[Intel-wired-lan] [RFC PATCH bpf-next 08/12] xsk: wire upp Tx zero-copy functions
Björn Töpel
bjorn.topel at gmail.com
Tue May 15 19:06:11 UTC 2018
From: Magnus Karlsson <magnus.karlsson at intel.com>
Here we add the functionality required to support zero-copy Tx, and
also exposes various zero-copy related functions to for the netdevs.
Signed-off-by: Magnus Karlsson <magnus.karlsson at intel.com>
---
include/net/xdp_sock.h | 11 +++++++-
net/xdp/xdp_umem.c | 66 ++++++++++++++++++++++++++++++-----------------
net/xdp/xdp_umem.h | 9 +++++--
net/xdp/xsk.c | 69 ++++++++++++++++++++++++++++++++++++++++----------
net/xdp/xsk_queue.h | 32 ++++++++++++++++++++++-
5 files changed, 146 insertions(+), 41 deletions(-)
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 644684eb2caf..6d89fe84674e 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -18,6 +18,7 @@
#include <linux/workqueue.h>
#include <linux/if_xdp.h>
#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <linux/mm.h>
#include <net/sock.h>
@@ -49,6 +50,9 @@ struct xdp_umem {
atomic_t users;
struct work_struct work;
struct net_device *dev;
+ bool zc;
+ spinlock_t xsk_list_lock;
+ struct list_head xsk_list;
u16 queue_id;
};
@@ -61,6 +65,8 @@ struct xdp_sock {
struct list_head flush_node;
u16 queue_id;
struct xsk_queue *tx ____cacheline_aligned_in_smp;
+ struct list_head list;
+ bool zc;
/* Protects multiple processes in the control path */
struct mutex mutex;
u64 rx_dropped;
@@ -73,9 +79,12 @@ int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp);
void xsk_flush(struct xdp_sock *xs);
bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs);
+/* Used from netdev driver */
u32 *xsk_umem_peek_id(struct xdp_umem *umem);
void xsk_umem_discard_id(struct xdp_umem *umem);
-
+void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries);
+bool xsk_umem_consume_tx(struct xdp_umem *umem, dma_addr_t *dma,
+ u32 *len, u16 *offset);
#else
static inline int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
{
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index f70cdaa2ef4d..b904786ac836 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -27,42 +27,49 @@
#define XDP_UMEM_MIN_FRAME_SIZE 2048
int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
- u16 queue_id)
+ u16 queue_id, struct list_head *list_entry)
{
struct netdev_bpf bpf;
+ unsigned long flags;
int err;
if (umem->dev) {
if (dev != umem->dev || queue_id != umem->queue_id)
return -EBUSY;
- return 0;
- }
-
- dev_hold(dev);
- if (dev->netdev_ops->ndo_bpf) {
- bpf.command = XDP_SETUP_XSK_UMEM;
- bpf.xsk.umem = umem;
- bpf.xsk.queue_id = queue_id;
-
- rtnl_lock();
- err = dev->netdev_ops->ndo_bpf(dev, &bpf);
- rtnl_unlock();
-
- if (err) {
+ } else {
+ dev_hold(dev);
+
+ if (dev->netdev_ops->ndo_bpf) {
+ bpf.command = XDP_SETUP_XSK_UMEM;
+ bpf.xsk.umem = umem;
+ bpf.xsk.queue_id = queue_id;
+
+ rtnl_lock();
+ err = dev->netdev_ops->ndo_bpf(dev, &bpf);
+ rtnl_unlock();
+
+ if (err) {
+ dev_put(dev);
+ goto fallback;
+ }
+
+ umem->dev = dev;
+ umem->queue_id = queue_id;
+ umem->zc = true;
+ } else {
dev_put(dev);
- return 0;
}
-
- umem->dev = dev;
- umem->queue_id = queue_id;
- return 0;
}
- dev_put(dev);
+fallback:
+ spin_lock_irqsave(&umem->xsk_list_lock, flags);
+ list_add_rcu(list_entry, &umem->xsk_list);
+ spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
+
return 0;
}
-void xdp_umem_clear_dev(struct xdp_umem *umem)
+static void xdp_umem_clear_dev(struct xdp_umem *umem)
{
struct netdev_bpf bpf;
int err;
