        |  1 +
 net/core/Makefile          | 23 +++++++++-
 net/core/drop_monitor.c    | 13 ------
 5 files changed, 28 insertions(+), 102 deletions(-)
 create mode 100644 net/core/.gitignore

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index ecd18b7b1364..460de425297c 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -3,6 +3,8 @@
 #ifndef _LINUX_DROPREASON_H
 #define _LINUX_DROPREASON_H
 
+#include <linux/kernel.h>
+
 /* The reason of skb drop, which is used in kfree_skb_reason().
  * en...maybe they should be splited by group?
  *
@@ -181,4 +183,6 @@ enum skb_drop_reason {
 			SKB_DR_SET(name, reason);		\
 	} while (0)
 
+extern const char * const drop_reasons[];
+
 #endif
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index a477bf907498..45264e4bb254 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -9,92 +9,6 @@
 #include <linux/netdevice.h>
 #include <linux/tracepoint.h>
 
-#define TRACE_SKB_DROP_REASON					\
-	EM(SKB_DROP_REASON_NOT_SPECIFIED, NOT_SPECIFIED)	\
-	EM(SKB_DROP_REASON_NO_SOCKET, NO_SOCKET)		\
-	EM(SKB_DROP_REASON_PKT_TOO_SMALL, PKT_TOO_SMALL)	\
-	EM(SKB_DROP_REASON_TCP_CSUM, TCP_CSUM)			\
-	EM(SKB_DROP_REASON_SOCKET_FILTER, SOCKET_FILTER)	\
-	EM(SKB_DROP_REASON_UDP_CSUM, UDP_CSUM)			\
-	EM(SKB_DROP_REASON_NETFILTER_DROP, NETFILTER_DROP)	\
-	EM(SKB_DROP_REASON_OTHERHOST, OTHERHOST)		\
-	EM(SKB_DROP_REASON_IP_CSUM, IP_CSUM)			\
-	EM(SKB_DROP_REASON_IP_INHDR, IP_INHDR)			\
-	EM(SKB_DROP_REASON_IP_RPFILTER, IP_RPFILTER)		\
-	EM(SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST,		\
-	   UNICAST_IN_L2_MULTICAST)				\
-	EM(SKB_DROP_REASON_XFRM_POLICY, XFRM_POLICY)		\
-	EM(SKB_DROP_REASON_IP_NOPROTO, IP_NOPROTO)		\
-	EM(SKB_DROP_REASON_SOCKET_RCVBUFF, SOCKET_RCVBUFF)	\
-	EM(SKB_DROP_REASON_PROTO_MEM, PROTO_MEM)		\
-	EM(SKB_DROP_REASON_TCP_MD5NOTFOUND, TCP_MD5NOTFOUND)	\
-	EM(SKB_DROP_REASON_TCP_MD5UNEXPECTED,			\
-	   TCP_MD5UNEXPECTED)					\
-	EM(SKB_DROP_REASON_TCP_MD5FAILURE, TCP_MD5FAILURE)	\
-	EM(SKB_DROP_REASON_SOCKET_BACKLOG, SOCKET_BACKLOG)	\
-	EM(SKB_DROP_REASON_TCP_FLAGS, TCP_FLAGS)		\
-	EM(SKB_DROP_REASON_TCP_ZEROWINDOW, TCP_ZEROWINDOW)	\
-	EM(SKB_DROP_REASON_TCP_OLD_DATA, TCP_OLD_DATA)		\
-	EM(SKB_DROP_REASON_TCP_OVERWINDOW, TCP_OVERWINDOW)	\
-	EM(SKB_DROP_REASON_TCP_OFOMERGE, TCP_OFOMERGE)		\
-	EM(SKB_DROP_REASON_TCP_OFO_DROP, TCP_OFO_DROP)		\
-	EM(SKB_DROP_REASON_TCP_RFC7323_PAWS, TCP_RFC7323_PAWS)	\
-	EM(SKB_DROP_REASON_TCP_INVALID_SEQUENCE,		\
-	   TCP_INVALID_SEQUENCE)				\
-	EM(SKB_DROP_REASON_TCP_RESET, TCP_RESET)		\
-	EM(SKB_DROP_REASON_TCP_INVALID_SYN, TCP_INVALID_SYN)	\
-	EM(SKB_DROP_REASON_TCP_CLOSE, TCP_CLOSE)		\
-	EM(SKB_DROP_REASON_TCP_FASTOPEN, TCP_FASTOPEN)		\
-	EM(SKB_DROP_REASON_TCP_OLD_ACK, TCP_OLD_ACK)		\
-	EM(SKB_DROP_REASON_TCP_TOO_OLD_ACK, TCP_TOO_OLD_ACK)	\
-	EM(SKB_DROP_REASON_TCP_ACK_UNSENT_DATA,			\
-	   TCP_ACK_UNSENT_DATA)					\
-	EM(SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE,			\
-	  TCP_OFO_QUEUE_PRUNE)					\
-	EM(SKB_DROP_REASON_IP_OUTNOROUTES, IP_OUTNOROUTES)	\
-	EM(SKB_DROP_REASON_BPF_CGROUP_EGRESS,			\
-	   BPF_CGROUP_EGRESS)					\
-	EM(SKB_DROP_REASON_IPV6DISABLED, IPV6DISABLED)		\
-	EM(SKB_DROP_REASON_NEIGH_CREATEFAIL, NEIGH_CREATEFAIL)	\
-	EM(SKB_DROP_REASON_NEIGH_FAILED, NEIGH_FAILED)		\
-	EM(SKB_DROP_REASON_NEIGH_QUEUEFULL, NEIGH_QUEUEFULL)	\
-	EM(SKB_DROP_REASON_NEIGH_DEAD, NEIGH_DEAD)		\
-	EM(SKB_DROP_REASON_TC_EGRESS, TC_EGRESS)		\
-	EM(SKB_DROP_REASON_QDISC_DROP, QDISC_DROP)		\
-	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_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)	\
-	EM(SKB_DROP_REASON_DEV_HDR, DEV_HDR)			\
-	EM(SKB_DROP_REASON_DEV_READY, DEV_READY)		\
-	EM(SKB_DROP_REASON_FULL_RING, FULL_RING)		\
-	EM(SKB_DROP_REASON_NOMEM, NOMEM)			\
-	EM(SKB_DROP_REASON_HDR_TRUNC, HDR_TRUNC)		\
-	EM(SKB_DROP_REASON_TAP_FILTER, TAP_FILTER)		\
-	EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER)		\
-	EM(SKB_DROP_REASON_ICMP_CSUM, ICMP_CSUM)		\
-	EM(SKB_DROP_REASON_INVALID_PROTO, INVALID_PROTO)	\
-	EM(SKB_DROP_REASON_IP_INADDRERRORS, IP_INADDRERRORS)	\
-	EM(SKB_DROP_REASON_IP_INNOROUTES, IP_INNOROUTES)	\
-	EM(SKB_DROP_REASON_PKT_TOO_BIG, PKT_TOO_BIG)		\
-	EMe(SKB_DROP_REASON_MAX, MAX)
-
-#undef EM
-#undef EMe
-
-#define EM(a, b)	TRACE_DEFINE_ENUM(a);
-#define EMe(a, b)	TRACE_DEFINE_ENUM(a);
-
-TRACE_SKB_DROP_REASON
-
-#undef EM
-#undef EMe
-#define EM(a, b)	{ a, #b },
-#define EMe(a, b)	{ a, #b }
-
 /*
  * Tracepoint for free an sk_buff:
  */
@@ -121,8 +35,7 @@ TRACE_EVENT(kfree_skb,
 
