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     庵ﾉノ李ﾀｿﾆ 	    /* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_FRAG_H__
#define __NET_FRAG_H__

#include <linux/rhashtable-types.h>
#include <linux/completion.h>
#include <linux/in6.h>
#include <linux/rbtree_types.h>
#include <linux/refcount.h>
#include <net/dropreason-core.h>

/* Per netns frag queues directory */
struct fqdir {
	/* sysctls */
	long			high_thresh;
	long			low_thresh;
	int			timeout;
	int			max_dist;
	struct inet_frags	*f;
	struct net		*net;
	bool			dead;

	struct rhashtable       rhashtable ____cacheline_aligned_in_smp;

	/* Keep atomic mem on separate cachelines in structs that include it */
	atomic_long_t		mem ____cacheline_aligned_in_smp;
	struct work_struct	destroy_work;
	struct llist_node	free_list;
};

/**
 * fragment queue flags
 *
 * @INET_FRAG_FIRST_IN: first fragment has arrived
 * @INET_FRAG_LAST_IN: final fragment has arrived
 * @INET_FRAG_COMPLETE: frag queue has been processed and is due for destruction
 * @INET_FRAG_HASH_DEAD: inet_frag_kill() has not removed fq from rhashtable
 * @INET_FRAG_DROP: if skbs must be dropped (instead of being consumed)
 */
enum {
	INET_FRAG_FIRST_IN	= BIT(0),
	INET_FRAG_LAST_IN	= BIT(1),
	INET_FRAG_COMPLETE	= BIT(2),
	INET_FRAG_HASH_DEAD	= BIT(3),
	INET_FRAG_DROP		= BIT(4),
};

struct frag_v4_compare_key {
	__be32		saddr;
	__be32		daddr;
	u32		user;
	u32		vif;
	__be16		id;
	u16		protocol;
};

struct frag_v6_compare_key {
	struct in6_addr	saddr;
	struct in6_addr	daddr;
	u32		user;
	__be32		id;
	u32		iif;
};

/**
 * struct inet_frag_queue - fragment queue
 *
 * @node: rhash node
 * @key: keys identifying this frag.
 * @timer: queue expiration timer
 * @lock: spinlock protecting this frag
 * @refcnt: reference count of the queue
 * @rb_fragments: received fragments rb-tree root
 * @fragments_tail: received fragments tail
 * @last_run_head: the head of the last "run". see ip_fragment.c
 * @stamp: timestamp of the last received fragment
 * @len: total length of the original datagram
 * @meat: length of received fragments so far
 * @mono_delivery_time: stamp has a mono delivery time (EDT)
 * @flags: fragment queue flags
 * @max_size: maximum received fragment size
 * @fqdir: pointer to struct fqdir
 * @rcu: rcu head for freeing deferall
 */
struct inet_frag_queue {
	struct rhash_head	node;
	union {
		struct frag_v4_compare_key v4;
		struct frag_v6_compare_key v6;
	} key;
	struct timer_list	timer;
	spinlock_t		lock;
	refcount_t		refcnt;
	struct rb_root		rb_fragments;
	struct sk_buff		*fragments_tail;
	struct sk_buff		*last_run_head;
	ktime_t			stamp;
	int			len;
	int			meat;
	u8			mono_delivery_time;
	__u8			flags;
	u16			max_size;
	struct fqdir		*fqdir;
	struct rcu_head		rcu;
};

struct inet_frags {
	unsigned int		qsize;

	void			(*constructor)(struct inet_frag_queue *q,
					       const void *arg);
	void			(*destructor)(struct inet_frag_queue *);
	void			(*frag_expire)(struct timer_list *t);
	struct kmem_cache	*frags_cachep;
	const char		*frags_cache_name;
	struct rhashtable_params rhash_params;
	refcount_t		refcnt;
	struct completion	completion;
};

int inet_frags_init(struct inet_frags *);
void inet_frags_fini(struct inet_frags *);

int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net);

static inline void fqdir_pre_exit(struct fqdir *fqdir)
{
	/* Prevent creation of new frags.
	 * Pairs with READ_ONCE() in inet_frag_find().
	 */
	WRITE_ONCE(fqdir->high_thresh, 0);

	/* Pairs with READ_ONCE() in inet_frag_kill(), ip_expire()
	 * and ip6frag_expire_frag_queue().
	 */
	WRITE_ONCE(fqdir->dead, true);
}
void fqdir_exit(struct fqdir *fqdir);

void inet_frag_kill(struct inet_frag_queue *q);
void inet_frag_destroy(struct inet_frag_queue *q);
struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key);

/* Free all skbs in the queue; return the sum of their truesizes. */
unsigned int inet_frag_rbtree_purge(struct rb_root *root,
				    enum skb_drop_reason reason);

static inline void inet_frag_put(struct inet_frag_queue *q)
{
	if (refcount_dec_and_test(&q->refcnt))
		inet_frag_destroy(q);
}

/* Memory Tracking Fu