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Commit 98158f5a authored by David S. Miller's avatar David S. Miller
Browse files

inetpeer: Abstract out the tree root accesses. 



Instead of directly accessing "peer", change to code to
operate using a "struct inet_peer_base *" pointer.

This will facilitate the addition of a seperate tree for
ipv6 peer entries.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c20ec761

net/ipv4/inetpeer.c

+69 −50
Original line number Diff line number Diff line
@@ -79,13 +79,13 @@ static const struct inet_peer peer_fake_node = { 
	.avl_height	= 0

};



static struct {

static struct inet_peer_base {

	struct inet_peer __rcu *root;

	spinlock_t	lock;

	int		total;

} peers = {

} v4_peers = {

	.root		= peer_avl_empty_rcu,

	.lock		= __SPIN_LOCK_UNLOCKED(peers.lock),

	.lock		= __SPIN_LOCK_UNLOCKED(v4_peers.lock),

	.total		= 0,

};

#define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */
@@ -155,15 +155,15 @@ static void unlink_from_unused(struct inet_peer *p) 
/*

 * Called with local BH disabled and the pool lock held.

 */

#define lookup(_daddr, _stack) 					\

#define lookup(_daddr, _stack, _base)				\

({								\

	struct inet_peer *u;					\

	struct inet_peer __rcu **v;				\

								\

	stackptr = _stack;					\

	*stackptr++ = &peers.root;				\

	for (u = rcu_dereference_protected(peers.root,		\

			lockdep_is_held(&peers.lock));		\

	*stackptr++ = &_base->root;				\

	for (u = rcu_dereference_protected(_base->root,		\

			lockdep_is_held(&_base->lock));		\

	     u != peer_avl_empty; ) {				\

		if (_daddr == u->v4daddr)			\

			break;					\
@@ -173,7 +173,7 @@ static void unlink_from_unused(struct inet_peer *p) 
			v = &u->avl_right;			\

		*stackptr++ = v;				\

		u = rcu_dereference_protected(*v,		\

			lockdep_is_held(&peers.lock));		\

			lockdep_is_held(&_base->lock));		\

	}							\

	u;							\

})
@@ -185,9 +185,9 @@ static void unlink_from_unused(struct inet_peer *p) 
 * But every pointer we follow is guaranteed to be valid thanks to RCU.

 * We exit from this function if number of links exceeds PEER_MAXDEPTH

 */

static struct inet_peer *lookup_rcu_bh(__be32 daddr)

static struct inet_peer *lookup_rcu_bh(__be32 daddr, struct inet_peer_base *base)

{

	struct inet_peer *u = rcu_dereference_bh(peers.root);

	struct inet_peer *u = rcu_dereference_bh(base->root);

	int count = 0;



	while (u != peer_avl_empty) {
@@ -212,19 +212,19 @@ static struct inet_peer *lookup_rcu_bh(__be32 daddr) 
}



/* Called with local BH disabled and the pool lock held. */

#define lookup_rightempty(start)				\

#define lookup_rightempty(start, base)				\

({								\

	struct inet_peer *u;					\

	struct inet_peer __rcu **v;				\

	*stackptr++ = &start->avl_left;				\

	v = &start->avl_left;					\

	for (u = rcu_dereference_protected(*v,			\

			lockdep_is_held(&peers.lock));		\

			lockdep_is_held(&base->lock));		\

	     u->avl_right != peer_avl_empty_rcu; ) {		\

		v = &u->avl_right;				\

		*stackptr++ = v;				\

		u = rcu_dereference_protected(*v,		\

			lockdep_is_held(&peers.lock));		\

			lockdep_is_held(&base->lock));		\

	}							\

	u;							\

})
@@ -234,7 +234,8 @@ static struct inet_peer *lookup_rcu_bh(__be32 daddr) 
 * Look into mm/map_avl.c for more detail description of the ideas.

 */

static void peer_avl_rebalance(struct inet_peer __rcu **stack[],

		struct inet_peer __rcu ***stackend)

			       struct inet_peer __rcu ***stackend,

			       struct inet_peer_base *base)

