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inetpeer: Abstract out the tree root accesses.
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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: David S. Miller <davem@davemloft.net>
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David S. Miller committed Nov 30, 2010
1 parent c20ec76 commit 98158f5
Showing 1 changed file with 69 additions and 50 deletions.
119 changes: 69 additions & 50 deletions net/ipv4/inetpeer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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; \
Expand All @@ -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; \
})
Expand All @@ -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) {
Expand All @@ -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; \
})
Expand All @@ -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;
Expand All @@ -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 */
Expand All @@ -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 */
Expand All @@ -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 */
Expand All @@ -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 */
Expand All @@ -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)
Expand All @@ -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,
Expand All @@ -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) {
Expand All @@ -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.
Expand All @@ -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);
Expand All @@ -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)
{
Expand Down Expand Up @@ -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) {
Expand All @@ -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;
Expand All @@ -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;
Expand All @@ -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);
}

Expand Down

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