 	TP_printk("skbaddr=%p protocol=%u location=%p reason: %s",
 		  __entry->skbaddr, __entry->protocol, __entry->location,
-		  __print_symbolic(__entry->reason,
-				   TRACE_SKB_DROP_REASON))
+		  drop_reasons[__entry->reason])
 );
 
 TRACE_EVENT(consume_skb,
diff --git a/net/core/.gitignore b/net/core/.gitignore
new file mode 100644
index 000000000000..104e30010785
--- /dev/null
+++ b/net/core/.gitignore
@@ -0,0 +1 @@
+dropreason_str.c
\ No newline at end of file
diff --git a/net/core/Makefile b/net/core/Makefile
index a8e4f737692b..3c7f99ff6d89 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -4,7 +4,8 @@
 #
 
 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
+	 gen_stats.o gen_estimator.o net_namespace.o secure_seq.o \
+	 flow_dissector.o dropreason_str.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
@@ -39,3 +40,23 @@ 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 <net/dropreason.h>\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 "};\nEXPORT_SYMBOL(drop_reasons);" }' $< > $@
+
+$(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/drop_monitor.c b/net/core/drop_monitor.c
index 41cac0e4834e..4ad1decce724 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -48,19 +48,6 @@
 static int trace_state = TRACE_OFF;
 static bool monitor_hw;
 
-#undef EM
-#undef EMe
-
-#define EM(a, b)	[a] = #b,
-#define EMe(a, b)	[a] = #b
-
-/* drop_reasons is used to translate 'enum skb_drop_reason' to string,
- * which is reported to user space.
- */
-static const char * const drop_reasons[] = {
-	TRACE_SKB_DROP_REASON
-};
-
 /* net_dm_mutex
  *
  * An overall lock guarding every operation coming from userspace.
-- 
2.36.1

[PATCH net-next v2 3/3] net: dropreason: reformat the comment fo skb drop reasons

[menglong8.dong]

From: Menglong Dong <imagedong@tencent.com>

To make the code clear, reformat the comment in dropreason.h to k-doc
style.

