net/core/xdp.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /* net/core/xdp.c
  *
  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
  */
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/types.h>
 #include <linux/mm.h>
 #include <linux/netdevice.h>
 #include <linux/slab.h>
 #include <linux/idr.h>
 #include <linux/rhashtable.h>
 #include <linux/bug.h>
 #include <net/page_pool.h>

 #include <net/xdp.h>
 #include <net/xdp_priv.h> /* struct xdp_mem_allocator */
 #include <trace/events/xdp.h>
 #include <net/xdp_sock_drv.h>

 #define REG_STATE_NEW		0x0
 #define REG_STATE_REGISTERED	0x1
 #define REG_STATE_UNREGISTERED	0x2
 #define REG_STATE_UNUSED	0x3

 static DEFINE_IDA(mem_id_pool);
 static DEFINE_MUTEX(mem_id_lock);
 #define MEM_ID_MAX 0xFFFE
 #define MEM_ID_MIN 1
 static int mem_id_next = MEM_ID_MIN;

 static bool mem_id_init; /* false */
 static struct rhashtable *mem_id_ht;

 static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
 {
 	const u32 *k = data;
 	const u32 key = *k;

 	BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
 		     != sizeof(u32));

 	/* Use cyclic increasing ID as direct hash key */
 	return key;
 }

 static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
 			  const void *ptr)
 {
 	const struct xdp_mem_allocator *xa = ptr;
 	u32 mem_id = *(u32 *)arg->key;

 	return xa->mem.id != mem_id;
 }

 static const struct rhashtable_params mem_id_rht_params = {
 	.nelem_hint = 64,
 	.head_offset = offsetof(struct xdp_mem_allocator, node),
 	.key_offset  = offsetof(struct xdp_mem_allocator, mem.id),
 	.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
 	.max_size = MEM_ID_MAX,
 	.min_size = 8,
 	.automatic_shrinking = true,
 	.hashfn    = xdp_mem_id_hashfn,
 	.obj_cmpfn = xdp_mem_id_cmp,
 };

 static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
 {
 	struct xdp_mem_allocator *xa;

 	xa = container_of(rcu, struct xdp_mem_allocator, rcu);

 	/* Allow this ID to be reused */
 	ida_simple_remove(&mem_id_pool, xa->mem.id);

 	kfree(xa);
 }

 static void mem_xa_remove(struct xdp_mem_allocator *xa)
 {
 	trace_mem_disconnect(xa);

 	if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
 		call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
 }

 static void mem_allocator_disconnect(void *allocator)
 {
 	struct xdp_mem_allocator *xa;
 	struct rhashtable_iter iter;

 	mutex_lock(&mem_id_lock);

 	rhashtable_walk_enter(mem_id_ht, &iter);
 	do {
 		rhashtable_walk_start(&iter);

 		while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
 			if (xa->allocator == allocator)
 				mem_xa_remove(xa);
 		}

 		rhashtable_walk_stop(&iter);

 	} while (xa == ERR_PTR(-EAGAIN));
 	rhashtable_walk_exit(&iter);

 	mutex_unlock(&mem_id_lock);
 }

 void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
 {
 	struct xdp_mem_allocator *xa;
 	int id = xdp_rxq->mem.id;

 	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 		WARN(1, "Missing register, driver bug");
 		return;
 	}

 	if (id == 0)
 		return;

 	if (xdp_rxq->mem.type == MEM_TYPE_PAGE_POOL) {
 		rcu_read_lock();
 		xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
 		page_pool_destroy(xa->page_pool);
 		rcu_read_unlock();
 	}
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);

 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
 {
 	/* Simplify driver cleanup code paths, allow unreg "unused" */
 	if (xdp_rxq->reg_state == REG_STATE_UNUSED)
 		return;

 	WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");

 	xdp_rxq_info_unreg_mem_model(xdp_rxq);

 	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
 	xdp_rxq->dev = NULL;

 	/* Reset mem info to defaults */
 	xdp_rxq->mem.id = 0;
 	xdp_rxq->mem.type = 0;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);

 static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
 {
 	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
 }

