--- zzzz-none-000/linux-3.10.107/net/ipv4/inet_fragment.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/net/ipv4/inet_fragment.c	2021-02-04 17:41:59.000000000 +0000
@@ -25,6 +25,12 @@
 #include <net/inet_frag.h>
 #include <net/inet_ecn.h>
 
+#define INETFRAGS_EVICT_BUCKETS   128
+#define INETFRAGS_EVICT_MAX	  512
+
+/* don't rebuild inetfrag table with new secret more often than this */
+#define INETFRAGS_MIN_REBUILD_INTERVAL (5 * HZ)
+
 /* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
  * Value : 0xff if frame should be dropped.
  *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
@@ -46,24 +52,39 @@
 };
 EXPORT_SYMBOL(ip_frag_ecn_table);
 
-static void inet_frag_secret_rebuild(unsigned long dummy)
+static unsigned int
+inet_frag_hashfn(const struct inet_frags *f, const struct inet_frag_queue *q)
+{
+	return f->hashfn(q) & (INETFRAGS_HASHSZ - 1);
+}
+
+static bool inet_frag_may_rebuild(struct inet_frags *f)
+{
+	return time_after(jiffies,
+	       f->last_rebuild_jiffies + INETFRAGS_MIN_REBUILD_INTERVAL);
+}
+
+static void inet_frag_secret_rebuild(struct inet_frags *f)
 {
-	struct inet_frags *f = (struct inet_frags *)dummy;
-	unsigned long now = jiffies;
 	int i;
 
-	/* Per bucket lock NOT needed here, due to write lock protection */
-	write_lock(&f->lock);
+	write_seqlock_bh(&f->rnd_seqlock);
+
+	if (!inet_frag_may_rebuild(f))
+		goto out;
 
 	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;
 
 		hb = &f->hash[i];
+		spin_lock(&hb->chain_lock);
+
 		hlist_for_each_entry_safe(q, n, &hb->chain, list) {
-			unsigned int hval = f->hashfn(q);
+			unsigned int hval = inet_frag_hashfn(f, q);
 
 			if (hval != i) {
 				struct inet_frag_bucket *hb_dest;
@@ -72,79 +93,184 @@
 
 				/* Relink to new hash chain. */
 				hb_dest = &f->hash[hval];
+
+				/* This is the only place where we take
+				 * another chain_lock while already holding
+				 * one.  As this will not run concurrently,
+				 * we cannot deadlock on hb_dest lock below, if its
+				 * already locked it will be released soon since
+				 * other caller cannot be waiting for hb lock
+				 * that we've taken above.
+				 */
+				spin_lock_nested(&hb_dest->chain_lock,
+						 SINGLE_DEPTH_NESTING);
 				hlist_add_head(&q->list, &hb_dest->chain);
+				spin_unlock(&hb_dest->chain_lock);
 			}
 		}
+		spin_unlock(&hb->chain_lock);
+	}
+
+	f->rebuild = false;
+	f->last_rebuild_jiffies = jiffies;
+out:
+	write_sequnlock_bh(&f->rnd_seqlock);
+}
+
+static bool inet_fragq_should_evict(const struct inet_frag_queue *q)
+{
+	return q->net->low_thresh == 0 ||
+	       frag_mem_limit(q->net) >= q->net->low_thresh;
+}
+
+static unsigned int
+inet_evict_bucket(struct inet_frags *f, struct inet_frag_bucket *hb)
+{
+	struct inet_frag_queue *fq;
+	struct hlist_node *n;
+	unsigned int evicted = 0;
+	HLIST_HEAD(expired);
+
+	spin_lock(&hb->chain_lock);
+
+	hlist_for_each_entry_safe(fq, n, &hb->chain, list) {
+		if (!inet_fragq_should_evict(fq))
+			continue;
+
+		if (!del_timer(&fq->timer))
+			continue;
+
+		hlist_add_head(&fq->list_evictor, &expired);
+		++evicted;
+	}
+
+	spin_unlock(&hb->chain_lock);
+
+	hlist_for_each_entry_safe(fq, n, &expired, list_evictor)
+		f->frag_expire((unsigned long) fq);
+
+	return evicted;
+}
+
+static void inet_frag_worker(struct work_struct *work)
+{
+	unsigned int budget = INETFRAGS_EVICT_BUCKETS;
+	unsigned int i, evicted = 0;
+	struct inet_frags *f;
+
+	f = container_of(work, struct inet_frags, frags_work);
+
+	BUILD_BUG_ON(INETFRAGS_EVICT_BUCKETS >= INETFRAGS_HASHSZ);
+
+	local_bh_disable();
+
+	for (i = ACCESS_ONCE(f->next_bucket); budget; --budget) {
+		evicted += inet_evict_bucket(f, &f->hash[i]);
+		i = (i + 1) & (INETFRAGS_HASHSZ - 1);
+		if (evicted > INETFRAGS_EVICT_MAX)
+			break;
 	}
-	write_unlock(&f->lock);
 
