Commit 4c22aac3 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tuntap-kfree_skb_reason' 



Dongli Zhang says:

====================
tun/tap: use kfree_skb_reason() to trace dropped skb

The commit c504e5c2 ("net: skb: introduce kfree_skb_reason()") has
introduced the kfree_skb_reason() to help track the reason.

The tun and tap are commonly used as virtio-net/vhost-net backend. This is to
use kfree_skb_reason() to trace the dropped skb for those two drivers.

Changed since v1:
- I have renamed many of the reasons since v1. I make them as generic as
  possible so that they can be re-used by core networking and drivers.

Changed since v2:
- declare drop_reason as type "enum skb_drop_reason"
- handle the drop in skb_list_walk_safe() case for tap driver, and
  kfree_skb_list_reason() is introduced

Changed since v3 (only for PATCH 4/4):
- rename to TAP_FILTER and TAP_TXFILTER
- honor reverse xmas tree style declaration for 'drop_reason' in
  tun_net_xmit()

Changed since v4:
- make kfree_skb_list() static inline
- add 'computation' to SKB_CSUM comment
- change COPY_DATA to UCOPY_FAULT
- add 'metadata' to DEV_HDR comment
- expand comment on DEV_READY
- change SKB_TRIM to NOMEM
- chnage SKB_PULL to HDR_TRUNC
Changed since v5:
- rebase to net-next

The following reasons are introduced.

- SKB_DROP_REASON_SKB_CSUM
- SKB_DROP_REASON_SKB_GSO_SEG
- SKB_DROP_REASON_SKB_UCOPY_FAULT
- SKB_DROP_REASON_DEV_HDR
- SKB_DROP_REASON_FULL_RING
- SKB_DROP_REASON_DEV_READY
- SKB_DROP_REASON_NOMEM
- SKB_DROP_REASON_HDR_TRUNC
- SKB_DROP_REASON_TAP_FILTER
- SKB_DROP_REASON_TAP_TXFILTER

This is the output for TUN device.

          <idle>-0       [029] ..s1.   450.727651: kfree_skb: skbaddr=0000000023d235cc protocol=0 location=00000000a6748854 reason: NOT_SPECIFIED
          <idle>-0       [000] b.s3.   451.165671: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   453.149650: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   455.133576: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   457.117566: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING

This is the output for TAP device.

          arping-7053    [006] ..s1.  1000.047753: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          <idle>-0       [022] ..s1.  1000.778514: kfree_skb: skbaddr=000000002c1e706c protocol=0 location=00000000a6748854 reason: NOT_SPECIFIED
          arping-7053    [006] ..s1.  1001.047830: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          arping-7053    [006] ..s1.  1002.047918: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          arping-7053    [006] ..s1.  1003.048017: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 925a2421 4b4f052e

drivers/net/tap.c

+25 −10
Original line number Diff line number Diff line
@@ -322,6 +322,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
	struct tap_dev *tap;

	struct tap_queue *q;

	netdev_features_t features = TAP_FEATURES;

	enum skb_drop_reason drop_reason;



	tap = tap_dev_get_rcu(dev);

	if (!tap)
@@ -343,12 +344,16 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
		struct sk_buff *segs = __skb_gso_segment(skb, features, false);

		struct sk_buff *next;



		if (IS_ERR(segs))

		if (IS_ERR(segs)) {

			drop_reason = SKB_DROP_REASON_SKB_GSO_SEG;

			goto drop;

		}



		if (!segs) {

			if (ptr_ring_produce(&q->ring, skb))

			if (ptr_ring_produce(&q->ring, skb)) {

				drop_reason = SKB_DROP_REASON_FULL_RING;

				goto drop;

			}

			goto wake_up;

		}
@@ -356,8 +361,9 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
		skb_list_walk_safe(segs, skb, next) {

			skb_mark_not_on_list(skb);

			if (ptr_ring_produce(&q->ring, skb)) {

				kfree_skb(skb);

				kfree_skb_list(next);

				drop_reason = SKB_DROP_REASON_FULL_RING;

				kfree_skb_reason(skb, drop_reason);

				kfree_skb_list_reason(next, drop_reason);

				break;

			}

		}
@@ -369,11 +375,15 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
		 */

		if (skb->ip_summed == CHECKSUM_PARTIAL &&

		    !(features & NETIF_F_CSUM_MASK) &&

		    skb_checksum_help(skb))

		    skb_checksum_help(skb)) {

			drop_reason = SKB_DROP_REASON_SKB_CSUM;

			goto drop;

		if (ptr_ring_produce(&q->ring, skb))

		}

		if (ptr_ring_produce(&q->ring, skb)) {

			drop_reason = SKB_DROP_REASON_FULL_RING;

			goto drop;

		}

	}



wake_up:

	wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
@@ -383,7 +393,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb) 
	/* Count errors/drops only here, thus don't care about args. */

	if (tap->count_rx_dropped)

		tap->count_rx_dropped(tap);

	kfree_skb(skb);

	kfree_skb_reason(skb, drop_reason);

	return RX_HANDLER_CONSUMED;

