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xsk: fix immature cq descriptor production #5874

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xsk: fix immature cq descriptor production #5874

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112 changes: 98 additions & 14 deletions net/xdp/xsk.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,20 @@
#define TX_BATCH_SIZE 32
#define MAX_PER_SOCKET_BUDGET 32

struct xsk_addr_node {
u64 addr;
struct list_head addr_node;
};

struct xsk_addr_head {
u32 num_descs;
struct list_head addrs_list;
};

static struct kmem_cache *xsk_tx_generic_cache;

#define XSKCB(skb) ((struct xsk_addr_head *)((skb)->cb))

void xsk_set_rx_need_wakeup(struct xsk_buff_pool *pool)
{
if (pool->cached_need_wakeup & XDP_WAKEUP_RX)
Expand Down Expand Up @@ -532,24 +546,42 @@ static int xsk_wakeup(struct xdp_sock *xs, u8 flags)
return dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, flags);
}

static int xsk_cq_reserve_addr_locked(struct xsk_buff_pool *pool, u64 addr)
static int xsk_cq_reserve_locked(struct xsk_buff_pool *pool)
{
unsigned long flags;
int ret;

spin_lock_irqsave(&pool->cq_lock, flags);
ret = xskq_prod_reserve_addr(pool->cq, addr);
ret = xskq_prod_reserve(pool->cq);
spin_unlock_irqrestore(&pool->cq_lock, flags);

return ret;
}

static void xsk_cq_submit_locked(struct xsk_buff_pool *pool, u32 n)
static void xsk_cq_submit_addr_locked(struct xsk_buff_pool *pool,
struct sk_buff *skb)
{
struct xsk_addr_node *pos, *tmp;
u32 descs_processed = 0;
unsigned long flags;
u32 idx;

spin_lock_irqsave(&pool->cq_lock, flags);
xskq_prod_submit_n(pool->cq, n);
idx = xskq_get_prod(pool->cq);

xskq_prod_write_addr(pool->cq, idx, (u64)skb_shinfo(skb)->destructor_arg);
descs_processed++;

if (unlikely(XSKCB(skb)->num_descs > 1)) {
list_for_each_entry_safe(pos, tmp, &XSKCB(skb)->addrs_list, addr_node) {
xskq_prod_write_addr(pool->cq, idx + descs_processed,
pos->addr);
descs_processed++;
list_del(&pos->addr_node);
kmem_cache_free(xsk_tx_generic_cache, pos);
}
}
xskq_prod_submit_n(pool->cq, descs_processed);
spin_unlock_irqrestore(&pool->cq_lock, flags);
}

Expand All @@ -562,9 +594,14 @@ static void xsk_cq_cancel_locked(struct xsk_buff_pool *pool, u32 n)
spin_unlock_irqrestore(&pool->cq_lock, flags);
}

static void xsk_inc_num_desc(struct sk_buff *skb)
{
XSKCB(skb)->num_descs++;
}

static u32 xsk_get_num_desc(struct sk_buff *skb)
{
return skb ? (long)skb_shinfo(skb)->destructor_arg : 0;
return XSKCB(skb)->num_descs;
}

static void xsk_destruct_skb(struct sk_buff *skb)
Expand All @@ -576,23 +613,33 @@ static void xsk_destruct_skb(struct sk_buff *skb)
*compl->tx_timestamp = ktime_get_tai_fast_ns();
}

xsk_cq_submit_locked(xdp_sk(skb->sk)->pool, xsk_get_num_desc(skb));
xsk_cq_submit_addr_locked(xdp_sk(skb->sk)->pool, skb);
sock_wfree(skb);
}

static void xsk_set_destructor_arg(struct sk_buff *skb)
static void xsk_set_destructor_arg(struct sk_buff *skb, u64 addr)
{
long num = xsk_get_num_desc(xdp_sk(skb->sk)->skb) + 1;

skb_shinfo(skb)->destructor_arg = (void *)num;
BUILD_BUG_ON(sizeof(struct xsk_addr_head) > sizeof(skb->cb));
INIT_LIST_HEAD(&XSKCB(skb)->addrs_list);
XSKCB(skb)->num_descs = 0;
skb_shinfo(skb)->destructor_arg = (void *)addr;
}

static void xsk_consume_skb(struct sk_buff *skb)
{
struct xdp_sock *xs = xdp_sk(skb->sk);
u32 num_descs = xsk_get_num_desc(skb);
struct xsk_addr_node *pos, *tmp;

if (unlikely(num_descs > 1)) {
list_for_each_entry_safe(pos, tmp, &XSKCB(skb)->addrs_list, addr_node) {
list_del(&pos->addr_node);
kmem_cache_free(xsk_tx_generic_cache, pos);
}
}

skb->destructor = sock_wfree;
xsk_cq_cancel_locked(xs->pool, xsk_get_num_desc(skb));
xsk_cq_cancel_locked(xs->pool, num_descs);
/* Free skb without triggering the perf drop trace */
consume_skb(skb);
xs->skb = NULL;
Expand All @@ -609,6 +656,7 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs,
{
struct xsk_buff_pool *pool = xs->pool;
u32 hr, len, ts, offset, copy, copied;
struct xsk_addr_node *xsk_addr;
struct sk_buff *skb = xs->skb;
struct page *page;
void *buffer;
Expand All @@ -623,6 +671,19 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs,
return ERR_PTR(err);

skb_reserve(skb, hr);

xsk_set_destructor_arg(skb, desc->addr);
} else {
xsk_addr = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL);
if (!xsk_addr)
return ERR_PTR(-ENOMEM);