 /* Returns 0 on success, negative on failure */
 int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
 		     struct net_device *dev, u32 queue_index, unsigned int napi_id)
 {
 	if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
 		WARN(1, "Driver promised not to register this");
 		return -EINVAL;
 	}

 	if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
 		WARN(1, "Missing unregister, handled but fix driver");
 		xdp_rxq_info_unreg(xdp_rxq);
 	}

 	if (!dev) {
 		WARN(1, "Missing net_device from driver");
 		return -ENODEV;
 	}

 	/* State either UNREGISTERED or NEW */
 	xdp_rxq_info_init(xdp_rxq);
 	xdp_rxq->dev = dev;
 	xdp_rxq->queue_index = queue_index;
 	xdp_rxq->napi_id = napi_id;

 	xdp_rxq->reg_state = REG_STATE_REGISTERED;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);

 void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
 {
 	xdp_rxq->reg_state = REG_STATE_UNUSED;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);

 bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
 {
 	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);

 static int __mem_id_init_hash_table(void)
 {
 	struct rhashtable *rht;
 	int ret;

 	if (unlikely(mem_id_init))
 		return 0;

 	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
 	if (!rht)
 		return -ENOMEM;

 	ret = rhashtable_init(rht, &mem_id_rht_params);
 	if (ret < 0) {
 		kfree(rht);
 		return ret;
 	}
 	mem_id_ht = rht;
 	smp_mb(); /* mutex lock should provide enough pairing */
 	mem_id_init = true;

 	return 0;
 }

 /* Allocate a cyclic ID that maps to allocator pointer.
  * See: https://www.kernel.org/doc/html/latest/core-api/idr.html
  *
  * Caller must lock mem_id_lock.
  */
 static int __mem_id_cyclic_get(gfp_t gfp)
 {
 	int retries = 1;
 	int id;

 again:
 	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
 	if (id < 0) {
 		if (id == -ENOSPC) {
 			/* Cyclic allocator, reset next id */
 			if (retries--) {
 				mem_id_next = MEM_ID_MIN;
 				goto again;
 			}
 		}
 		return id; /* errno */
 	}
 	mem_id_next = id + 1;

 	return id;
 }

 static bool __is_supported_mem_type(enum xdp_mem_type type)
 {
 	if (type == MEM_TYPE_PAGE_POOL)
 		return is_page_pool_compiled_in();

 	if (type >= MEM_TYPE_MAX)
 		return false;

 	return true;
 }

 int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
 			       enum xdp_mem_type type, void *allocator)
 {
 	struct xdp_mem_allocator *xdp_alloc;
 	gfp_t gfp = GFP_KERNEL;
 	int id, errno, ret;
 	void *ptr;

 	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
 		WARN(1, "Missing register, driver bug");
 		return -EFAULT;
 	}

 	if (!__is_supported_mem_type(type))
 		return -EOPNOTSUPP;

 	xdp_rxq->mem.type = type;

 	if (!allocator) {
 		if (type == MEM_TYPE_PAGE_POOL)
 			return -EINVAL; /* Setup time check page_pool req */
 		return 0;
 	}

 	/* Delay init of rhashtable to save memory if feature isn't used */
 	if (!mem_id_init) {
 		mutex_lock(&mem_id_lock);
 		ret = __mem_id_init_hash_table();
 		mutex_unlock(&mem_id_lock);
 		if (ret < 0) {
 			WARN_ON(1);
 			return ret;
 		}
 	}

 	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
 	if (!xdp_alloc)
 		return -ENOMEM;

 	mutex_lock(&mem_id_lock);
 	id = __mem_id_cyclic_get(gfp);
 	if (id < 0) {
 		errno = id;
 		goto err;
 	}
 	xdp_rxq->mem.id = id;
 	xdp_alloc->mem  = xdp_rxq->mem;
 	xdp_alloc->allocator = allocator;

 	/* Insert allocator into ID lookup table */
 	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
 	if (IS_ERR(ptr)) {
 		ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
 		xdp_rxq->mem.id = 0;
 		errno = PTR_ERR(ptr);
 		goto err;
 	}

 	if (type == MEM_TYPE_PAGE_POOL)
 		page_pool_use_xdp_mem(allocator, mem_allocator_disconnect);

 	mutex_unlock(&mem_id_lock);

 	trace_mem_connect(xdp_alloc, xdp_rxq);
 	return 0;
 err:
 	mutex_unlock(&mem_id_lock);
 	kfree(xdp_alloc);
 	return errno;
 }
 EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);