-	mod_timer(&f->secret_timer, now + f->secret_interval);
+	f->next_bucket = i;
+
+	local_bh_enable();
+
+	if (f->rebuild && inet_frag_may_rebuild(f))
+		inet_frag_secret_rebuild(f);
+}
+
+static void inet_frag_schedule_worker(struct inet_frags *f)
+{
+	if (unlikely(!work_pending(&f->frags_work)))
+		schedule_work(&f->frags_work);
 }
 
-void inet_frags_init(struct inet_frags *f)
+int inet_frags_init(struct inet_frags *f)
 {
 	int i;
 
+	INIT_WORK(&f->frags_work, inet_frag_worker);
+
 	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)) ^
-				   (jiffies ^ (jiffies >> 6)));
+	seqlock_init(&f->rnd_seqlock);
+	f->last_rebuild_jiffies = 0;
+	f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
+					    NULL);
+	if (!f->frags_cachep)
+		return -ENOMEM;
 
-	setup_timer(&f->secret_timer, inet_frag_secret_rebuild,
-			(unsigned long)f);
-	f->secret_timer.expires = jiffies + f->secret_interval;
-	add_timer(&f->secret_timer);
+	return 0;
 }
 EXPORT_SYMBOL(inet_frags_init);
 
-void inet_frags_init_net(struct netns_frags *nf)
-{
-	nf->nqueues = 0;
-	init_frag_mem_limit(nf);
-	INIT_LIST_HEAD(&nf->lru_list);
-	spin_lock_init(&nf->lru_lock);
-}
-EXPORT_SYMBOL(inet_frags_init_net);
-
 void inet_frags_fini(struct inet_frags *f)
 {
-	del_timer(&f->secret_timer);
+	cancel_work_sync(&f->frags_work);
+	kmem_cache_destroy(f->frags_cachep);
 }
 EXPORT_SYMBOL(inet_frags_fini);
 
 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
 {
+	unsigned int seq;
+	int i;
+
 	nf->low_thresh = 0;
 
+evict_again:
 	local_bh_disable();
-	inet_frag_evictor(nf, f, true);
+	seq = read_seqbegin(&f->rnd_seqlock);
+
+	for (i = 0; i < INETFRAGS_HASHSZ ; i++)
+		inet_evict_bucket(f, &f->hash[i]);
+
 	local_bh_enable();
+	cond_resched();
+
+	if (read_seqretry(&f->rnd_seqlock, seq) ||
+	    percpu_counter_sum(&nf->mem))
+		goto evict_again;
 
 	percpu_counter_destroy(&nf->mem);
 }
 EXPORT_SYMBOL(inet_frags_exit_net);
 
