diff options
| -rw-r--r-- | net/ipv4/inetpeer.c | 75 |
1 files changed, 35 insertions, 40 deletions
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c index 48f8d4592cc..f604ffdbea2 100644 --- a/net/ipv4/inetpeer.c +++ b/net/ipv4/inetpeer.c @@ -81,19 +81,19 @@ static const struct inet_peer peer_fake_node = { struct inet_peer_base { struct inet_peer __rcu *root; - spinlock_t lock; + seqlock_t lock; int total; }; static struct inet_peer_base v4_peers = { .root = peer_avl_empty_rcu, - .lock = __SPIN_LOCK_UNLOCKED(v4_peers.lock), + .lock = __SEQLOCK_UNLOCKED(v4_peers.lock), .total = 0, }; static struct inet_peer_base v6_peers = { .root = peer_avl_empty_rcu, - .lock = __SPIN_LOCK_UNLOCKED(v6_peers.lock), + .lock = __SEQLOCK_UNLOCKED(v6_peers.lock), .total = 0, }; @@ -177,6 +177,9 @@ static int addr_compare(const struct inetpeer_addr *a, return 0; } +#define rcu_deref_locked(X, BASE) \ + rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock)) + /* * Called with local BH disabled and the pool lock held. */ @@ -187,8 +190,7 @@ static int addr_compare(const struct inetpeer_addr *a, \ stackptr = _stack; \ *stackptr++ = &_base->root; \ - for (u = rcu_dereference_protected(_base->root, \ - lockdep_is_held(&_base->lock)); \ + for (u = rcu_deref_locked(_base->root, _base); \ u != peer_avl_empty; ) { \ int cmp = addr_compare(_daddr, &u->daddr); \ if (cmp == 0) \ @@ -198,8 +200,7 @@ static int addr_compare(const struct inetpeer_addr *a, else \ v = &u->avl_right; \ *stackptr++ = v; \ - u = rcu_dereference_protected(*v, \ - lockdep_is_held(&_base->lock)); \ + u = rcu_deref_locked(*v, _base); \ } \ u; \ }) @@ -246,13 +247,11 @@ static struct inet_peer *lookup_rcu_bh(const struct inetpeer_addr *daddr, struct inet_peer __rcu **v; \ *stackptr++ = &start->avl_left; \ v = &start->avl_left; \ - for (u = rcu_dereference_protected(*v, \ - lockdep_is_held(&base->lock)); \ + for (u = rcu_deref_locked(*v, base); \ u->avl_right != peer_avl_empty_rcu; ) { \ v = &u->avl_right; \ *stackptr++ = v; \ - u = rcu_dereference_protected(*v, \ - lockdep_is_held(&base->lock)); \ + u = rcu_deref_locked(*v, base); \ } \ u; \ }) @@ -271,21 +270,16 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], while (stackend > stack) { nodep = *--stackend; - node = rcu_dereference_protected(*nodep, - lockdep_is_held(&base->lock)); - l = rcu_dereference_protected(node->avl_left, - lockdep_is_held(&base->lock)); - r = rcu_dereference_protected(node->avl_right, - lockdep_is_held(&base->lock)); + node = rcu_deref_locked(*nodep, base); + l = rcu_deref_locked(node->avl_left, base); + r = rcu_deref_locked(node->avl_right, base); 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(&base->lock)); - lr = rcu_dereference_protected(l->avl_right, - lockdep_is_held(&base->lock)); + ll = rcu_deref_locked(l->avl_left, base); + lr = rcu_deref_locked(l->avl_right, base); lrh = node_height(lr); if (lrh <= node_height(ll)) { /* ll: RH+1 */ RCU_INIT_POINTER(node->avl_left, lr); /* lr: RH or RH+1 */ @@ -296,10 +290,8 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], l->avl_height = node->avl_height + 1; RCU_INIT_POINTER(*nodep, l); } else { /* ll: RH, lr: RH+1 */ - lrl = rcu_dereference_protected(lr->avl_left, - lockdep_is_held(&base->lock)); /* lrl: RH or RH-1 */ - lrr = rcu_dereference_protected(lr->avl_right, - lockdep_is_held(&base->lock)); /* lrr: RH or RH-1 */ + lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */ + lrr = rcu_deref_locked(lr->avl_right, base);/* 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 */ @@ -314,10 +306,8 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], } else if (rh > lh + 1) { /* r: LH+2 */ struct inet_peer *rr, *rl, *rlr, *rll; int rlh; - rr = rcu_dereference_protected(r->avl_right, - lockdep_is_held(&base->lock)); - rl = rcu_dereference_protected(r->avl_left, - lockdep_is_held(&base->lock)); + rr = rcu_deref_locked(r->avl_right, base); + rl = rcu_deref_locked(r->avl_left, base); rlh = node_height(rl); if (rlh <= node_height(rr)) { /* rr: LH+1 */ RCU_INIT_POINTER(node->avl_right, rl); /* rl: LH or LH+1 */ @@ -328,10 +318,8 @@ static void peer_avl_rebalance(struct inet_peer __rcu **stack[], r->avl_height = node->avl_height + 1; RCU_INIT_POINTER(*nodep, r); } else { /* rr: RH, rl: RH+1 */ - rlr = rcu_dereference_protected(rl->avl_right, - lockdep_is_held(&base->lock)); /* rlr: LH or LH-1 */ - rll = rcu_dereference_protected(rl->avl_left, - lockdep_is_held(&base->lock)); /* rll: LH or LH-1 */ + rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */ + rll = rcu_deref_locked(rl->avl_left, base);/* 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 */ @@ -372,7 +360,7 @@ static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base) do_free = 0; - spin_lock_bh(&base->lock); + write_seqlock_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, @@ -392,8 +380,7 @@ static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base) /* look for a node to insert instead of p */ struct inet_peer *t; t = lookup_rightempty(p, base); - BUG_ON(rcu_dereference_protected(*stackptr[-1], - lockdep_is_held(&base->lock)) != t); + BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t); **--stackptr = t->avl_left; /* t is removed, t->daddr > x->daddr for any * x in p->avl_left subtree. @@ -409,7 +396,7 @@ static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base) base->total--; do_free = 1; } - spin_unlock_bh(&base->lock); + write_sequnlock_bh(&base->lock); if (do_free) call_rcu_bh(&p->rcu, inetpeer_free_rcu); @@ -477,12 +464,16 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr; struct inet_peer_base *base = family_to_base(daddr->family); struct inet_peer *p; + unsigned int sequence; + int invalidated; /* Look up for the address quickly, lockless. * Because of a concurrent writer, we might not find an existing entry. */ rcu_read_lock_bh(); + sequence = read_seqbegin(&base->lock); p = lookup_rcu_bh(daddr, base); + invalidated = read_seqretry(&base->lock, sequence); rcu_read_unlock_bh(); if (p) { @@ -493,14 +484,18 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) return p; } + /* If no writer did a change during our lookup, we can return early. */ + if (!create && !invalidated) + return NULL; + /* retry an exact lookup, taking the lock before. * At least, nodes should be hot in our cache. */ - spin_lock_bh(&base->lock); + write_seqlock_bh(&base->lock); p = lookup(daddr, stack, base); if (p != peer_avl_empty) { atomic_inc(&p->refcnt); - spin_unlock_bh(&base->lock); + write_sequnlock_bh(&base->lock); /* Remove the entry from unused list if it was there. */ unlink_from_unused(p); return p; @@ -524,7 +519,7 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) link_to_pool(p, base); base->total++; } - spin_unlock_bh(&base->lock); + write_sequnlock_bh(&base->lock); if (base->total >= inet_peer_threshold) /* Remove one less-recently-used entry. */ |