@@ -172,11 +179,22 @@ void xdp_get_umem(struct xdp_umem *umem)
atomic_inc(&umem->users);
}
-void xdp_put_umem(struct xdp_umem *umem)
+void xdp_put_umem(struct xdp_umem *umem, struct xdp_sock *xs)
{
+ unsigned long flags;
+
if (!umem)
return;
+ if (xs->dev) {
+ spin_lock_irqsave(&umem->xsk_list_lock, flags);
+ list_del_rcu(&xs->list);
+ spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
+
+ if (umem->zc)
+ synchronize_net();
+ }
+
if (atomic_dec_and_test(&umem->users)) {
INIT_WORK(&umem->work, xdp_umem_release_deferred);
schedule_work(&umem->work);
@@ -297,6 +315,8 @@ int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
umem->npgs = size / PAGE_SIZE;
umem->pgs = NULL;
umem->user = NULL;
+ INIT_LIST_HEAD(&umem->xsk_list);
+ spin_lock_init(&umem->xsk_list_lock);
atomic_set(&umem->users, 1);
diff --git a/net/xdp/xdp_umem.h b/net/xdp/xdp_umem.h
index 3bb96d156b40..5687748a9be3 100644
--- a/net/xdp/xdp_umem.h
+++ b/net/xdp/xdp_umem.h
@@ -22,6 +22,11 @@ static inline char *xdp_umem_get_data(struct xdp_umem *umem, u32 idx)
return umem->frames[idx].addr;
}
+static inline dma_addr_t xdp_umem_get_dma(struct xdp_umem *umem, u32 idx)
+{
+ return umem->frames[idx].dma;
+}
+
static inline char *xdp_umem_get_data_with_headroom(struct xdp_umem *umem,
u32 idx)
{
@@ -31,10 +36,10 @@ static inline char *xdp_umem_get_data_with_headroom(struct xdp_umem *umem,
bool xdp_umem_validate_queues(struct xdp_umem *umem);
int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr);
void xdp_get_umem(struct xdp_umem *umem);
-void xdp_put_umem(struct xdp_umem *umem);
+void xdp_put_umem(struct xdp_umem *umem, struct xdp_sock *xs);
int xdp_umem_create(struct xdp_umem **umem);
int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
- u16 queue_id);
+ u16 queue_id, struct list_head *list_entry);
#endif /* XDP_UMEM_H_ */
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index a0cf9c042ed2..ac979026671f 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -30,6 +30,7 @@
#include <linux/uaccess.h>
#include <linux/net.h>
#include <linux/netdevice.h>
+#include <linux/rculist.h>
#include <net/xdp_sock.h>
#include <net/xdp.h>
@@ -141,6 +142,49 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
return err;
}
+void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries)
+{
+ xskq_produce_flush_id_n(umem->cq, nb_entries);
+}
+EXPORT_SYMBOL(xsk_umem_complete_tx);
+
+bool xsk_umem_consume_tx(struct xdp_umem *umem, dma_addr_t *dma,
+ u32 *len, u16 *offset)
+{
+ struct xdp_desc desc;
+ struct xdp_sock *xs;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
+ if (!xskq_peek_desc(xs->tx, &desc))
+ continue;
+
+ if (xskq_produce_id_lazy(umem->cq, desc.idx))
+ goto out;
+
+ *dma = xdp_umem_get_dma(umem, desc.idx);
+ *len = desc.len;
+ *offset = desc.offset;
+
+ xskq_discard_desc(xs->tx);
+ rcu_read_unlock();
+ return true;
+ }
+
+out:
+ rcu_read_unlock();
+ return false;
+}
+EXPORT_SYMBOL(xsk_umem_consume_tx);
+
+static int xsk_zc_xmit(struct sock *sk)
+{
+ struct xdp_sock *xs = xdp_sk(sk);
+ struct net_device *dev = xs->dev;
+
+ return dev->netdev_ops->ndo_xsk_async_xmit(dev, xs->queue_id);
+}
+
static void xsk_destruct_skb(struct sk_buff *skb)
{
u32 id = (u32)(long)skb_shinfo(skb)->destructor_arg;
@@ -154,7 +198,6 @@ static void xsk_destruct_skb(struct sk_buff *skb)
static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
size_t total_len)
{
- bool need_wait = !(m->msg_flags & MSG_DONTWAIT);
u32 max_batch = TX_BATCH_SIZE;
struct xdp_sock *xs = xdp_sk(sk);