{

	struct inet_peer __rcu **nodep;

	struct inet_peer *node, *l, *r;
@@ -243,20 +244,20 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 
	while (stackend > stack) {

		nodep = *--stackend;

		node = rcu_dereference_protected(*nodep,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

		l = rcu_dereference_protected(node->avl_left,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

		r = rcu_dereference_protected(node->avl_right,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

		lh = node_height(l);

		rh = node_height(r);

		if (lh > rh + 1) { /* l: RH+2 */

			struct inet_peer *ll, *lr, *lrl, *lrr;

			int lrh;

			ll = rcu_dereference_protected(l->avl_left,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

			lr = rcu_dereference_protected(l->avl_right,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

			lrh = node_height(lr);

			if (lrh <= node_height(ll)) {	/* ll: RH+1 */

				RCU_INIT_POINTER(node->avl_left, lr);	/* lr: RH or RH+1 */
@@ -268,9 +269,9 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 
				RCU_INIT_POINTER(*nodep, l);

			} else { /* ll: RH, lr: RH+1 */

				lrl = rcu_dereference_protected(lr->avl_left,

					lockdep_is_held(&peers.lock));	/* lrl: RH or RH-1 */

					lockdep_is_held(&base->lock));	/* lrl: RH or RH-1 */

				lrr = rcu_dereference_protected(lr->avl_right,

					lockdep_is_held(&peers.lock));	/* lrr: RH or RH-1 */

					lockdep_is_held(&base->lock));	/* lrr: RH or RH-1 */

				RCU_INIT_POINTER(node->avl_left, lrr);	/* lrr: RH or RH-1 */

				RCU_INIT_POINTER(node->avl_right, r);	/* r: RH */

				node->avl_height = rh + 1; /* node: RH+1 */
@@ -286,9 +287,9 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 
			struct inet_peer *rr, *rl, *rlr, *rll;

			int rlh;

			rr = rcu_dereference_protected(r->avl_right,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

			rl = rcu_dereference_protected(r->avl_left,

				lockdep_is_held(&peers.lock));

				lockdep_is_held(&base->lock));

			rlh = node_height(rl);

			if (rlh <= node_height(rr)) {	/* rr: LH+1 */

				RCU_INIT_POINTER(node->avl_right, rl);	/* rl: LH or LH+1 */
@@ -300,9 +301,9 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 
				RCU_INIT_POINTER(*nodep, r);

			} else { /* rr: RH, rl: RH+1 */

				rlr = rcu_dereference_protected(rl->avl_right,

					lockdep_is_held(&peers.lock));	/* rlr: LH or LH-1 */

					lockdep_is_held(&base->lock));	/* rlr: LH or LH-1 */

				rll = rcu_dereference_protected(rl->avl_left,

					lockdep_is_held(&peers.lock));	/* rll: LH or LH-1 */

					lockdep_is_held(&base->lock));	/* rll: LH or LH-1 */

				RCU_INIT_POINTER(node->avl_right, rll);	/* rll: LH or LH-1 */

				RCU_INIT_POINTER(node->avl_left, l);	/* l: LH */

				node->avl_height = lh + 1; /* node: LH+1 */
@@ -321,14 +322,14 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 
}



/* Called with local BH disabled and the pool lock held. */

#define link_to_pool(n)						\

#define link_to_pool(n, base)					\

do {								\

	n->avl_height = 1;					\

	n->avl_left = peer_avl_empty_rcu;			\

	n->avl_right = peer_avl_empty_rcu;			\

	/* lockless readers can catch us now */			\

	rcu_assign_pointer(**--stackptr, n);			\

	peer_avl_rebalance(stack, stackptr);			\

	peer_avl_rebalance(stack, stackptr, base);		\

} while (0)



static void inetpeer_free_rcu(struct rcu_head *head)
@@ -337,13 +338,13 @@ static void inetpeer_free_rcu(struct rcu_head *head) 
}



/* May be called with local BH enabled. */

static void unlink_from_pool(struct inet_peer *p)

static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base)

{

	int do_free;



	do_free = 0;



	spin_lock_bh(&peers.lock);

	spin_lock_bh(&base->lock);

	/* Check the reference counter.  It was artificially incremented by 1

	 * in cleanup() function to prevent sudden disappearing.  If we can

	 * atomically (because of lockless readers) take this last reference,
@@ -353,7 +354,7 @@ static void unlink_from_pool(struct inet_peer *p) 
	if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) {

		struct inet_peer __rcu **stack[PEER_MAXDEPTH];

		struct inet_peer __rcu ***stackptr, ***delp;

		if (lookup(p->v4daddr, stack) != p)

		if (lookup(p->v4daddr, stack, base) != p)

			BUG();

		delp = stackptr - 1; /* *delp[0] == p */

		if (p->avl_left == peer_avl_empty_rcu) {
@@ -362,9 +363,9 @@ static void unlink_from_pool(struct inet_peer *p) 
		} else {

			/* look for a node to insert instead of p */

			struct inet_peer *t;

			t = lookup_rightempty(p);

			t = lookup_rightempty(p, base);