}

EXPORT_SYMBOL_GPL(tap_handle_frame);
@@ -632,6 +642,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 
	int depth;

	bool zerocopy = false;

	size_t linear;

	enum skb_drop_reason drop_reason;



	if (q->flags & IFF_VNET_HDR) {

		vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
@@ -696,8 +707,10 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 
	else

		err = skb_copy_datagram_from_iter(skb, 0, from, len);



	if (err)

	if (err) {

		drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;

		goto err_kfree;

	}



	skb_set_network_header(skb, ETH_HLEN);

	skb_reset_mac_header(skb);
@@ -706,9 +719,11 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 
	if (vnet_hdr_len) {

		err = virtio_net_hdr_to_skb(skb, &vnet_hdr,

					    tap_is_little_endian(q));

		if (err)

		if (err) {

			drop_reason = SKB_DROP_REASON_DEV_HDR;

			goto err_kfree;

		}

	}



	skb_probe_transport_header(skb);
@@ -738,7 +753,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, 
	return total_len;



err_kfree:

	kfree_skb(skb);

	kfree_skb_reason(skb, drop_reason);



err:

	rcu_read_lock();

drivers/net/tun.c

+30 −8
Original line number Diff line number Diff line
@@ -1058,6 +1058,7 @@ static unsigned int run_ebpf_filter(struct tun_struct *tun, 
static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)

{

	struct tun_struct *tun = netdev_priv(dev);

	enum skb_drop_reason drop_reason;

	int txq = skb->queue_mapping;

	struct netdev_queue *queue;

	struct tun_file *tfile;
@@ -1067,8 +1068,10 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) 
	tfile = rcu_dereference(tun->tfiles[txq]);



	/* Drop packet if interface is not attached */

	if (!tfile)

	if (!tfile) {

		drop_reason = SKB_DROP_REASON_DEV_READY;

		goto drop;

	}



	if (!rcu_dereference(tun->steering_prog))

		tun_automq_xmit(tun, skb);
@@ -1078,19 +1081,32 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) 
	/* Drop if the filter does not like it.

	 * This is a noop if the filter is disabled.

	 * Filter can be enabled only for the TAP devices. */

	if (!check_filter(&tun->txflt, skb))

	if (!check_filter(&tun->txflt, skb)) {

		drop_reason = SKB_DROP_REASON_TAP_TXFILTER;

		goto drop;

	}



	if (tfile->socket.sk->sk_filter &&

	    sk_filter(tfile->socket.sk, skb))

	    sk_filter(tfile->socket.sk, skb)) {

		drop_reason = SKB_DROP_REASON_SOCKET_FILTER;

		goto drop;

	}



	len = run_ebpf_filter(tun, skb, len);

	if (len == 0 || pskb_trim(skb, len))

	if (len == 0) {

		drop_reason = SKB_DROP_REASON_TAP_FILTER;

		goto drop;

	}



	if (pskb_trim(skb, len)) {

		drop_reason = SKB_DROP_REASON_NOMEM;

		goto drop;

	}



	if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC)))

	if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) {

		drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;

		goto drop;

	}



	skb_tx_timestamp(skb);
@@ -1101,8 +1117,10 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) 


	nf_reset_ct(skb);



	if (ptr_ring_produce(&tfile->tx_ring, skb))

	if (ptr_ring_produce(&tfile->tx_ring, skb)) {

		drop_reason = SKB_DROP_REASON_FULL_RING;

		goto drop;

	}



	/* NETIF_F_LLTX requires to do our own update of trans_start */

	queue = netdev_get_tx_queue(dev, txq);
@@ -1119,7 +1137,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) 
drop:

	atomic_long_inc(&dev->tx_dropped);

	skb_tx_error(skb);

	kfree_skb(skb);

	kfree_skb_reason(skb, drop_reason);

	rcu_read_unlock();

	return NET_XMIT_DROP;

}
@@ -1717,6 +1735,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	u32 rxhash = 0;

	int skb_xdp = 1;

	bool frags = tun_napi_frags_enabled(tfile);

	enum skb_drop_reason drop_reason;



	if (!(tun->flags & IFF_NO_PI)) {

		if (len < sizeof(pi))
@@ -1820,9 +1839,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 


		if (err) {

			err = -EFAULT;

			drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;

drop:

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

			kfree_skb(skb);

			kfree_skb_reason(skb, drop_reason);

			if (frags) {

				tfile->napi.skb = NULL;

				mutex_unlock(&tfile->napi_mutex);
@@ -1869,6 +1889,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	case IFF_TAP:

		if (frags && !pskb_may_pull(skb, ETH_HLEN)) {

			err = -ENOMEM;

			drop_reason = SKB_DROP_REASON_HDR_TRUNC;

			goto drop;

		}

		skb->protocol = eth_type_trans(skb, tun->dev);
@@ -1922,6 +1943,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, 
	if (unlikely(!(tun->dev->flags & IFF_UP))) {

		err = -EIO;

		rcu_read_unlock();

		drop_reason = SKB_DROP_REASON_DEV_READY;

		goto drop;

	}

include/linux/skbuff.h

+31 −0
Original line number Diff line number Diff line
@@ -412,6 +412,37 @@ enum skb_drop_reason { 
					 * this means that L3 protocol is

					 * 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_MAX,

};

include/trace/events/skb.h

+10 −0
Original line number Diff line number Diff line
@@ -51,6 +51,16 @@ 
	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_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)		\

	EMe(SKB_DROP_REASON_MAX, MAX)



#undef EM