-static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
+static struct inet_frag_bucket *
+get_frag_bucket_locked(struct inet_frag_queue *fq, struct inet_frags *f)
+__acquires(hb->chain_lock)
 {
 	struct inet_frag_bucket *hb;
-	unsigned int hash;
+	unsigned int seq, hash;
+
+ restart:
+	seq = read_seqbegin(&f->rnd_seqlock);
 
-	read_lock(&f->lock);
-	hash = f->hashfn(fq);
+	hash = inet_frag_hashfn(f, fq);
 	hb = &f->hash[hash];
 
 	spin_lock(&hb->chain_lock);
+	if (read_seqretry(&f->rnd_seqlock, seq)) {
+		spin_unlock(&hb->chain_lock);
+		goto restart;
+	}
+
+	return hb;
+}
+
+static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
+{
+	struct inet_frag_bucket *hb;
+
+	hb = get_frag_bucket_locked(fq, f);
 	hlist_del(&fq->list);
+	fq->flags |= INET_FRAG_COMPLETE;
 	spin_unlock(&hb->chain_lock);
-
-	read_unlock(&f->lock);
-	inet_frag_lru_del(fq);
 }
 
 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
@@ -152,30 +278,28 @@
 	if (del_timer(&fq->timer))
 		atomic_dec(&fq->refcnt);
 
-	if (!(fq->last_in & INET_FRAG_COMPLETE)) {
+	if (!(fq->flags & INET_FRAG_COMPLETE)) {
 		fq_unlink(fq, f);
 		atomic_dec(&fq->refcnt);
-		fq->last_in |= INET_FRAG_COMPLETE;
 	}
 }
 EXPORT_SYMBOL(inet_frag_kill);
 
 static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f,
-		struct sk_buff *skb)
+				  struct sk_buff *skb)
 {
 	if (f->skb_free)
 		f->skb_free(skb);
 	kfree_skb(skb);
 }
 
-void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
-					int *work)
+void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f)
 {
 	struct sk_buff *fp;
 	struct netns_frags *nf;
 	unsigned int sum, sum_truesize = 0;
 
-	WARN_ON(!(q->last_in & INET_FRAG_COMPLETE));
+	WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
 	WARN_ON(del_timer(&q->timer) != 0);
 
 	/* Release all fragment data. */
@@ -189,89 +313,33 @@
 		fp = xp;
 	}
 	sum = sum_truesize + f->qsize;
-	if (work)
-		*work -= sum;
-	sub_frag_mem_limit(q, sum);
 
 	if (f->destructor)
 		f->destructor(q);
-	kfree(q);
+	kmem_cache_free(f->frags_cachep, q);
 
+	sub_frag_mem_limit(nf, sum);
 }
 EXPORT_SYMBOL(inet_frag_destroy);
 
-int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force)
-{
-	struct inet_frag_queue *q;
-	int work, evicted = 0;
-
-	if (!force) {
-		if (frag_mem_limit(nf) <= nf->high_thresh)
-			return 0;
-	}
-
-	work = frag_mem_limit(nf) - nf->low_thresh;
-	while (work > 0 || force) {
-		spin_lock(&nf->lru_lock);
-
-		if (list_empty(&nf->lru_list)) {
-			spin_unlock(&nf->lru_lock);
-			break;
-		}
-
-		q = list_first_entry(&nf->lru_list,
-				struct inet_frag_queue, lru_list);
-		atomic_inc(&q->refcnt);
-		/* Remove q from list to avoid several CPUs grabbing it */
-		list_del_init(&q->lru_list);
-
-		spin_unlock(&nf->lru_lock);
-
-		spin_lock(&q->lock);
-		if (!(q->last_in & INET_FRAG_COMPLETE))
-			inet_frag_kill(q, f);
-		spin_unlock(&q->lock);
-
-		if (atomic_dec_and_test(&q->refcnt))
-			inet_frag_destroy(q, f, &work);
-		evicted++;
-	}
-
-	return evicted;
-}
-EXPORT_SYMBOL(inet_frag_evictor);
-
 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_queue *qp_in,
+						struct inet_frags *f,
+						void *arg)
 {
-	struct inet_frag_bucket *hb;
+	struct inet_frag_bucket *hb = get_frag_bucket_locked(qp_in, f);
 	struct inet_frag_queue *qp;
-#ifdef CONFIG_SMP
-#endif
-	unsigned int hash;
-
-	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
-	 * released the hash bucket lock.
+	 * such entry could have been created on other cpu before
+	 * we acquired hash bucket lock.
 	 */
 	hlist_for_each_entry(qp, &hb->chain, list) {
 		if (qp->net == nf && f->match(qp, arg)) {
 			atomic_inc(&qp->refcnt);
 			spin_unlock(&hb->chain_lock);
-			read_unlock(&f->lock);
-			qp_in->last_in |= INET_FRAG_COMPLETE;
+			qp_in->flags |= INET_FRAG_COMPLETE;
 			inet_frag_put(qp_in, f);
 			return qp;
 		}
@@ -283,54 +351,63 @@
 
