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Commit 39d393cf authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'af_xdp-fixes' 



Magnus Karlsson says:

====================
This patch set fixes three bugs in the SKB TX path of AF_XDP.
Details in the individual commits.

The structure of the patch set is as follows:

Patch 1: Fix for lost completion message
Patch 2-3: Fix for possible multiple completions of single packet
Patch 4: Fix potential race during error

Changes from v1:

* Added explanation of race in commit message of patch 4.
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents d0fbad0a a9744f7c

include/net/xdp_sock.h

+4 −0
Original line number Diff line number Diff line
@@ -60,6 +60,10 @@ struct xdp_sock { 
	bool zc;

	/* Protects multiple processes in the control path */

	struct mutex mutex;

	/* Mutual exclusion of NAPI TX thread and sendmsg error paths

	 * in the SKB destructor callback.

	 */

	spinlock_t tx_completion_lock;

	u64 rx_dropped;

};

net/xdp/xsk.c

+7 −3
Original line number Diff line number Diff line
@@ -199,8 +199,11 @@ static void xsk_destruct_skb(struct sk_buff *skb) 
{

	u64 addr = (u64)(long)skb_shinfo(skb)->destructor_arg;

	struct xdp_sock *xs = xdp_sk(skb->sk);

	unsigned long flags;



	spin_lock_irqsave(&xs->tx_completion_lock, flags);

	WARN_ON_ONCE(xskq_produce_addr(xs->umem->cq, addr));

	spin_unlock_irqrestore(&xs->tx_completion_lock, flags);



	sock_wfree(skb);

}
@@ -268,15 +271,15 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m, 
		skb->destructor = xsk_destruct_skb;



		err = dev_direct_xmit(skb, xs->queue_id);

		xskq_discard_desc(xs->tx);

		/* Ignore NET_XMIT_CN as packet might have been sent */

		if (err == NET_XMIT_DROP || err == NETDEV_TX_BUSY) {

			err = -EAGAIN;

			/* SKB consumed by dev_direct_xmit() */

			/* SKB completed but not sent */

			err = -EBUSY;

			goto out;

		}



		sent_frame = true;

		xskq_discard_desc(xs->tx);

	}



out:
@@ -755,6 +758,7 @@ static int xsk_create(struct net *net, struct socket *sock, int protocol, 


	xs = xdp_sk(sk);

	mutex_init(&xs->mutex);

	spin_lock_init(&xs->tx_completion_lock);



	local_bh_disable();

	sock_prot_inuse_add(net, &xsk_proto, 1);

net/xdp/xsk_queue.h

+2 −7
Original line number Diff line number Diff line
@@ -62,14 +62,9 @@ static inline u32 xskq_nb_avail(struct xsk_queue *q, u32 dcnt) 
	return (entries > dcnt) ? dcnt : entries;

}



static inline u32 xskq_nb_free_lazy(struct xsk_queue *q, u32 producer)

{

	return q->nentries - (producer - q->cons_tail);

}



static inline u32 xskq_nb_free(struct xsk_queue *q, u32 producer, u32 dcnt)

{

	u32 free_entries = xskq_nb_free_lazy(q, producer);

	u32 free_entries = q->nentries - (producer - q->cons_tail);



	if (free_entries >= dcnt)

		return free_entries;
@@ -129,7 +124,7 @@ static inline int xskq_produce_addr(struct xsk_queue *q, u64 addr) 
{

	struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;



	if (xskq_nb_free(q, q->prod_tail, LAZY_UPDATE_THRESHOLD) == 0)

	if (xskq_nb_free(q, q->prod_tail, 1) == 0)

		return -ENOSPC;



	ring->desc[q->prod_tail++ & q->ring_mask] = addr;

samples/bpf/xdpsock_user.c

+1 −1
Original line number Diff line number Diff line
@@ -729,7 +729,7 @@ static void kick_tx(int fd) 
	int ret;



	ret = sendto(fd, NULL, 0, MSG_DONTWAIT, NULL, 0);

	if (ret >= 0 || errno == ENOBUFS || errno == EAGAIN)

	if (ret >= 0 || errno == ENOBUFS || errno == EAGAIN || errno == EBUSY)

		return;

	lassert(0);

}