 /* XDP RX runs under NAPI protection, and in different delivery error
  * scenarios (e.g. queue full), it is possible to return the xdp_frame
  * while still leveraging this protection.  The @napi_direct boolean
  * is used for those calls sites.  Thus, allowing for faster recycling
  * of xdp_frames/pages in those cases.
  */
 static void __xdp_return(void *data, struct xdp_mem_info *mem, bool napi_direct,
 			 struct xdp_buff *xdp)
 {
 	struct xdp_mem_allocator *xa;
 	struct page *page;

 	switch (mem->type) {
 	case MEM_TYPE_PAGE_POOL:
 		rcu_read_lock();
 		/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
 		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 		page = virt_to_head_page(data);
 		if (napi_direct && xdp_return_frame_no_direct())
 			napi_direct = false;
 		page_pool_put_full_page(xa->page_pool, page, napi_direct);
 		rcu_read_unlock();
 		break;
 	case MEM_TYPE_PAGE_SHARED:
 		page_frag_free(data);
 		break;
 	case MEM_TYPE_PAGE_ORDER0:
 		page = virt_to_page(data); /* Assumes order0 page*/
 		put_page(page);
 		break;
 	case MEM_TYPE_XSK_BUFF_POOL:
 		/* NB! Only valid from an xdp_buff! */
 		xsk_buff_free(xdp);
 		break;
 	default:
 		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
 		WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
 		break;
 	}
 }

 void xdp_return_frame(struct xdp_frame *xdpf)
 {
 	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame);

 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 {
 	__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);

 /* XDP bulk APIs introduce a defer/flush mechanism to return
  * pages belonging to the same xdp_mem_allocator object
  * (identified via the mem.id field) in bulk to optimize
  * I-cache and D-cache.
  * The bulk queue size is set to 16 to be aligned to how
  * XDP_REDIRECT bulking works. The bulk is flushed when
  * it is full or when mem.id changes.
  * xdp_frame_bulk is usually stored/allocated on the function
  * call-stack to avoid locking penalties.
  */
 void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
 {
 	struct xdp_mem_allocator *xa = bq->xa;

 	if (unlikely(!xa || !bq->count))
 		return;

 	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
 	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
 	bq->count = 0;
 }
 EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);

 /* Must be called with rcu_read_lock held */
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq)
 {
 	struct xdp_mem_info *mem = &xdpf->mem;
 	struct xdp_mem_allocator *xa;

 	if (mem->type != MEM_TYPE_PAGE_POOL) {
 		__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
 		return;
 	}

 	xa = bq->xa;
 	if (unlikely(!xa)) {
 		xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 		bq->count = 0;
 		bq->xa = xa;
 	}

 	if (bq->count == XDP_BULK_QUEUE_SIZE)
 		xdp_flush_frame_bulk(bq);

 	if (unlikely(mem->id != xa->mem.id)) {
 		xdp_flush_frame_bulk(bq);
 		bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 	}

 	bq->q[bq->count++] = xdpf->data;
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);

 void xdp_return_buff(struct xdp_buff *xdp)
 {
 	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
 }

 /* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
 void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
 {
 	struct xdp_mem_allocator *xa;
 	struct page *page;

 	rcu_read_lock();
 	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
 	page = virt_to_head_page(data);
 	if (xa)
 		page_pool_release_page(xa->page_pool, page);
 	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(__xdp_release_frame);

 void xdp_attachment_setup(struct xdp_attachment_info *info,
 			  struct netdev_bpf *bpf)
 {
 	if (info->prog)
 		bpf_prog_put(info->prog);
 	info->prog = bpf->prog;
 	info->flags = bpf->flags;
 }
 EXPORT_SYMBOL_GPL(xdp_attachment_setup);

 struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp)
 {
 	unsigned int metasize, totsize;
 	void *addr, *data_to_copy;
 	struct xdp_frame *xdpf;
 	struct page *page;