 	atomic_inc(&qp->refcnt);
 	hlist_add_head(&qp->list, &hb->chain);
-	inet_frag_lru_add(nf, qp);
+
 	spin_unlock(&hb->chain_lock);
-	read_unlock(&f->lock);
 
 	return qp;
 }
 
 static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
-		struct inet_frags *f, void *arg)
+					       struct inet_frags *f,
+					       void *arg)
 {
 	struct inet_frag_queue *q;
 
-	q = kzalloc(f->qsize, GFP_ATOMIC);
-	if (q == NULL)
+	if (frag_mem_limit(nf) > nf->high_thresh) {
+		inet_frag_schedule_worker(f);
+		return NULL;
+	}
+
+	q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
+	if (!q)
 		return NULL;
 
 	q->net = nf;
 	f->constructor(q, arg);
-	add_frag_mem_limit(q, f->qsize);
+	add_frag_mem_limit(nf, f->qsize);
 
 	setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
 	spin_lock_init(&q->lock);
 	atomic_set(&q->refcnt, 1);
-	INIT_LIST_HEAD(&q->lru_list);
 
 	return q;
 }
 
 static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
-		struct inet_frags *f, void *arg)
+						struct inet_frags *f,
+						void *arg)
 {
 	struct inet_frag_queue *q;
 
 	q = inet_frag_alloc(nf, f, arg);
-	if (q == NULL)
+	if (!q)
 		return NULL;
 
 	return inet_frag_intern(nf, q, f, arg);
 }
 
 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_frags *f, void *key,
+				       unsigned int hash)
 {
 	struct inet_frag_bucket *hb;
 	struct inet_frag_queue *q;
 	int depth = 0;
 
+	if (frag_mem_limit(nf) > nf->low_thresh)
+		inet_frag_schedule_worker(f);
+
+	hash &= (INETFRAGS_HASHSZ - 1);
 	hb = &f->hash[hash];
 
 	spin_lock(&hb->chain_lock);
@@ -338,18 +415,22 @@
 		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)
 		return inet_frag_create(nf, f, key);
-	else
-		return ERR_PTR(-ENOBUFS);
+
+	if (inet_frag_may_rebuild(f)) {
+		if (!f->rebuild)
+			f->rebuild = true;
+		inet_frag_schedule_worker(f);
+	}
+
+	return ERR_PTR(-ENOBUFS);
 }
 EXPORT_SYMBOL(inet_frag_find);
 
@@ -361,6 +442,6 @@
 		". Dropping fragment.\n";
 
 	if (PTR_ERR(q) == -ENOBUFS)
-		LIMIT_NETDEBUG(KERN_WARNING "%s%s", prefix, msg);
+		net_dbg_ratelimited("%s%s", prefix, msg);
 }
 EXPORT_SYMBOL(inet_frag_maybe_warn_overflow);