Now, the comment can pass the check of kernel-doc without warnning:

$ ./scripts/kernel-doc -v -none include/linux/dropreason.h
include/linux/dropreason.h:7: info: Scanning doc for enum skb_drop_reason

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v2:
- make the comment inline (Jakub Kicinski)
---
 include/net/dropreason.h | 383 +++++++++++++++++++++++----------------
 1 file changed, 227 insertions(+), 156 deletions(-)

diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index 460de425297c..e461a03936f8 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -5,168 +5,239 @@
 
 #include <linux/kernel.h>
 
-/* The reason of skb drop, which is used in kfree_skb_reason().
- * en...maybe they should be splited by group?
+/**
+ * enum skb_drop_reason - the reasons of skb drops
  *
- * Each item here should also be in 'TRACE_SKB_DROP_REASON', which is
- * used to translate the reason to string.
+ * The reason of skb drop, which is used in kfree_skb_reason().
+ * en...maybe they should be splited by group?
  */
 enum skb_drop_reason {
+	/**
+	 * @SKB_NOT_DROPPED_YET: skb is not dropped yet (used for no-drop case)
+	 */
 	SKB_NOT_DROPPED_YET = 0,
-	SKB_DROP_REASON_NOT_SPECIFIED,	/* drop reason is not specified */
-	SKB_DROP_REASON_NO_SOCKET,	/* socket not found */
-	SKB_DROP_REASON_PKT_TOO_SMALL,	/* packet size is too small */
-	SKB_DROP_REASON_TCP_CSUM,	/* TCP checksum error */
-	SKB_DROP_REASON_SOCKET_FILTER,	/* dropped by socket filter */
-	SKB_DROP_REASON_UDP_CSUM,	/* UDP checksum error */
-	SKB_DROP_REASON_NETFILTER_DROP,	/* dropped by netfilter */
-	SKB_DROP_REASON_OTHERHOST,	/* packet don't belong to current
-					 * host (interface is in promisc
-					 * mode)
-					 */
-	SKB_DROP_REASON_IP_CSUM,	/* IP checksum error */
-	SKB_DROP_REASON_IP_INHDR,	/* there is something wrong with
-					 * IP header (see
-					 * IPSTATS_MIB_INHDRERRORS)
-					 */
-	SKB_DROP_REASON_IP_RPFILTER,	/* IP rpfilter validate failed.
-					 * see the document for rp_filter
-					 * in ip-sysctl.rst for more
-					 * information
-					 */
-	SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST, /* destination address of L2
-						  * is multicast, but L3 is
-						  * unicast.
-						  */
-	SKB_DROP_REASON_XFRM_POLICY,	/* xfrm policy check failed */
-	SKB_DROP_REASON_IP_NOPROTO,	/* no support for IP protocol */
-	SKB_DROP_REASON_SOCKET_RCVBUFF,	/* socket receive buff is full */
-	SKB_DROP_REASON_PROTO_MEM,	/* proto memory limition, such as
-					 * udp packet drop out of
-					 * udp_memory_allocated.
-					 */
-	SKB_DROP_REASON_TCP_MD5NOTFOUND,	/* no MD5 hash and one
-						 * expected, corresponding
-						 * to LINUX_MIB_TCPMD5NOTFOUND
-						 */
-	SKB_DROP_REASON_TCP_MD5UNEXPECTED,	/* MD5 hash and we're not
-						 * expecting one, corresponding
-						 * to LINUX_MIB_TCPMD5UNEXPECTED
-						 */
-	SKB_DROP_REASON_TCP_MD5FAILURE,	/* MD5 hash and its wrong,
-					 * corresponding to
-					 * LINUX_MIB_TCPMD5FAILURE
-					 */
-	SKB_DROP_REASON_SOCKET_BACKLOG,	/* failed to add skb to socket
-					 * backlog (see
-					 * LINUX_MIB_TCPBACKLOGDROP)
-					 */
-	SKB_DROP_REASON_TCP_FLAGS,	/* TCP flags invalid */
-	SKB_DROP_REASON_TCP_ZEROWINDOW,	/* TCP receive window size is zero,
-					 * see LINUX_MIB_TCPZEROWINDOWDROP
-					 */
-	SKB_DROP_REASON_TCP_OLD_DATA,	/* the TCP data reveived is already
-					 * received before (spurious retrans
-					 * may happened), see
-					 * LINUX_MIB_DELAYEDACKLOST
-					 */
-	SKB_DROP_REASON_TCP_OVERWINDOW,	/* the TCP data is out of window,
-					 * the seq of the first byte exceed
-					 * the right edges of receive
-					 * window
-					 */
-	SKB_DROP_REASON_TCP_OFOMERGE,	/* the data of skb is already in
-					 * the ofo queue, corresponding to
-					 * LINUX_MIB_TCPOFOMERGE
-					 */
-	SKB_DROP_REASON_TCP_RFC7323_PAWS, /* PAWS check, corresponding to
-					   * LINUX_MIB_PAWSESTABREJECTED
-					   */
-	SKB_DROP_REASON_TCP_INVALID_SEQUENCE, /* Not acceptable SEQ field */
