Commit 6af3b428 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'skb-drop-reasons' 



Menglong Dong says:

====================
net: dev: add skb drop reasons to net/core/dev.c

In the commit c504e5c2 ("net: skb: introduce kfree_skb_reason()"),
we added the support of reporting the reasons of skb drops to kfree_skb
tracepoint. And in this series patches, reasons for skb drops are added
to the link layer, which means that 'net/core/dev.c' is our target.

Following functions are processed:

sch_handle_egress()
__dev_xmit_skb()
enqueue_to_backlog()
do_xdp_generic()
sch_handle_ingress()
__netif_receive_skb_core()

and following new drop reasons are added (what they mean can be see in
the document of them):

SKB_DROP_REASON_QDISC_EGRESS
SKB_DROP_REASON_QDISC_DROP
SKB_DROP_REASON_CPU_BACKLOG
SKB_DROP_REASON_XDP
SKB_DROP_REASON_QDISC_INGRESS
SKB_DROP_REASON_PTYPE_ABSENT

In order to add skb drop reasons to kfree_skb_list(), the function
kfree_skb_list_reason() is introduced in the 2th patch, which will be
used in __dev_xmit_skb() in the 3th patch.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 9f9919f7 6c2728b7

include/linux/skbuff.h

+25 −1
Original line number Diff line number Diff line
@@ -394,6 +394,24 @@ enum skb_drop_reason { 
						 * 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_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_MAX,

};
@@ -1201,10 +1219,16 @@ static inline void kfree_skb(struct sk_buff *skb) 
}



void skb_release_head_state(struct sk_buff *skb);

void kfree_skb_list(struct sk_buff *segs);

void kfree_skb_list_reason(struct sk_buff *segs,

			   enum skb_drop_reason reason);

void skb_dump(const char *level, const struct sk_buff *skb, bool full_pkt);

void skb_tx_error(struct sk_buff *skb);



static inline void kfree_skb_list(struct sk_buff *segs)

{

	kfree_skb_list_reason(segs, SKB_DROP_REASON_NOT_SPECIFIED);

}



#ifdef CONFIG_TRACEPOINTS

void consume_skb(struct sk_buff *skb);

#else

include/trace/events/skb.h

+6 −0
Original line number Diff line number Diff line
@@ -45,6 +45,12 @@ 
	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_PTYPE_ABSENT, PTYPE_ABSENT)		\

	EMe(SKB_DROP_REASON_MAX, MAX)



#undef EM

net/core/dev.c

+15 −9
Original line number Diff line number Diff line
@@ -3759,7 +3759,8 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, 


no_lock_out:

		if (unlikely(to_free))

			kfree_skb_list(to_free);

			kfree_skb_list_reason(to_free,

					      SKB_DROP_REASON_QDISC_DROP);

		return rc;

	}
@@ -3814,7 +3815,7 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, 
	}

	spin_unlock(root_lock);

	if (unlikely(to_free))

		kfree_skb_list(to_free);

		kfree_skb_list_reason(to_free, SKB_DROP_REASON_QDISC_DROP);

	if (unlikely(contended))

		spin_unlock(&q->busylock);

	return rc;
@@ -3889,7 +3890,7 @@ sch_handle_egress(struct sk_buff *skb, int *ret, struct net_device *dev) 
	case TC_ACT_SHOT:

		mini_qdisc_qstats_cpu_drop(miniq);

		*ret = NET_XMIT_DROP;

		kfree_skb(skb);

		kfree_skb_reason(skb, SKB_DROP_REASON_TC_EGRESS);

		return NULL;

	case TC_ACT_STOLEN:

	case TC_ACT_QUEUED:
@@ -4569,10 +4570,12 @@ static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen) 
static int enqueue_to_backlog(struct sk_buff *skb, int cpu,

			      unsigned int *qtail)

{

	enum skb_drop_reason reason;

	struct softnet_data *sd;

	unsigned long flags;

	unsigned int qlen;



	reason = SKB_DROP_REASON_NOT_SPECIFIED;

	sd = &per_cpu(softnet_data, cpu);



	rps_lock_irqsave(sd, &flags);
@@ -4595,13 +4598,14 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu, 
			napi_schedule_rps(sd);

		goto enqueue;

	}

	reason = SKB_DROP_REASON_CPU_BACKLOG;



drop:

	sd->dropped++;

	rps_unlock_irq_restore(sd, &flags);



	atomic_long_inc(&skb->dev->rx_dropped);

	kfree_skb(skb);

	kfree_skb_reason(skb, reason);

	return NET_RX_DROP;

}
@@ -4821,7 +4825,7 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb) 
	}

	return XDP_PASS;

out_redir:

	kfree_skb(skb);

	kfree_skb_reason(skb, SKB_DROP_REASON_XDP);

	return XDP_DROP;

}

EXPORT_SYMBOL_GPL(do_xdp_generic);
@@ -5037,7 +5041,7 @@ sch_handle_ingress(struct sk_buff *skb, struct packet_type **pt_prev, int *ret, 
		break;

	case TC_ACT_SHOT:

		mini_qdisc_qstats_cpu_drop(miniq);

		kfree_skb(skb);

		kfree_skb_reason(skb, SKB_DROP_REASON_TC_INGRESS);

		return NULL;

	case TC_ACT_STOLEN:

	case TC_ACT_QUEUED:
@@ -5354,11 +5358,13 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc, 
		*ppt_prev = pt_prev;

	} else {

drop:

		if (!deliver_exact)

		if (!deliver_exact) {

			atomic_long_inc(&skb->dev->rx_dropped);

		else

			kfree_skb_reason(skb, SKB_DROP_REASON_PTYPE_ABSENT);

		} else {

			atomic_long_inc(&skb->dev->rx_nohandler);

			kfree_skb(skb);

		}

		/* Jamal, now you will not able to escape explaining

		 * me how you were going to use this. :-)

		 */

net/core/skbuff.c

+4 −3
Original line number Diff line number Diff line
@@ -777,16 +777,17 @@ void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason) 
}

EXPORT_SYMBOL(kfree_skb_reason);



void kfree_skb_list(struct sk_buff *segs)

void kfree_skb_list_reason(struct sk_buff *segs,

			   enum skb_drop_reason reason)

{

	while (segs) {

		struct sk_buff *next = segs->next;



		kfree_skb(segs);

		kfree_skb_reason(segs, reason);

		segs = next;

	}

}

EXPORT_SYMBOL(kfree_skb_list);

EXPORT_SYMBOL(kfree_skb_list_reason);



/* Dump skb information and contents.

 *