/* in case of -EOVERFLOW that could happen below,
* xsk_consume_skb() will release this node as whole skb
* would be dropped, which implies freeing all list elements
*/
xsk_addr->addr = desc->addr;
list_add_tail(&xsk_addr->addr_node, &XSKCB(skb)->addrs_list);
}

addr = desc->addr;
Expand Down Expand Up @@ -694,8 +755,11 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
err = skb_store_bits(skb, 0, buffer, len);
if (unlikely(err))
goto free_err;

xsk_set_destructor_arg(skb, desc->addr);
} else {
int nr_frags = skb_shinfo(skb)->nr_frags;
struct xsk_addr_node *xsk_addr;
struct page *page;
u8 *vaddr;

Expand All @@ -710,12 +774,22 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
goto free_err;
}

xsk_addr = kmem_cache_zalloc(xsk_tx_generic_cache, GFP_KERNEL);
if (!xsk_addr) {
__free_page(page);
err = -ENOMEM;
goto free_err;
}

vaddr = kmap_local_page(page);
memcpy(vaddr, buffer, len);
kunmap_local(vaddr);

skb_add_rx_frag(skb, nr_frags, page, 0, len, PAGE_SIZE);
refcount_add(PAGE_SIZE, &xs->sk.sk_wmem_alloc);

xsk_addr->addr = desc->addr;
list_add_tail(&xsk_addr->addr_node, &XSKCB(skb)->addrs_list);
}

if (first_frag && desc->options & XDP_TX_METADATA) {
Expand Down Expand Up @@ -759,7 +833,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,
skb->mark = READ_ONCE(xs->sk.sk_mark);
skb->destructor = xsk_destruct_skb;
xsk_tx_metadata_to_compl(meta, &skb_shinfo(skb)->xsk_meta);
xsk_set_destructor_arg(skb);
xsk_inc_num_desc(skb);

return skb;

Expand All @@ -769,7 +843,7 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs,

if (err == -EOVERFLOW) {
/* Drop the packet */
xsk_set_destructor_arg(xs->skb);
xsk_inc_num_desc(xs->skb);
xsk_drop_skb(xs->skb);
xskq_cons_release(xs->tx);
} else {
Expand Down Expand Up @@ -812,7 +886,7 @@ static int __xsk_generic_xmit(struct sock *sk)
* if there is space in it. This avoids having to implement
* any buffering in the Tx path.
*/
err = xsk_cq_reserve_addr_locked(xs->pool, desc.addr);
err = xsk_cq_reserve_locked(xs->pool);
if (err) {
err = -EAGAIN;
goto out;
Expand Down Expand Up @@ -1815,8 +1889,18 @@ static int __init xsk_init(void)
if (err)
goto out_pernet;

xsk_tx_generic_cache = kmem_cache_create("xsk_generic_xmit_cache",
sizeof(struct xsk_addr_node),
0, SLAB_HWCACHE_ALIGN, NULL);
if (!xsk_tx_generic_cache) {
err = -ENOMEM;
goto out_unreg_notif;
}

return 0;

out_unreg_notif:
unregister_netdevice_notifier(&xsk_netdev_notifier);
out_pernet:
unregister_pernet_subsys(&xsk_net_ops);
out_sk:
Expand Down
12 changes: 12 additions & 0 deletions net/xdp/xsk_queue.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -344,6 +344,11 @@ static inline u32 xskq_cons_present_entries(struct xsk_queue *q)

/* Functions for producers */

static inline u32 xskq_get_prod(struct xsk_queue *q)
{
return READ_ONCE(q->ring->producer);
}

static inline u32 xskq_prod_nb_free(struct xsk_queue *q, u32 max)
{
u32 free_entries = q->nentries - (q->cached_prod - q->cached_cons);
Expand Down Expand Up @@ -390,6 +395,13 @@ static inline int xskq_prod_reserve_addr(struct xsk_queue *q, u64 addr)
return 0;
}

static inline void xskq_prod_write_addr(struct xsk_queue *q, u32 idx, u64 addr)
{
struct xdp_umem_ring *ring = (struct xdp_umem_ring *)q->ring;

ring->desc[idx & q->ring_mask] = addr;
}

static inline void xskq_prod_write_addr_batch(struct xsk_queue *q, struct xdp_desc *descs,
u32 nb_entries)
{
Expand Down
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