-	SKB_DROP_REASON_TCP_RESET,	/* Invalid RST packet */
-	SKB_DROP_REASON_TCP_INVALID_SYN, /* Incoming packet has unexpected SYN flag */
-	SKB_DROP_REASON_TCP_CLOSE,	/* TCP socket in CLOSE state */
-	SKB_DROP_REASON_TCP_FASTOPEN,	/* dropped by FASTOPEN request socket */
-	SKB_DROP_REASON_TCP_OLD_ACK,	/* TCP ACK is old, but in window */
-	SKB_DROP_REASON_TCP_TOO_OLD_ACK, /* TCP ACK is too old */
-	SKB_DROP_REASON_TCP_ACK_UNSENT_DATA, /* TCP ACK for data we haven't sent yet */
-	SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE, /* pruned from TCP OFO queue */
-	SKB_DROP_REASON_TCP_OFO_DROP,	/* data already in receive queue */
-	SKB_DROP_REASON_IP_OUTNOROUTES,	/* route lookup failed */
-	SKB_DROP_REASON_BPF_CGROUP_EGRESS,	/* dropped by
-						 * BPF_PROG_TYPE_CGROUP_SKB
-						 * eBPF program
-						 */
-	SKB_DROP_REASON_IPV6DISABLED,	/* IPv6 is disabled on the device */
-	SKB_DROP_REASON_NEIGH_CREATEFAIL,	/* failed to create neigh
-						 * entry
-						 */
-	SKB_DROP_REASON_NEIGH_FAILED,	/* neigh entry in failed state */
-	SKB_DROP_REASON_NEIGH_QUEUEFULL,	/* arp_queue for neigh
-						 * entry is full
-						 */
-	SKB_DROP_REASON_NEIGH_DEAD,	/* neigh entry is dead */
-	SKB_DROP_REASON_TC_EGRESS,	/* dropped in TC egress HOOK */
-	SKB_DROP_REASON_QDISC_DROP,	/* dropped by qdisc when packet
-					 * outputting (failed to enqueue to
-					 * current qdisc)
-					 */
-	SKB_DROP_REASON_CPU_BACKLOG,	/* failed to enqueue the skb to
-					 * the per CPU backlog queue. This
-					 * can be caused by backlog queue
-					 * full (see netdev_max_backlog in
-					 * net.rst) or RPS flow limit
-					 */
-	SKB_DROP_REASON_XDP,		/* dropped by XDP in input path */
-	SKB_DROP_REASON_TC_INGRESS,	/* dropped in TC ingress HOOK */
-	SKB_DROP_REASON_UNHANDLED_PROTO,	/* protocol not implemented
-						 * or not supported
-						 */
-	SKB_DROP_REASON_SKB_CSUM,	/* sk_buff checksum computation
-					 * error
-					 */
-	SKB_DROP_REASON_SKB_GSO_SEG,	/* gso segmentation error */
-	SKB_DROP_REASON_SKB_UCOPY_FAULT,	/* failed to copy data from
-						 * user space, e.g., via
-						 * zerocopy_sg_from_iter()
-						 * or skb_orphan_frags_rx()
-						 */
-	SKB_DROP_REASON_DEV_HDR,	/* device driver specific
-					 * header/metadata is invalid
-					 */
-	/* the device is not ready to xmit/recv due to any of its data
-	 * structure that is not up/ready/initialized, e.g., the IFF_UP is
-	 * not set, or driver specific tun->tfiles[txq] is not initialized
+	/** @SKB_DROP_REASON_NOT_SPECIFIED: drop reason is not specified */
+	SKB_DROP_REASON_NOT_SPECIFIED,
+	/** @SKB_DROP_REASON_NO_SOCKET: socket not found */
+	SKB_DROP_REASON_NO_SOCKET,
+	/** @SKB_DROP_REASON_PKT_TOO_SMALL: packet size is too small */
+	SKB_DROP_REASON_PKT_TOO_SMALL,
+	/** @SKB_DROP_REASON_TCP_CSUM: TCP checksum error */
+	SKB_DROP_REASON_TCP_CSUM,
+	/** @SKB_DROP_REASON_SOCKET_FILTER: dropped by socket filter */
+	SKB_DROP_REASON_SOCKET_FILTER,
+	/** @SKB_DROP_REASON_UDP_CSUM: UDP checksum error */
+	SKB_DROP_REASON_UDP_CSUM,
+	/** @SKB_DROP_REASON_NETFILTER_DROP: dropped by netfilter */
+	SKB_DROP_REASON_NETFILTER_DROP,
+	/**
+	 * @SKB_DROP_REASON_OTHERHOST: packet don't belong to current host
+	 * (interface is in promisc mode)
+	 */
+	SKB_DROP_REASON_OTHERHOST,
+	/** @SKB_DROP_REASON_IP_CSUM: IP checksum error */
+	SKB_DROP_REASON_IP_CSUM,
+	/**
+	 * @SKB_DROP_REASON_IP_INHDR: there is something wrong with IP header (see
+	 * IPSTATS_MIB_INHDRERRORS)
+	 */
+	SKB_DROP_REASON_IP_INHDR,
+	/**
+	 * @SKB_DROP_REASON_IP_RPFILTER: IP rpfilter validate failed. see the
+	 * document for rp_filter in ip-sysctl.rst for more information
+	 */
+	SKB_DROP_REASON_IP_RPFILTER,
+	/**
+	 * @SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST: destination address of L2 is
+	 * multicast, but L3 is unicast.
+	 */
+	SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST,
+	/** @SKB_DROP_REASON_XFRM_POLICY: xfrm policy check failed */
+	SKB_DROP_REASON_XFRM_POLICY,
