net/core/xdp.c - linux/kernel/git/viro/vfs - Git at Google

 /* net/core/xdp.c
  *
  * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
  * Released under terms in GPL version 2.  See COPYING.
  */
 #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 <net/page_pool.h>

 #include <net/xdp.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;

 struct xdp_mem_allocator {
 	struct xdp_mem_info mem;
 	union {
 		void *allocator;
 		struct page_pool *page_pool;
 		struct zero_copy_allocator *zc_alloc;
 	};
 	struct rhash_head node;
 	struct rcu_head rcu;
 };

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

 	BUILD_BUG_ON(FIELD_SIZEOF(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 = FIELD_SIZEOF(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);

 	/* Notice, driver is expected to free the *allocator,
 	 * e.g. page_pool, and MUST also use RCU free.
 	 */

 	/* Poison memory */
 	xa->mem.id = 0xFFFF;
 	xa->mem.type = 0xF0F0;
 	xa->allocator = (void *)0xDEAD9001;

 	kfree(xa);
 }

 static 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 (id == 0)
 		return;

 	mutex_lock(&mem_id_lock);

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

 	mutex_unlock(&mem_id_lock);
 }

 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)
 {
 	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->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 || type == MEM_TYPE_ZERO_COPY)
 			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)) {
 		errno = PTR_ERR(ptr);
 		goto err;
 	}

 	mutex_unlock(&mem_id_lock);

 	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 boolian
  * 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,
 			 unsigned long handle)
 {
 	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 (xa) {
 			napi_direct &= !xdp_return_frame_no_direct();
 			page_pool_put_page(xa->page_pool, page, napi_direct);
 		} else {
 			put_page(page);
 		}
 		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_ZERO_COPY:
 		/* NB! Only valid from an xdp_buff! */
 		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);
 		xa->zc_alloc->free(xa->zc_alloc, handle);
 		rcu_read_unlock();
 	default:
 		/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
 		break;
 	}
 }

 void xdp_return_frame(struct xdp_frame *xdpf)
 {
 	__xdp_return(xdpf->data, &xdpf->mem, false, 0);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame);

 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 {
 	__xdp_return(xdpf->data, &xdpf->mem, true, 0);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);

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

 int xdp_attachment_query(struct xdp_attachment_info *info,
 			 struct netdev_bpf *bpf)
 {
 	bpf->prog_id = info->prog ? info->prog->aux->id : 0;
 	bpf->prog_flags = info->prog ? info->flags : 0;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xdp_attachment_query);

 bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
 			     struct netdev_bpf *bpf)
 {
 	if (info->prog && (bpf->flags ^ info->flags) & XDP_FLAGS_MODES) {
 		NL_SET_ERR_MSG(bpf->extack,
 			       "program loaded with different flags");
 		return false;
 	}
 	return true;
 }
 EXPORT_SYMBOL_GPL(xdp_attachment_flags_ok);

 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);
	/* net/core/xdp.c
	*
	* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
	* Released under terms in GPL version 2. See COPYING.
	*/
	#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 <net/page_pool.h>

	#include <net/xdp.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;

	struct xdp_mem_allocator {
	struct xdp_mem_info mem;
	union {
	void *allocator;
	struct page_pool *page_pool;
	struct zero_copy_allocator *zc_alloc;
	};
	struct rhash_head node;
	struct rcu_head rcu;
	};

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

	BUILD_BUG_ON(FIELD_SIZEOF(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 = FIELD_SIZEOF(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);

	/* Notice, driver is expected to free the *allocator,
	* e.g. page_pool, and MUST also use RCU free.
	*/

	/* Poison memory */
	xa->mem.id = 0xFFFF;
	xa->mem.type = 0xF0F0;
	xa->allocator = (void *)0xDEAD9001;

	kfree(xa);
	}

	static 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 (id == 0)
	return;

	mutex_lock(&mem_id_lock);

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

	mutex_unlock(&mem_id_lock);
	}

	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)
	{
	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->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 \|\| type == MEM_TYPE_ZERO_COPY)
	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)) {
	errno = PTR_ERR(ptr);
	goto err;
	}

	mutex_unlock(&mem_id_lock);

	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 boolian
	* 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,
	unsigned long handle)
	{
	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 (xa) {
	napi_direct &= !xdp_return_frame_no_direct();
	page_pool_put_page(xa->page_pool, page, napi_direct);
	} else {
	put_page(page);
	}
	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_ZERO_COPY:
	/* NB! Only valid from an xdp_buff! */
	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);
	xa->zc_alloc->free(xa->zc_alloc, handle);
	rcu_read_unlock();
	default:
	/* Not possible, checked in xdp_rxq_info_reg_mem_model() */
	break;
	}
	}

	void xdp_return_frame(struct xdp_frame *xdpf)
	{
	__xdp_return(xdpf->data, &xdpf->mem, false, 0);
	}
	EXPORT_SYMBOL_GPL(xdp_return_frame);

	void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
	{
	__xdp_return(xdpf->data, &xdpf->mem, true, 0);
	}
	EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);

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

	int xdp_attachment_query(struct xdp_attachment_info *info,
	struct netdev_bpf *bpf)
	{
	bpf->prog_id = info->prog ? info->prog->aux->id : 0;
	bpf->prog_flags = info->prog ? info->flags : 0;
	return 0;
	}
	EXPORT_SYMBOL_GPL(xdp_attachment_query);

	bool xdp_attachment_flags_ok(struct xdp_attachment_info *info,
	struct netdev_bpf *bpf)
	{
	if (info->prog && (bpf->flags ^ info->flags) & XDP_FLAGS_MODES) {
	NL_SET_ERR_MSG(bpf->extack,
	"program loaded with different flags");
	return false;
	}
	return true;
	}
	EXPORT_SYMBOL_GPL(xdp_attachment_flags_ok);

	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);