 	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
 	metasize = xdp_data_meta_unsupported(xdp) ? 0 :
 		   xdp->data - xdp->data_meta;
 	totsize = xdp->data_end - xdp->data + metasize;

 	if (sizeof(*xdpf) + totsize > PAGE_SIZE)
 		return NULL;

 	page = dev_alloc_page();
 	if (!page)
 		return NULL;

 	addr = page_to_virt(page);
 	xdpf = addr;
 	memset(xdpf, 0, sizeof(*xdpf));

 	addr += sizeof(*xdpf);
 	data_to_copy = metasize ? xdp->data_meta : xdp->data;
 	memcpy(addr, data_to_copy, totsize);

 	xdpf->data = addr + metasize;
 	xdpf->len = totsize - metasize;
 	xdpf->headroom = 0;
 	xdpf->metasize = metasize;
 	xdpf->frame_sz = PAGE_SIZE;
 	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;

 	xsk_buff_free(xdp);
 	return xdpf;
 }
 EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);

 /* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
 void xdp_warn(const char *msg, const char *func, const int line)
 {
 	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
 };
 EXPORT_SYMBOL_GPL(xdp_warn);

 int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
 {
 	n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
 				      n_skb, skbs);
 	if (unlikely(!n_skb))
 		return -ENOMEM;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);

 struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 					   struct sk_buff *skb,
 					   struct net_device *dev)
 {
 	unsigned int headroom, frame_size;
 	void *hard_start;

 	/* Part of headroom was reserved to xdpf */
 	headroom = sizeof(*xdpf) + xdpf->headroom;

 	/* Memory size backing xdp_frame data already have reserved
 	 * room for build_skb to place skb_shared_info in tailroom.
 	 */
 	frame_size = xdpf->frame_sz;

 	hard_start = xdpf->data - headroom;
 	skb = build_skb_around(skb, hard_start, frame_size);
 	if (unlikely(!skb))
 		return NULL;

 	skb_reserve(skb, headroom);
 	__skb_put(skb, xdpf->len);
 	if (xdpf->metasize)
 		skb_metadata_set(skb, xdpf->metasize);

 	/* Essential SKB info: protocol and skb->dev */
 	skb->protocol = eth_type_trans(skb, dev);

 	/* Optional SKB info, currently missing:
 	 * - HW checksum info		(skb->ip_summed)
 	 * - HW RX hash			(skb_set_hash)
 	 * - RX ring dev queue index	(skb_record_rx_queue)
 	 */

 	/* Until page_pool get SKB return path, release DMA here */
 	xdp_release_frame(xdpf);

 	/* Allow SKB to reuse area used by xdp_frame */
 	xdp_scrub_frame(xdpf);

 	return skb;
 }
 EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);

 struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
 					 struct net_device *dev)
 {
 	struct sk_buff *skb;

 	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
 	if (unlikely(!skb))
 		return NULL;

 	memset(skb, 0, offsetof(struct sk_buff, tail));

 	return __xdp_build_skb_from_frame(xdpf, skb, dev);
 }
 EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);
	// SPDX-License-Identifier: GPL-2.0-only
	/* net/core/xdp.c
	*
	* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
	*/
	#include <linux/bpf.h>
	#include <linux/filter.h>
	#include <linux/types.h>
	#include <linux/mm.h>
	#include <linux/netdevice.h>
	#include <linux/slab.h>
	#include <linux/idr.h>
	#include <linux/rhashtable.h>
	#include <linux/bug.h>
	#include <net/page_pool.h>

	#include <net/xdp.h>
	#include <net/xdp_priv.h> /* struct xdp_mem_allocator */
	#include <trace/events/xdp.h>
	#include <net/xdp_sock_drv.h>