+	/** @SKB_DROP_REASON_IP_NOPROTO: no support for IP protocol */
+	SKB_DROP_REASON_IP_NOPROTO,
+	/** @SKB_DROP_REASON_SOCKET_RCVBUFF: socket receive buff is full */
+	SKB_DROP_REASON_SOCKET_RCVBUFF,
+	/**
+	 * @SKB_DROP_REASON_PROTO_MEM: proto memory limition, such as udp packet
+	 * drop out of udp_memory_allocated.
+	 */
+	SKB_DROP_REASON_PROTO_MEM,
+	/**
+	 * @SKB_DROP_REASON_TCP_MD5NOTFOUND: no MD5 hash and one expected,
+	 * corresponding to LINUX_MIB_TCPMD5NOTFOUND
+	 */
+	SKB_DROP_REASON_TCP_MD5NOTFOUND,
+	/**
+	 * @SKB_DROP_REASON_TCP_MD5UNEXPECTED: MD5 hash and we're not expecting
+	 * one, corresponding to LINUX_MIB_TCPMD5UNEXPECTED
+	 */
+	SKB_DROP_REASON_TCP_MD5UNEXPECTED,
+	/**
+	 * @SKB_DROP_REASON_TCP_MD5FAILURE: MD5 hash and its wrong, corresponding
+	 * to LINUX_MIB_TCPMD5FAILURE
+	 */
+	SKB_DROP_REASON_TCP_MD5FAILURE,
+	/**
+	 * @SKB_DROP_REASON_SOCKET_BACKLOG: failed to add skb to socket backlog (
+	 * see LINUX_MIB_TCPBACKLOGDROP)
+	 */
+	SKB_DROP_REASON_SOCKET_BACKLOG,
+	/** @SKB_DROP_REASON_TCP_FLAGS: TCP flags invalid */
+	SKB_DROP_REASON_TCP_FLAGS,
+	/**
+	 * @SKB_DROP_REASON_TCP_ZEROWINDOW: TCP receive window size is zero,
+	 * see LINUX_MIB_TCPZEROWINDOWDROP
+	 */
+	SKB_DROP_REASON_TCP_ZEROWINDOW,
+	/**
+	 * @SKB_DROP_REASON_TCP_OLD_DATA: the TCP data reveived is already
+	 * received before (spurious retrans may happened), see
+	 * LINUX_MIB_DELAYEDACKLOST
+	 */
+	SKB_DROP_REASON_TCP_OLD_DATA,
+	/**
+	 * @SKB_DROP_REASON_TCP_OVERWINDOW: the TCP data is out of window,
+	 * the seq of the first byte exceed the right edges of receive
+	 * window
+	 */
+	SKB_DROP_REASON_TCP_OVERWINDOW,
+	/**
+	 * @SKB_DROP_REASON_TCP_OFOMERGE: the data of skb is already in the ofo
+	 * queue, corresponding to LINUX_MIB_TCPOFOMERGE
+	 */
+	SKB_DROP_REASON_TCP_OFOMERGE,
+	/**
+	 * @SKB_DROP_REASON_TCP_RFC7323_PAWS: PAWS check, corresponding to
+	 * LINUX_MIB_PAWSESTABREJECTED
+	 */
+	SKB_DROP_REASON_TCP_RFC7323_PAWS,
+	/** @SKB_DROP_REASON_TCP_INVALID_SEQUENCE: Not acceptable SEQ field */
+	SKB_DROP_REASON_TCP_INVALID_SEQUENCE,
+	/** @SKB_DROP_REASON_TCP_RESET: Invalid RST packet */
+	SKB_DROP_REASON_TCP_RESET,
+	/**
+	 * @SKB_DROP_REASON_TCP_INVALID_SYN: Incoming packet has unexpected
+	 * SYN flag
+	 */
+	SKB_DROP_REASON_TCP_INVALID_SYN,
+	/** @SKB_DROP_REASON_TCP_CLOSE: TCP socket in CLOSE state */
+	SKB_DROP_REASON_TCP_CLOSE,
+	/** @SKB_DROP_REASON_TCP_FASTOPEN: dropped by FASTOPEN request socket */
+	SKB_DROP_REASON_TCP_FASTOPEN,
+	/** @SKB_DROP_REASON_TCP_OLD_ACK: TCP ACK is old, but in window */
+	SKB_DROP_REASON_TCP_OLD_ACK,
+	/** @SKB_DROP_REASON_TCP_TOO_OLD_ACK: TCP ACK is too old */
+	SKB_DROP_REASON_TCP_TOO_OLD_ACK,
+	/**
+	 * @SKB_DROP_REASON_TCP_ACK_UNSENT_DATA: TCP ACK for data we haven't
+	 * sent yet
+	 */
+	SKB_DROP_REASON_TCP_ACK_UNSENT_DATA,
+	/** @SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE: pruned from TCP OFO queue */
+	SKB_DROP_REASON_TCP_OFO_QUEUE_PRUNE,
+	/** @SKB_DROP_REASON_TCP_OFO_DROP: data already in receive queue */
+	SKB_DROP_REASON_TCP_OFO_DROP,
+	/** @SKB_DROP_REASON_IP_OUTNOROUTES: route lookup failed */
+	SKB_DROP_REASON_IP_OUTNOROUTES,
+	/**
+	 * @SKB_DROP_REASON_BPF_CGROUP_EGRESS: dropped by BPF_PROG_TYPE_CGROUP_SKB
+	 * eBPF program
+	 */
+	SKB_DROP_REASON_BPF_CGROUP_EGRESS,
+	/** @SKB_DROP_REASON_IPV6DISABLED: IPv6 is disabled on the device */
+	SKB_DROP_REASON_IPV6DISABLED,
+	/** @SKB_DROP_REASON_NEIGH_CREATEFAIL: failed to create neigh entry */
+	SKB_DROP_REASON_NEIGH_CREATEFAIL,
+	/** @SKB_DROP_REASON_NEIGH_FAILED: neigh entry in failed state */
+	SKB_DROP_REASON_NEIGH_FAILED,
+	/** @SKB_DROP_REASON_NEIGH_QUEUEFULL: arp_queue for neigh entry is full */
+	SKB_DROP_REASON_NEIGH_QUEUEFULL,
+	/** @SKB_DROP_REASON_NEIGH_DEAD: neigh entry is dead */
+	SKB_DROP_REASON_NEIGH_DEAD,
+	/** @SKB_DROP_REASON_TC_EGRESS: dropped in TC egress HOOK */
+	SKB_DROP_REASON_TC_EGRESS,
+	/**
+	 * @SKB_DROP_REASON_QDISC_DROP: dropped by qdisc when packet outputting (
