inet_frag.h
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#ifndef __NET_FRAG_H__
#define __NET_FRAG_H__
#include <linux/percpu_counter.h>
struct netns_frags {
/* The percpu_counter "mem" need to be cacheline aligned.
* mem.count must not share cacheline with other writers
*/
struct percpu_counter mem ____cacheline_aligned_in_smp;
/* sysctls */
int timeout;
int high_thresh;
int low_thresh;
};
/**
* 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
*/
enum {
INET_FRAG_FIRST_IN = BIT(0),
INET_FRAG_LAST_IN = BIT(1),
INET_FRAG_COMPLETE = BIT(2),
};
/**
* struct inet_frag_queue - fragment queue
*
* @lock: spinlock protecting the queue
* @timer: queue expiration timer
* @list: hash bucket list
* @refcnt: reference count of the queue
* @fragments: received fragments head
* @fragments_tail: received fragments tail
* @stamp: timestamp of the last received fragment
* @len: total length of the original datagram
* @meat: length of received fragments so far
* @flags: fragment queue flags
* @max_size: maximum received fragment size
* @net: namespace that this frag belongs to
* @list_evictor: list of queues to forcefully evict (e.g. due to low memory)
*/
struct inet_frag_queue {
spinlock_t lock;
struct timer_list timer;
struct hlist_node list;
atomic_t refcnt;
struct sk_buff *fragments;
struct sk_buff *fragments_tail;
ktime_t stamp;
int len;
int meat;
__u8 flags;
u16 max_size;
struct netns_frags *net;
struct hlist_node list_evictor;
};
#define INETFRAGS_HASHSZ 1024
/* averaged:
* max_depth = default ipfrag_high_thresh / INETFRAGS_HASHSZ /
* rounded up (SKB_TRUELEN(0) + sizeof(struct ipq or
* struct frag_queue))
*/
#define INETFRAGS_MAXDEPTH 128
struct inet_frag_bucket {
struct hlist_head chain;
spinlock_t chain_lock;
};
struct inet_frags {
struct inet_frag_bucket hash[INETFRAGS_HASHSZ];
struct work_struct frags_work;
unsigned int next_bucket;
unsigned long last_rebuild_jiffies;
bool rebuild;
/* The first call to hashfn is responsible to initialize
* rnd. This is best done with net_get_random_once.
*
* rnd_seqlock is used to let hash insertion detect
* when it needs to re-lookup the hash chain to use.
*/
u32 rnd;
seqlock_t rnd_seqlock;
int qsize;
unsigned int (*hashfn)(const struct inet_frag_queue *);
bool (*match)(const struct inet_frag_queue *q,
const void *arg);
void (*constructor)(struct inet_frag_queue *q,
const void *arg);
void (*destructor)(struct inet_frag_queue *);
void (*skb_free)(struct sk_buff *);
void (*frag_expire)(unsigned long data);
struct kmem_cache *frags_cachep;
const char *frags_cache_name;
};
int inet_frags_init(struct inet_frags *);
void inet_frags_fini(struct inet_frags *);
static inline int inet_frags_init_net(struct netns_frags *nf)
{
return percpu_counter_init(&nf->mem, 0, GFP_KERNEL);
}
static inline void inet_frags_uninit_net(struct netns_frags *nf)
{
percpu_counter_destroy(&nf->mem);
}
void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f);
void inet_frag_kill(struct inet_frag_queue *q, struct inet_frags *f);
void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f);
struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
struct inet_frags *f, void *key, unsigned int hash);
void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
const char *prefix);
static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
{
if (atomic_dec_and_test(&q->refcnt))
inet_frag_destroy(q, f);
}
static inline bool inet_frag_evicting(struct inet_frag_queue *q)
{
return !hlist_unhashed(&q->list_evictor);
}
/* Memory Tracking Functions. */
/* The default percpu_counter batch size is not big enough to scale to
* fragmentation mem acct sizes.
* The mem size of a 64K fragment is approx:
* (44 fragments * 2944 truesize) + frag_queue struct(200) = 129736 bytes
*/
static unsigned int frag_percpu_counter_batch = 130000;
static inline int frag_mem_limit(struct netns_frags *nf)
{
return percpu_counter_read(&nf->mem);
}
static inline void sub_frag_mem_limit(struct netns_frags *nf, int i)
{
__percpu_counter_add(&nf->mem, -i, frag_percpu_counter_batch);
}
static inline void add_frag_mem_limit(struct netns_frags *nf, int i)
{
__percpu_counter_add(&nf->mem, i, frag_percpu_counter_batch);
}
static inline unsigned int sum_frag_mem_limit(struct netns_frags *nf)
{
unsigned int res;
local_bh_disable();
res = percpu_counter_sum_positive(&nf->mem);
local_bh_enable();
return res;
}
/* RFC 3168 support :
* We want to check ECN values of all fragments, do detect invalid combinations.
* In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value.
*/
#define IPFRAG_ECN_NOT_ECT 0x01 /* one frag had ECN_NOT_ECT */
#define IPFRAG_ECN_ECT_1 0x02 /* one frag had ECN_ECT_1 */
#define IPFRAG_ECN_ECT_0 0x04 /* one frag had ECN_ECT_0 */
#define IPFRAG_ECN_CE 0x08 /* one frag had ECN_CE */
extern const u8 ip_frag_ecn_table[16];
#endif