	#define REG_STATE_NEW 0x0
	#define REG_STATE_REGISTERED 0x1
	#define REG_STATE_UNREGISTERED 0x2
	#define REG_STATE_UNUSED 0x3

	static DEFINE_IDA(mem_id_pool);
	static DEFINE_MUTEX(mem_id_lock);
	#define MEM_ID_MAX 0xFFFE
	#define MEM_ID_MIN 1
	static int mem_id_next = MEM_ID_MIN;

	static bool mem_id_init; /* false */
	static struct rhashtable *mem_id_ht;

	static u32 xdp_mem_id_hashfn(const void *data, u32 len, u32 seed)
	{
	const u32 *k = data;
	const u32 key = *k;

	BUILD_BUG_ON(sizeof_field(struct xdp_mem_allocator, mem.id)
	!= sizeof(u32));

	/* Use cyclic increasing ID as direct hash key */
	return key;
	}

	static int xdp_mem_id_cmp(struct rhashtable_compare_arg *arg,
	const void *ptr)
	{
	const struct xdp_mem_allocator *xa = ptr;
	u32 mem_id = (u32 )arg->key;

	return xa->mem.id != mem_id;
	}

	static const struct rhashtable_params mem_id_rht_params = {
	.nelem_hint = 64,
	.head_offset = offsetof(struct xdp_mem_allocator, node),
	.key_offset = offsetof(struct xdp_mem_allocator, mem.id),
	.key_len = sizeof_field(struct xdp_mem_allocator, mem.id),
	.max_size = MEM_ID_MAX,
	.min_size = 8,
	.automatic_shrinking = true,
	.hashfn = xdp_mem_id_hashfn,
	.obj_cmpfn = xdp_mem_id_cmp,
	};

	static void __xdp_mem_allocator_rcu_free(struct rcu_head *rcu)
	{
	struct xdp_mem_allocator *xa;

	xa = container_of(rcu, struct xdp_mem_allocator, rcu);

	/* Allow this ID to be reused */
	ida_simple_remove(&mem_id_pool, xa->mem.id);

	kfree(xa);
	}

	static void mem_xa_remove(struct xdp_mem_allocator *xa)
	{
	trace_mem_disconnect(xa);

	if (!rhashtable_remove_fast(mem_id_ht, &xa->node, mem_id_rht_params))
	call_rcu(&xa->rcu, __xdp_mem_allocator_rcu_free);
	}

	static void mem_allocator_disconnect(void *allocator)
	{
	struct xdp_mem_allocator *xa;
	struct rhashtable_iter iter;

	mutex_lock(&mem_id_lock);

	rhashtable_walk_enter(mem_id_ht, &iter);
	do {
	rhashtable_walk_start(&iter);

	while ((xa = rhashtable_walk_next(&iter)) && !IS_ERR(xa)) {
	if (xa->allocator == allocator)
	mem_xa_remove(xa);
	}

	rhashtable_walk_stop(&iter);

	} while (xa == ERR_PTR(-EAGAIN));
	rhashtable_walk_exit(&iter);

	mutex_unlock(&mem_id_lock);
	}

	void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq)
	{
	struct xdp_mem_allocator *xa;
	int id = xdp_rxq->mem.id;

	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
	WARN(1, "Missing register, driver bug");
	return;
	}

	if (id == 0)
	return;

	if (xdp_rxq->mem.type == MEM_TYPE_PAGE_POOL) {
	rcu_read_lock();
	xa = rhashtable_lookup(mem_id_ht, &id, mem_id_rht_params);
	page_pool_destroy(xa->page_pool);
	rcu_read_unlock();
	}
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg_mem_model);

	void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
	{
	/* Simplify driver cleanup code paths, allow unreg "unused" */
	if (xdp_rxq->reg_state == REG_STATE_UNUSED)
	return;

	WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");

	xdp_rxq_info_unreg_mem_model(xdp_rxq);

	xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
	xdp_rxq->dev = NULL;

	/* Reset mem info to defaults */
	xdp_rxq->mem.id = 0;
	xdp_rxq->mem.type = 0;
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);

	static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
	{
	memset(xdp_rxq, 0, sizeof(*xdp_rxq));
	}

