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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: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2018-07-02 18:37:12 -07:00
parent d0fbad0aec a9744f7ca2
commit 39d393cf20
4 changed files with 14 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/net/xdp_sock.h
View File

@ -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;
};

10
net/xdp/xsk.c
View File

@ -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);

9
net/xdp/xsk_queue.h
View File

@ -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;

2
samples/bpf/xdpsock_user.c
View File

@ -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);
}