+	 * failed to enqueue to current qdisc)
+	 */
+	SKB_DROP_REASON_QDISC_DROP,
+	/**
+	 * @SKB_DROP_REASON_CPU_BACKLOG: failed to enqueue the skb to the per CPU
+	 * backlog queue. This can be caused by backlog queue full (see
+	 * netdev_max_backlog in net.rst) or RPS flow limit
+	 */
+	SKB_DROP_REASON_CPU_BACKLOG,
+	/** @SKB_DROP_REASON_XDP: dropped by XDP in input path */
+	SKB_DROP_REASON_XDP,
+	/** @SKB_DROP_REASON_TC_INGRESS: dropped in TC ingress HOOK */
+	SKB_DROP_REASON_TC_INGRESS,
+	/** @SKB_DROP_REASON_UNHANDLED_PROTO: protocol not implemented or not supported */
+	SKB_DROP_REASON_UNHANDLED_PROTO,
+	/** @SKB_DROP_REASON_SKB_CSUM: sk_buff checksum computation error */
+	SKB_DROP_REASON_SKB_CSUM,
+	/** @SKB_DROP_REASON_SKB_GSO_SEG: gso segmentation error */
+	SKB_DROP_REASON_SKB_GSO_SEG,
+	/**
+	 * @SKB_DROP_REASON_SKB_UCOPY_FAULT: failed to copy data from user space,
+	 * e.g., via zerocopy_sg_from_iter() or skb_orphan_frags_rx()
+	 */
+	SKB_DROP_REASON_SKB_UCOPY_FAULT,
+	/** @SKB_DROP_REASON_DEV_HDR: device driver specific header/metadata is invalid */
+	SKB_DROP_REASON_DEV_HDR,
+	/**
+	 * @SKB_DROP_REASON_DEV_READY: the device is not ready to xmit/recv due to
+	 * any of its data structure that is not up/ready/initialized,
+	 * e.g., the IFF_UP is not set, or driver specific tun->tfiles[txq]
+	 * is not initialized
 	 */
 	SKB_DROP_REASON_DEV_READY,
-	SKB_DROP_REASON_FULL_RING,	/* ring buffer is full */
-	SKB_DROP_REASON_NOMEM,		/* error due to OOM */
-	SKB_DROP_REASON_HDR_TRUNC,      /* failed to trunc/extract the header
-					 * from networking data, e.g., failed
-					 * to pull the protocol header from
-					 * frags via pskb_may_pull()
-					 */
-	SKB_DROP_REASON_TAP_FILTER,     /* dropped by (ebpf) filter directly
-					 * attached to tun/tap, e.g., via
-					 * TUNSETFILTEREBPF
-					 */
-	SKB_DROP_REASON_TAP_TXFILTER,	/* dropped by tx filter implemented
-					 * at tun/tap, e.g., check_filter()
-					 */
-	SKB_DROP_REASON_ICMP_CSUM,	/* ICMP checksum error */
-	SKB_DROP_REASON_INVALID_PROTO,	/* the packet doesn't follow RFC
-					 * 2211, such as a broadcasts
-					 * ICMP_TIMESTAMP
-					 */
-	SKB_DROP_REASON_IP_INADDRERRORS,	/* host unreachable, corresponding
-						 * to IPSTATS_MIB_INADDRERRORS
-						 */
-	SKB_DROP_REASON_IP_INNOROUTES,	/* network unreachable, corresponding
-					 * to IPSTATS_MIB_INADDRERRORS
-					 */
-	SKB_DROP_REASON_PKT_TOO_BIG,	/* packet size is too big (maybe exceed
-					 * the MTU)
-					 */
+	/** @SKB_DROP_REASON_FULL_RING: ring buffer is full */
+	SKB_DROP_REASON_FULL_RING,
+	/** @SKB_DROP_REASON_NOMEM: error due to OOM */
+	SKB_DROP_REASON_NOMEM,
+	/**
+	 * @SKB_DROP_REASON_HDR_TRUNC: failed to trunc/extract the header from
+	 * networking data, e.g., failed to pull the protocol header from
+	 * frags via pskb_may_pull()
+	 */
+	SKB_DROP_REASON_HDR_TRUNC,
+	/**
+	 * @SKB_DROP_REASON_TAP_FILTER: dropped by (ebpf) filter directly attached
+	 * to tun/tap, e.g., via TUNSETFILTEREBPF
+	 */
+	SKB_DROP_REASON_TAP_FILTER,
+	/**
+	 * @SKB_DROP_REASON_TAP_TXFILTER: dropped by tx filter implemented at
+	 * tun/tap, e.g., check_filter()
+	 */
+	SKB_DROP_REASON_TAP_TXFILTER,
+	/** @SKB_DROP_REASON_ICMP_CSUM: ICMP checksum error */
+	SKB_DROP_REASON_ICMP_CSUM,
+	/**
+	 * @SKB_DROP_REASON_INVALID_PROTO: the packet doesn't follow RFC 2211,
+	 * such as a broadcasts ICMP_TIMESTAMP
+	 */
+	SKB_DROP_REASON_INVALID_PROTO,
+	/**
+	 * @SKB_DROP_REASON_IP_INADDRERRORS: host unreachable, corresponding to
+	 * IPSTATS_MIB_INADDRERRORS
+	 */
+	SKB_DROP_REASON_IP_INADDRERRORS,
+	/**
+	 * @SKB_DROP_REASON_IP_INNOROUTES: network unreachable, corresponding to
+	 * IPSTATS_MIB_INADDRERRORS
+	 */
+	SKB_DROP_REASON_IP_INNOROUTES,
+	/**
+	 * @SKB_DROP_REASON_PKT_TOO_BIG: packet size is too big (maybe exceed the
+	 * MTU)
+	 */
+	SKB_DROP_REASON_PKT_TOO_BIG,
+	/**
+	 * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be
+	 * used as a real 'reason'
+	 */
 	SKB_DROP_REASON_MAX,
 };
 
