2 * net/core/dst.c Protocol independent destination cache.
4 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
8 #include <linux/bitops.h>
9 #include <linux/errno.h>
10 #include <linux/init.h>
11 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/netdevice.h>
15 #include <linux/sched.h>
16 #include <linux/skbuff.h>
17 #include <linux/string.h>
18 #include <linux/types.h>
23 * 1) Garbage collection state of dead destination cache
24 * entries is protected by dst_lock.
25 * 2) GC is run only from BH context, and is the only remover
27 * 3) Entries are added to the garbage list from both BH
28 * and non-BH context, so local BH disabling is needed.
29 * 4) All operations modify state, so a spinlock is used.
31 static struct dst_entry
*dst_garbage_list
;
32 #if RT_CACHE_DEBUG >= 2
33 static atomic_t dst_total
= ATOMIC_INIT(0);
35 static DEFINE_SPINLOCK(dst_lock
);
37 static unsigned long dst_gc_timer_expires
;
38 static unsigned long dst_gc_timer_inc
= DST_GC_MAX
;
39 static void dst_run_gc(unsigned long);
40 static void ___dst_free(struct dst_entry
* dst
);
42 static struct timer_list dst_gc_timer
=
43 TIMER_INITIALIZER(dst_run_gc
, DST_GC_MIN
, 0);
45 static void dst_run_gc(unsigned long dummy
)
49 struct dst_entry
* dst
, **dstp
;
51 if (!spin_trylock(&dst_lock
)) {
52 mod_timer(&dst_gc_timer
, jiffies
+ HZ
/10);
56 del_timer(&dst_gc_timer
);
57 dstp
= &dst_garbage_list
;
59 while ((dst
= *dstp
) != NULL
) {
60 if (atomic_read(&dst
->__refcnt
)) {
68 dst
= dst_destroy(dst
);
70 /* NOHASH and still referenced. Unless it is already
71 * on gc list, invalidate it and add to gc list.
73 * Note: this is temporary. Actually, NOHASH dst's
74 * must be obsoleted when parent is obsoleted.
75 * But we do not have state "obsoleted, but
76 * referenced by parent", so it is right.
78 if (dst
->obsolete
> 1)
87 if (!dst_garbage_list
) {
88 dst_gc_timer_inc
= DST_GC_MAX
;
91 if (!work_performed
) {
92 if ((dst_gc_timer_expires
+= dst_gc_timer_inc
) > DST_GC_MAX
)
93 dst_gc_timer_expires
= DST_GC_MAX
;
94 dst_gc_timer_inc
+= DST_GC_INC
;
96 dst_gc_timer_inc
= DST_GC_INC
;
97 dst_gc_timer_expires
= DST_GC_MIN
;
99 dst_gc_timer
.expires
= jiffies
+ dst_gc_timer_expires
;
100 #if RT_CACHE_DEBUG >= 2
101 printk("dst_total: %d/%d %ld\n",
102 atomic_read(&dst_total
), delayed
, dst_gc_timer_expires
);
104 add_timer(&dst_gc_timer
);
107 spin_unlock(&dst_lock
);
110 static int dst_discard_in(struct sk_buff
*skb
)
116 static int dst_discard_out(struct sk_buff
*skb
)
122 void * dst_alloc(struct dst_ops
* ops
)
124 struct dst_entry
* dst
;
126 if (ops
->gc
&& atomic_read(&ops
->entries
) > ops
->gc_thresh
) {
130 dst
= kmem_cache_alloc(ops
->kmem_cachep
, SLAB_ATOMIC
);
133 memset(dst
, 0, ops
->entry_size
);
134 atomic_set(&dst
->__refcnt
, 0);
136 dst
->lastuse
= jiffies
;
138 dst
->input
= dst_discard_in
;
139 dst
->output
= dst_discard_out
;
140 #if RT_CACHE_DEBUG >= 2
141 atomic_inc(&dst_total
);
143 atomic_inc(&ops
->entries
);
147 static void ___dst_free(struct dst_entry
* dst
)
149 /* The first case (dev==NULL) is required, when
150 protocol module is unloaded.
152 if (dst
->dev
== NULL
|| !(dst
->dev
->flags
&IFF_UP
)) {
153 dst
->input
= dst_discard_in
;
154 dst
->output
= dst_discard_out
;
159 void __dst_free(struct dst_entry
* dst
)
161 spin_lock_bh(&dst_lock
);
163 dst
->next
= dst_garbage_list
;
164 dst_garbage_list
= dst
;
165 if (dst_gc_timer_inc
> DST_GC_INC
) {
166 dst_gc_timer_inc
= DST_GC_INC
;
167 dst_gc_timer_expires
= DST_GC_MIN
;
168 mod_timer(&dst_gc_timer
, jiffies
+ dst_gc_timer_expires
);
170 spin_unlock_bh(&dst_lock
);
173 struct dst_entry
*dst_destroy(struct dst_entry
* dst
)
175 struct dst_entry
*child
;
176 struct neighbour
*neigh
;
182 neigh
= dst
->neighbour
;
187 if (hh
&& atomic_dec_and_test(&hh
->hh_refcnt
))
191 dst
->neighbour
= NULL
;
192 neigh_release(neigh
);
195 atomic_dec(&dst
->ops
->entries
);
197 if (dst
->ops
->destroy
)
198 dst
->ops
->destroy(dst
);
201 #if RT_CACHE_DEBUG >= 2
202 atomic_dec(&dst_total
);
204 kmem_cache_free(dst
->ops
->kmem_cachep
, dst
);
208 int nohash
= dst
->flags
& DST_NOHASH
;
210 if (atomic_dec_and_test(&dst
->__refcnt
)) {
211 /* We were real parent of this dst, so kill child. */
215 /* Child is still referenced, return it for freeing. */
218 /* Child is still in his hash table */
224 /* Dirty hack. We did it in 2.2 (in __dst_free),
225 * we have _very_ good reasons not to repeat
226 * this mistake in 2.3, but we have no choice
227 * now. _It_ _is_ _explicit_ _deliberate_
228 * _race_ _condition_.
230 * Commented and originally written by Alexey.
232 static inline void dst_ifdown(struct dst_entry
*dst
, struct net_device
*dev
,
235 if (dst
->ops
->ifdown
)
236 dst
->ops
->ifdown(dst
, dev
, unregister
);
242 dst
->input
= dst_discard_in
;
243 dst
->output
= dst_discard_out
;
245 dst
->dev
= &loopback_dev
;
246 dev_hold(&loopback_dev
);
248 if (dst
->neighbour
&& dst
->neighbour
->dev
== dev
) {
249 dst
->neighbour
->dev
= &loopback_dev
;
251 dev_hold(&loopback_dev
);
256 static int dst_dev_event(struct notifier_block
*this, unsigned long event
, void *ptr
)
258 struct net_device
*dev
= ptr
;
259 struct dst_entry
*dst
;
262 case NETDEV_UNREGISTER
:
264 spin_lock_bh(&dst_lock
);
265 for (dst
= dst_garbage_list
; dst
; dst
= dst
->next
) {
266 dst_ifdown(dst
, dev
, event
!= NETDEV_DOWN
);
268 spin_unlock_bh(&dst_lock
);
274 static struct notifier_block dst_dev_notifier
= {
275 .notifier_call
= dst_dev_event
,
278 void __init
dst_init(void)
280 register_netdevice_notifier(&dst_dev_notifier
);
283 EXPORT_SYMBOL(__dst_free
);
284 EXPORT_SYMBOL(dst_alloc
);
285 EXPORT_SYMBOL(dst_destroy
);