	/* Returns 0 on success, negative on failure */
	int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
	struct net_device *dev, u32 queue_index, unsigned int napi_id)
	{
	if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
	WARN(1, "Driver promised not to register this");
	return -EINVAL;
	}

	if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
	WARN(1, "Missing unregister, handled but fix driver");
	xdp_rxq_info_unreg(xdp_rxq);
	}

	if (!dev) {
	WARN(1, "Missing net_device from driver");
	return -ENODEV;
	}

	/* State either UNREGISTERED or NEW */
	xdp_rxq_info_init(xdp_rxq);
	xdp_rxq->dev = dev;
	xdp_rxq->queue_index = queue_index;
	xdp_rxq->napi_id = napi_id;

	xdp_rxq->reg_state = REG_STATE_REGISTERED;
	return 0;
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);

	void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
	{
	xdp_rxq->reg_state = REG_STATE_UNUSED;
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);

	bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq)
	{
	return (xdp_rxq->reg_state == REG_STATE_REGISTERED);
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_is_reg);

	static int __mem_id_init_hash_table(void)
	{
	struct rhashtable *rht;
	int ret;

	if (unlikely(mem_id_init))
	return 0;

	rht = kzalloc(sizeof(*rht), GFP_KERNEL);
	if (!rht)
	return -ENOMEM;

	ret = rhashtable_init(rht, &mem_id_rht_params);
	if (ret < 0) {
	kfree(rht);
	return ret;
	}
	mem_id_ht = rht;
	smp_mb(); /* mutex lock should provide enough pairing */
	mem_id_init = true;

	return 0;
	}

	/* Allocate a cyclic ID that maps to allocator pointer.
	* See: https://www.kernel.org/doc/html/latest/core-api/idr.html
	*
	* Caller must lock mem_id_lock.
	*/
	static int __mem_id_cyclic_get(gfp_t gfp)
	{
	int retries = 1;
	int id;

	again:
	id = ida_simple_get(&mem_id_pool, mem_id_next, MEM_ID_MAX, gfp);
	if (id < 0) {
	if (id == -ENOSPC) {
	/* Cyclic allocator, reset next id */
	if (retries--) {
	mem_id_next = MEM_ID_MIN;
	goto again;
	}
	}
	return id; /* errno */
	}
	mem_id_next = id + 1;

	return id;
	}

	static bool __is_supported_mem_type(enum xdp_mem_type type)
	{
	if (type == MEM_TYPE_PAGE_POOL)
	return is_page_pool_compiled_in();

	if (type >= MEM_TYPE_MAX)
	return false;

	return true;
	}

	int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
	enum xdp_mem_type type, void *allocator)
	{
	struct xdp_mem_allocator *xdp_alloc;
	gfp_t gfp = GFP_KERNEL;
	int id, errno, ret;
	void *ptr;

	if (xdp_rxq->reg_state != REG_STATE_REGISTERED) {
	WARN(1, "Missing register, driver bug");
	return -EFAULT;
	}

	if (!__is_supported_mem_type(type))
	return -EOPNOTSUPP;

	xdp_rxq->mem.type = type;

	if (!allocator) {
	if (type == MEM_TYPE_PAGE_POOL)
	return -EINVAL; /* Setup time check page_pool req */
	return 0;
	}

	/* Delay init of rhashtable to save memory if feature isn't used */
	if (!mem_id_init) {
	mutex_lock(&mem_id_lock);
	ret = __mem_id_init_hash_table();
	mutex_unlock(&mem_id_lock);
	if (ret < 0) {
	WARN_ON(1);
	return ret;
	}
	}

	xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);
	if (!xdp_alloc)
	return -ENOMEM;

	mutex_lock(&mem_id_lock);
	id = __mem_id_cyclic_get(gfp);
	if (id < 0) {
	errno = id;
	goto err;
	}
	xdp_rxq->mem.id = id;
	xdp_alloc->mem = xdp_rxq->mem;
	xdp_alloc->allocator = allocator;

	/* Insert allocator into ID lookup table */
	ptr = rhashtable_insert_slow(mem_id_ht, &id, &xdp_alloc->node);
	if (IS_ERR(ptr)) {
	ida_simple_remove(&mem_id_pool, xdp_rxq->mem.id);
	xdp_rxq->mem.id = 0;
	errno = PTR_ERR(ptr);
	goto err;
	}

	if (type == MEM_TYPE_PAGE_POOL)
	page_pool_use_xdp_mem(allocator, mem_allocator_disconnect);

	mutex_unlock(&mem_id_lock);

	trace_mem_connect(xdp_alloc, xdp_rxq);
	return 0;
	err:
	mutex_unlock(&mem_id_lock);
	kfree(xdp_alloc);
	return errno;
	}
	EXPORT_SYMBOL_GPL(xdp_rxq_info_reg_mem_model);