-- 
2.36.1

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[kernel test robot]

Hi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 7e062cda7d90543ac8c7700fc7c5527d0c0f22ad
config: nios2-defconfig (https://download.01.org/0day-ci/archive/20220530/202205301730.inNRSOxX-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
        git checkout 73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
        # save the config file
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 ARCH=nios2 

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[Philip Li]

On Mon, May 30, 2022 at 06:01:36PM +0800, kernel test robot wrote:
> Hi,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on net-next/master]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 7e062cda7d90543ac8c7700fc7c5527d0c0f22ad
> config: nios2-defconfig (https://download.01.org/0day-ci/archive/20220530/202205301730.inNRSOxX-lkp@intel.com/config)
> compiler: nios2-linux-gcc (GCC) 11.3.0
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://github.com/intel-lab-lkp/linux/commit/73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
>         git checkout 73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
>         # save the config file
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 ARCH=nios2 
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All warnings (new ones prefixed by >>):

Kindly ignore this report, the report itself has issue with empty
warnings here. We will check and resolve this.

> 
> -- 
> 0-DAY CI Kernel Test Service
> https://01.org/lkp

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[kernel test robot]

Hi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 7e062cda7d90543ac8c7700fc7c5527d0c0f22ad
config: hexagon-randconfig-r041-20220530 (https://download.01.org/0day-ci/archive/20220530/202205302341.XYygIEYb-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0776c48f9b7e69fa447bee57c7c0985caa856be9)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review menglong8-dong-gmail-com/reorganize-the-code-of-the-enum-skb_drop_reason/20220530-161614
        git checkout 73e3b002fb9086fc734ba4dcc3041f9bb56eb1a2
        # save the config file
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon 

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[Jakub Kicinski]

On Mon, 30 May 2022 16:12:00 +0800 menglong8.dong@gmail.com wrote:
> From: Menglong Dong <imagedong@tencent.com>
> 
> It is annoying to add new skb drop reasons to 'enum skb_drop_reason'
> and TRACE_SKB_DROP_REASON in trace/event/skb.h, and it's easy to forget
> to add the new reasons we added to TRACE_SKB_DROP_REASON.
> 
> TRACE_SKB_DROP_REASON is used to convert drop reason of type number
> to string. For now, the string we passed to user space is exactly the
> same as the name in 'enum skb_drop_reason' with a 'SKB_DROP_REASON_'
> prefix. Therefore, we can use 'auto-generation' to generate these
> drop reasons to string at build time.
> 
> The new header 'dropreason_str.h'

Not any more.

