diff options
| -rw-r--r-- | include/net/inet_frag.h | 8 | ||||
| -rw-r--r-- | net/ipv4/inet_fragment.c | 57 |
2 files changed, 51 insertions, 14 deletions
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index 7cac9c5..6f41b45 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -50,10 +50,16 @@ struct inet_frag_queue { */ #define INETFRAGS_MAXDEPTH 128 +struct inet_frag_bucket { + struct hlist_head chain; + spinlock_t chain_lock; +}; + struct inet_frags { - struct hlist_head hash[INETFRAGS_HASHSZ]; + struct inet_frag_bucket hash[INETFRAGS_HASHSZ]; /* This rwlock is a global lock (seperate per IPv4, IPv6 and * netfilter). Important to keep this on a seperate cacheline. + * Its primarily a rebuild protection rwlock. */ rwlock_t lock ____cacheline_aligned_in_smp; int secret_interval; diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 1206ca6..e97d66a 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -52,20 +52,27 @@ static void inet_frag_secret_rebuild(unsigned long dummy) unsigned long now = jiffies; int i; + /* Per bucket lock NOT needed here, due to write lock protection */ write_lock(&f->lock); + get_random_bytes(&f->rnd, sizeof(u32)); for (i = 0; i < INETFRAGS_HASHSZ; i++) { + struct inet_frag_bucket *hb; struct inet_frag_queue *q; struct hlist_node *n; - hlist_for_each_entry_safe(q, n, &f->hash[i], list) { + hb = &f->hash[i]; + hlist_for_each_entry_safe(q, n, &hb->chain, list) { unsigned int hval = f->hashfn(q); if (hval != i) { + struct inet_frag_bucket *hb_dest; + hlist_del(&q->list); /* Relink to new hash chain. */ - hlist_add_head(&q->list, &f->hash[hval]); + hb_dest = &f->hash[hval]; + hlist_add_head(&q->list, &hb_dest->chain); } } } @@ -78,9 +85,12 @@ void inet_frags_init(struct inet_frags *f) { int i; - for (i = 0; i < INETFRAGS_HASHSZ; i++) - INIT_HLIST_HEAD(&f->hash[i]); + for (i = 0; i < INETFRAGS_HASHSZ; i++) { + struct inet_frag_bucket *hb = &f->hash[i]; + spin_lock_init(&hb->chain_lock); + INIT_HLIST_HEAD(&hb->chain); + } rwlock_init(&f->lock); f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ @@ -122,9 +132,18 @@ EXPORT_SYMBOL(inet_frags_exit_net); static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) { - write_lock(&f->lock); + struct inet_frag_bucket *hb; + unsigned int hash; + + read_lock(&f->lock); + hash = f->hashfn(fq); + hb = &f->hash[hash]; + + spin_lock(&hb->chain_lock); hlist_del(&fq->list); - write_unlock(&f->lock); + spin_unlock(&hb->chain_lock); + + read_unlock(&f->lock); inet_frag_lru_del(fq); } @@ -226,27 +245,32 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf, struct inet_frag_queue *qp_in, struct inet_frags *f, void *arg) { + struct inet_frag_bucket *hb; struct inet_frag_queue *qp; #ifdef CONFIG_SMP #endif unsigned int hash; - write_lock(&f->lock); + read_lock(&f->lock); /* Protects against hash rebuild */ /* * While we stayed w/o the lock other CPU could update * the rnd seed, so we need to re-calculate the hash * chain. Fortunatelly the qp_in can be used to get one. */ hash = f->hashfn(qp_in); + hb = &f->hash[hash]; + spin_lock(&hb->chain_lock); + #ifdef CONFIG_SMP /* With SMP race we have to recheck hash table, because * such entry could be created on other cpu, while we - * promoted read lock to write lock. + * released the hash bucket lock. */ - hlist_for_each_entry(qp, &f->hash[hash], list) { + hlist_for_each_entry(qp, &hb->chain, list) { if (qp->net == nf && f->match(qp, arg)) { atomic_inc(&qp->refcnt); - write_unlock(&f->lock); + spin_unlock(&hb->chain_lock); + read_unlock(&f->lock); qp_in->last_in |= INET_FRAG_COMPLETE; inet_frag_put(qp_in, f); return qp; @@ -258,8 +282,9 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf, atomic_inc(&qp->refcnt); atomic_inc(&qp->refcnt); - hlist_add_head(&qp->list, &f->hash[hash]); - write_unlock(&f->lock); + hlist_add_head(&qp->list, &hb->chain); + spin_unlock(&hb->chain_lock); + read_unlock(&f->lock); inet_frag_lru_add(nf, qp); return qp; } @@ -300,17 +325,23 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, struct inet_frags *f, void *key, unsigned int hash) __releases(&f->lock) { + struct inet_frag_bucket *hb; struct inet_frag_queue *q; int depth = 0; - hlist_for_each_entry(q, &f->hash[hash], list) { + hb = &f->hash[hash]; + + spin_lock(&hb->chain_lock); + hlist_for_each_entry(q, &hb->chain, list) { if (q->net == nf && f->match(q, key)) { atomic_inc(&q->refcnt); + spin_unlock(&hb->chain_lock); read_unlock(&f->lock); return q; } depth++; } + spin_unlock(&hb->chain_lock); read_unlock(&f->lock); if (depth <= INETFRAGS_MAXDEPTH) |