	/* XDP RX runs under NAPI protection, and in different delivery error
	* scenarios (e.g. queue full), it is possible to return the xdp_frame
	* while still leveraging this protection. The @napi_direct boolean
	* is used for those calls sites. Thus, allowing for faster recycling
	* of xdp_frames/pages in those cases.
	*/
	static void __xdp_return(void data, struct xdp_mem_info mem, bool napi_direct,
	struct xdp_buff *xdp)
	{
	struct xdp_mem_allocator *xa;
	struct page *page;

	switch (mem->type) {
	case MEM_TYPE_PAGE_POOL:
	rcu_read_lock();
	/* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	page = virt_to_head_page(data);
	if (napi_direct && xdp_return_frame_no_direct())
	napi_direct = false;
	page_pool_put_full_page(xa->page_pool, page, napi_direct);
	rcu_read_unlock();
	break;
	case MEM_TYPE_PAGE_SHARED:
	page_frag_free(data);
	break;
	case MEM_TYPE_PAGE_ORDER0:
	page = virt_to_page(data); /* Assumes order0 page*/
	put_page(page);
	break;
	case MEM_TYPE_XSK_BUFF_POOL:
	/* NB! Only valid from an xdp_buff! */
	xsk_buff_free(xdp);
	break;
	default:
	/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
	WARN(1, "Incorrect XDP memory type (%d) usage", mem->type);
	break;
	}
	}

	void xdp_return_frame(struct xdp_frame *xdpf)
	{
	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
	}
	EXPORT_SYMBOL_GPL(xdp_return_frame);

	void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
	{
	__xdp_return(xdpf->data, &xdpf->mem, true, NULL);
	}
	EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);

	/* XDP bulk APIs introduce a defer/flush mechanism to return
	* pages belonging to the same xdp_mem_allocator object
	* (identified via the mem.id field) in bulk to optimize
	* I-cache and D-cache.
	* The bulk queue size is set to 16 to be aligned to how
	* XDP_REDIRECT bulking works. The bulk is flushed when
	* it is full or when mem.id changes.
	* xdp_frame_bulk is usually stored/allocated on the function
	* call-stack to avoid locking penalties.
	*/
	void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
	{
	struct xdp_mem_allocator *xa = bq->xa;

	if (unlikely(!xa \|\| !bq->count))
	return;

	page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
	/* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
	bq->count = 0;
	}
	EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);

	/* Must be called with rcu_read_lock held */
	void xdp_return_frame_bulk(struct xdp_frame *xdpf,
	struct xdp_frame_bulk *bq)
	{
	struct xdp_mem_info *mem = &xdpf->mem;
	struct xdp_mem_allocator *xa;

	if (mem->type != MEM_TYPE_PAGE_POOL) {
	__xdp_return(xdpf->data, &xdpf->mem, false, NULL);
	return;
	}

	xa = bq->xa;
	if (unlikely(!xa)) {
	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	bq->count = 0;
	bq->xa = xa;
	}

	if (bq->count == XDP_BULK_QUEUE_SIZE)
	xdp_flush_frame_bulk(bq);

	if (unlikely(mem->id != xa->mem.id)) {
	xdp_flush_frame_bulk(bq);
	bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	}

	bq->q[bq->count++] = xdpf->data;
	}
	EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);

	void xdp_return_buff(struct xdp_buff *xdp)
	{
	__xdp_return(xdp->data, &xdp->rxq->mem, true, xdp);
	}