> will be generated, and the
> __DEFINE_SKB_DROP_REASON() in it can do the converting job. Meanwhile,
> we use a global array to store these string, which can be used both
> in drop_monitor and 'kfree_skb' tracepoint.

> diff --git a/include/net/dropreason.h b/include/net/dropreason.h
> index ecd18b7b1364..460de425297c 100644
> --- a/include/net/dropreason.h
> +++ b/include/net/dropreason.h
> @@ -3,6 +3,8 @@
>  #ifndef _LINUX_DROPREASON_H
>  #define _LINUX_DROPREASON_H
>  
> +#include <linux/kernel.h>

Why?

> +dropreason_str.c
> \ No newline at end of file

Heed the warning.

> diff --git a/net/core/Makefile b/net/core/Makefile
> index a8e4f737692b..3c7f99ff6d89 100644
> --- a/net/core/Makefile
> +++ b/net/core/Makefile
> @@ -4,7 +4,8 @@
>  #
>  
>  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
> +	 gen_stats.o gen_estimator.o net_namespace.o secure_seq.o \
> +	 flow_dissector.o dropreason_str.o
>  
>  obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
>  
> @@ -39,3 +40,23 @@ obj-$(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 <net/dropreason.h>\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 "};\nEXPORT_SYMBOL(drop_reasons);" }' $< > $@
> +
> +$(obj)/dropreason_str.c: $(srctree)/include/net/dropreason.h
> +	$(call cmd,dropreason_str)

I'm getting this:

  awk: cmd. line:1: warning: regexp escape sequence `\;' is not a known regexp operator

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[Menglong Dong]

On Tue, May 31, 2022 at 4:13 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Mon, 30 May 2022 16:12:00 +0800 menglong8.dong@gmail.com wrote:
> > From: Menglong Dong <imagedong@tencent.com>
> >
> > It is annoying to add new skb drop reasons to 'enum skb_drop_reason'
> > and TRACE_SKB_DROP_REASON in trace/event/skb.h, and it's easy to forget
> > to add the new reasons we added to TRACE_SKB_DROP_REASON.
> >
> > TRACE_SKB_DROP_REASON is used to convert drop reason of type number
> > to string. For now, the string we passed to user space is exactly the
> > same as the name in 'enum skb_drop_reason' with a 'SKB_DROP_REASON_'
> > prefix. Therefore, we can use 'auto-generation' to generate these
> > drop reasons to string at build time.
> >
> > The new header 'dropreason_str.h'
>
> Not any more.
>
> > will be generated, and the
> > __DEFINE_SKB_DROP_REASON() in it can do the converting job. Meanwhile,
> > we use a global array to store these string, which can be used both
> > in drop_monitor and 'kfree_skb' tracepoint.
>
> > diff --git a/include/net/dropreason.h b/include/net/dropreason.h
> > index ecd18b7b1364..460de425297c 100644
> > --- a/include/net/dropreason.h
> > +++ b/include/net/dropreason.h
> > @@ -3,6 +3,8 @@
> >  #ifndef _LINUX_DROPREASON_H
> >  #define _LINUX_DROPREASON_H
> >
> > +#include <linux/kernel.h>
>
> Why?

Oh, you noticed it. To simplify the code in dropreason_str.c, as
EXPORT_SYMBOL() is used. Okay, I'll move it to the generation
part.

>
> > +dropreason_str.c
> > \ No newline at end of file
>
> Heed the warning.
>
> > diff --git a/net/core/Makefile b/net/core/Makefile
> > index a8e4f737692b..3c7f99ff6d89 100644
> > --- a/net/core/Makefile
> > +++ b/net/core/Makefile
> > @@ -4,7 +4,8 @@
> >  #
> >
> >  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
> > +      gen_stats.o gen_estimator.o net_namespace.o secure_seq.o \
> > +      flow_dissector.o dropreason_str.o
> >
> >  obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
> >
> > @@ -39,3 +40,23 @@ obj-$(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 <net/dropreason.h>\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 "};\nEXPORT_SYMBOL(drop_reasons);" }' $< > $@
> > +
> > +$(obj)/dropreason_str.c: $(srctree)/include/net/dropreason.h
> > +     $(call cmd,dropreason_str)
>
> I'm getting this:
>
>   awk: cmd. line:1: warning: regexp escape sequence `\;' is not a known regexp operator
>

Enn...I think this warning comes from the "/\}\;/ { dr=0; }\" part.
Let me do more investigation.

Thanks!
Menglong Dong

Re: [PATCH net-next v2 2/3] net: skb: use auto-generation to convert skb drop reason to string

[Jakub Kicinski]

On Wed, 1 Jun 2022 11:27:41 +0800 Menglong Dong wrote:
> > > +#include <linux/kernel.h>  
> >
> > Why?  
> 
> Oh, you noticed it. To simplify the code in dropreason_str.c, as
> EXPORT_SYMBOL() is used. Okay, I'll move it to the generation
> part.

IMHO you can move the EXPORT_SYMBOL() to skbuff.c, with a comment
saying that the array itself is in an auto-generated source.
Avoid avoid to "echo" both the EXPORT and the include.