bool sent_frame = false;
@@ -164,8 +207,6 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
if (unlikely(!xs->tx))
return -ENOBUFS;
- if (need_wait)
- return -EOPNOTSUPP;
mutex_lock(&xs->mutex);
@@ -184,12 +225,7 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
}
len = desc.len;
- if (unlikely(len > xs->dev->mtu)) {
- err = -EMSGSIZE;
- goto out;
- }
-
- skb = sock_alloc_send_skb(sk, len, !need_wait, &err);
+ skb = sock_alloc_send_skb(sk, len, 1, &err);
if (unlikely(!skb)) {
err = -EAGAIN;
goto out;
@@ -232,6 +268,7 @@ static int xsk_generic_xmit(struct sock *sk, struct msghdr *m,
static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
{
+ bool need_wait = !(m->msg_flags & MSG_DONTWAIT);
struct sock *sk = sock->sk;
struct xdp_sock *xs = xdp_sk(sk);
@@ -239,8 +276,10 @@ static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
return -ENXIO;
if (unlikely(!(xs->dev->flags & IFF_UP)))
return -ENETDOWN;
+ if (need_wait)
+ return -EOPNOTSUPP;
- return xsk_generic_xmit(sk, m, total_len);
+ return (xs->zc) ? xsk_zc_xmit(sk) : xsk_generic_xmit(sk, m, total_len);
}
static unsigned int xsk_poll(struct file *file, struct socket *sock,
@@ -398,12 +437,14 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
xskq_set_umem(xs->umem->cq, &xs->umem->props);
}
- xs->dev = dev;
- xs->queue_id = sxdp->sxdp_queue_id;
- err = xdp_umem_assign_dev(xs->umem, dev, xs->queue_id);
+ err = xdp_umem_assign_dev(xs->umem, dev, sxdp->sxdp_queue_id,
+ &xs->list);
if (err)
goto out_unlock;
+ xs->dev = dev;
+ xs->zc = xs->umem->zc;
+ xs->queue_id = sxdp->sxdp_queue_id;
xskq_set_umem(xs->rx, &xs->umem->props);
xskq_set_umem(xs->tx, &xs->umem->props);
@@ -612,7 +653,7 @@ static void xsk_destruct(struct sock *sk)
xskq_destroy(xs->rx);
xskq_destroy(xs->tx);
- xdp_put_umem(xs->umem);
+ xdp_put_umem(xs->umem, xs);
sk_refcnt_debug_dec(sk);
}
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 599a8d43c69a..5533bf32a254 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -17,9 +17,11 @@
#include <linux/types.h>
#include <linux/if_xdp.h>
+#include <linux/cache.h>
#include <net/xdp_sock.h>
#define RX_BATCH_SIZE 16
+#define LAZY_UPDATE_THRESHOLD 128
struct xsk_queue {
struct xdp_umem_props umem_props;
@@ -53,9 +55,14 @@ 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 = q->nentries - (producer - q->cons_tail);
+ u32 free_entries = xskq_nb_free_lazy(q, producer);
if (free_entries >= dcnt)
return free_entries;
@@ -119,6 +126,9 @@ static inline int xskq_produce_id(struct xsk_queue *q, u32 id)
{
struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+ if (xskq_nb_free(q, q->prod_tail, LAZY_UPDATE_THRESHOLD) == 0)
+ return -ENOSPC;
+
ring->desc[q->prod_tail++ & q->ring_mask] = id;
/* Order producer and data */
@@ -128,6 +138,26 @@ static inline int xskq_produce_id(struct xsk_queue *q, u32 id)
return 0;
}
+static inline int xskq_produce_id_lazy(struct xsk_queue *q, u32 id)
+{
+ struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;
+
+ if (xskq_nb_free(q, q->prod_head, LAZY_UPDATE_THRESHOLD) == 0)
+ return -ENOSPC;
+
+ ring->desc[q->prod_head++ & q->ring_mask] = id;
+ return 0;
+}
+
+static inline void xskq_produce_flush_id_n(struct xsk_queue *q, u32 nb_entries)
+{
+ /* Order producer and data */
+ smp_wmb();
+
+ q->prod_tail += nb_entries;
+ WRITE_ONCE(q->ring->producer, q->prod_tail);
+}
+
static inline int xskq_reserve_id(struct xsk_queue *q)
{
if (xskq_nb_free(q, q->prod_head, 1) == 0)
--
2.14.1
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