	/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
	void __xdp_release_frame(void data, struct xdp_mem_info mem)
	{
	struct xdp_mem_allocator *xa;
	struct page *page;

	rcu_read_lock();
	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
	page = virt_to_head_page(data);
	if (xa)
	page_pool_release_page(xa->page_pool, page);
	rcu_read_unlock();
	}
	EXPORT_SYMBOL_GPL(__xdp_release_frame);

	void xdp_attachment_setup(struct xdp_attachment_info *info,
	struct netdev_bpf *bpf)
	{
	if (info->prog)
	bpf_prog_put(info->prog);
	info->prog = bpf->prog;
	info->flags = bpf->flags;
	}
	EXPORT_SYMBOL_GPL(xdp_attachment_setup);

	struct xdp_frame xdp_convert_zc_to_xdp_frame(struct xdp_buff xdp)
	{
	unsigned int metasize, totsize;
	void addr, data_to_copy;
	struct xdp_frame *xdpf;
	struct page *page;

	/* Clone into a MEM_TYPE_PAGE_ORDER0 xdp_frame. */
	metasize = xdp_data_meta_unsupported(xdp) ? 0 :
	xdp->data - xdp->data_meta;
	totsize = xdp->data_end - xdp->data + metasize;

	if (sizeof(*xdpf) + totsize > PAGE_SIZE)
	return NULL;

	page = dev_alloc_page();
	if (!page)
	return NULL;

	addr = page_to_virt(page);
	xdpf = addr;
	memset(xdpf, 0, sizeof(*xdpf));

	addr += sizeof(*xdpf);
	data_to_copy = metasize ? xdp->data_meta : xdp->data;
	memcpy(addr, data_to_copy, totsize);

	xdpf->data = addr + metasize;
	xdpf->len = totsize - metasize;
	xdpf->headroom = 0;
	xdpf->metasize = metasize;
	xdpf->frame_sz = PAGE_SIZE;
	xdpf->mem.type = MEM_TYPE_PAGE_ORDER0;

	xsk_buff_free(xdp);
	return xdpf;
	}
	EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame);

	/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */
	void xdp_warn(const char msg, const char func, const int line)
	{
	WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg);
	};
	EXPORT_SYMBOL_GPL(xdp_warn);

	int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
	{
	n_skb = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
	n_skb, skbs);
	if (unlikely(!n_skb))
	return -ENOMEM;

	return 0;
	}
	EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);

	struct sk_buff __xdp_build_skb_from_frame(struct xdp_frame xdpf,
	struct sk_buff *skb,
	struct net_device *dev)
	{
	unsigned int headroom, frame_size;
	void *hard_start;

	/* Part of headroom was reserved to xdpf */
	headroom = sizeof(*xdpf) + xdpf->headroom;

	/* Memory size backing xdp_frame data already have reserved
	* room for build_skb to place skb_shared_info in tailroom.
	*/
	frame_size = xdpf->frame_sz;

	hard_start = xdpf->data - headroom;
	skb = build_skb_around(skb, hard_start, frame_size);
	if (unlikely(!skb))
	return NULL;

	skb_reserve(skb, headroom);
	__skb_put(skb, xdpf->len);
	if (xdpf->metasize)
	skb_metadata_set(skb, xdpf->metasize);

	/* Essential SKB info: protocol and skb->dev */
	skb->protocol = eth_type_trans(skb, dev);

	/* Optional SKB info, currently missing:
	* - HW checksum info (skb->ip_summed)
	* - HW RX hash (skb_set_hash)
	* - RX ring dev queue index (skb_record_rx_queue)
	*/

	/* Until page_pool get SKB return path, release DMA here */
	xdp_release_frame(xdpf);

	/* Allow SKB to reuse area used by xdp_frame */
	xdp_scrub_frame(xdpf);

	return skb;
	}
	EXPORT_SYMBOL_GPL(__xdp_build_skb_from_frame);

	struct sk_buff xdp_build_skb_from_frame(struct xdp_frame xdpf,
	struct net_device *dev)
	{
	struct sk_buff *skb;

	skb = kmem_cache_alloc(skbuff_head_cache, GFP_ATOMIC);
	if (unlikely(!skb))
	return NULL;

	memset(skb, 0, offsetof(struct sk_buff, tail));

	return __xdp_build_skb_from_frame(xdpf, skb, dev);
	}
	EXPORT_SYMBOL_GPL(xdp_build_skb_from_frame);