			BUG_ON(rcu_dereference_protected(*stackptr[-1],

					lockdep_is_held(&peers.lock)) != t);

					lockdep_is_held(&base->lock)) != t);

			**--stackptr = t->avl_left;

			/* t is removed, t->v4daddr > x->v4daddr for any

			 * x in p->avl_left subtree.
@@ -376,11 +377,11 @@ static void unlink_from_pool(struct inet_peer *p) 
			BUG_ON(delp[1] != &p->avl_left);

			delp[1] = &t->avl_left; /* was &p->avl_left */

		}

		peer_avl_rebalance(stack, stackptr);

		peers.total--;

		peer_avl_rebalance(stack, stackptr, base);

		base->total--;

		do_free = 1;

	}

	spin_unlock_bh(&peers.lock);

	spin_unlock_bh(&base->lock);



	if (do_free)

		call_rcu_bh(&p->rcu, inetpeer_free_rcu);
@@ -395,6 +396,11 @@ static void unlink_from_pool(struct inet_peer *p) 
		inet_putpeer(p);

}



static struct inet_peer_base *peer_to_base(struct inet_peer *p)

{

	return &v4_peers;

}



/* May be called with local BH enabled. */

static int cleanup_once(unsigned long ttl)

{
@@ -428,21 +434,27 @@ static int cleanup_once(unsigned long ttl) 
		 * happen because of entry limits in route cache. */

		return -1;



	unlink_from_pool(p);

	unlink_from_pool(p, peer_to_base(p));

	return 0;

}



static struct inet_peer_base *family_to_base(int family)

{

	return &v4_peers;

}



/* Called with or without local BH being disabled. */

struct inet_peer *inet_getpeer(__be32 daddr, int create)

{

	struct inet_peer *p;

	struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr;

	struct inet_peer_base *base = family_to_base(AF_INET);

	struct inet_peer *p;



	/* Look up for the address quickly, lockless.

	 * Because of a concurrent writer, we might not find an existing entry.

	 */

	rcu_read_lock_bh();

	p = lookup_rcu_bh(daddr);

	p = lookup_rcu_bh(daddr, base);

	rcu_read_unlock_bh();



	if (p) {
@@ -456,11 +468,11 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create) 
	/* retry an exact lookup, taking the lock before.

	 * At least, nodes should be hot in our cache.

	 */

	spin_lock_bh(&peers.lock);

	p = lookup(daddr, stack);

	spin_lock_bh(&base->lock);

	p = lookup(daddr, stack, base);

	if (p != peer_avl_empty) {

		atomic_inc(&p->refcnt);

		spin_unlock_bh(&peers.lock);

		spin_unlock_bh(&base->lock);

		/* Remove the entry from unused list if it was there. */

		unlink_from_unused(p);

		return p;
@@ -476,30 +488,36 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create) 




		/* Link the node. */

		link_to_pool(p);

		peers.total++;

		link_to_pool(p, base);

		base->total++;

	}

	spin_unlock_bh(&peers.lock);

	spin_unlock_bh(&base->lock);



	if (peers.total >= inet_peer_threshold)

	if (base->total >= inet_peer_threshold)

		/* Remove one less-recently-used entry. */

		cleanup_once(0);



	return p;

}



static int compute_total(void)

{

	return v4_peers.total;

}



/* Called with local BH disabled. */

static void peer_check_expire(unsigned long dummy)

{

	unsigned long now = jiffies;

	int ttl;

	int ttl, total;



	if (peers.total >= inet_peer_threshold)

	total = compute_total();

	if (total >= inet_peer_threshold)

		ttl = inet_peer_minttl;

	else

		ttl = inet_peer_maxttl

				- (inet_peer_maxttl - inet_peer_minttl) / HZ *

					peers.total / inet_peer_threshold * HZ;

					total / inet_peer_threshold * HZ;

	while (!cleanup_once(ttl)) {

		if (jiffies != now)

			break;
@@ -508,13 +526,14 @@ static void peer_check_expire(unsigned long dummy) 
	/* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime

	 * interval depending on the total number of entries (more entries,

	 * less interval). */

	if (peers.total >= inet_peer_threshold)

	total = compute_total();

	if (total >= inet_peer_threshold)

		peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime;

	else

		peer_periodic_timer.expires = jiffies

			+ inet_peer_gc_maxtime

			- (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ *

				peers.total / inet_peer_threshold * HZ;

				total / inet_peer_threshold * HZ;

	add_timer(&peer_periodic_timer);

}