X-Git-Url: http://git.cascardo.eti.br/?a=blobdiff_plain;f=kernel%2Fbpf%2Fhashtab.c;h=570eeca7bdfa79ce16d18ee94fac64c40aa11d38;hb=e8f0f8aa4eb356bd729f15be8827db2558ea1ae6;hp=fff3650d52fc774f7efdf2d289e879a916f44c60;hpb=85bd5ac371c844f66918dda8c83145a26a55f9f2;p=cascardo%2Flinux.git

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index fff3650d52fc..570eeca7bdfa 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -26,11 +26,18 @@ struct bpf_htab {
 	struct bucket *buckets;
 	void *elems;
 	struct pcpu_freelist freelist;
+	void __percpu *extra_elems;
 	atomic_t count;	/* number of elements in this hashtable */
 	u32 n_buckets;	/* number of hash buckets */
 	u32 elem_size;	/* size of each element in bytes */
 };
 
+enum extra_elem_state {
+	HTAB_NOT_AN_EXTRA_ELEM = 0,
+	HTAB_EXTRA_ELEM_FREE,
+	HTAB_EXTRA_ELEM_USED
+};
+
 /* each htab element is struct htab_elem + key + value */
 struct htab_elem {
 	union {
@@ -38,7 +45,10 @@ struct htab_elem {
 		struct bpf_htab *htab;
 		struct pcpu_freelist_node fnode;
 	};
-	struct rcu_head rcu;
+	union {
+		struct rcu_head rcu;
+		enum extra_elem_state state;
+	};
 	u32 hash;
 	char key[0] __aligned(8);
 };
@@ -113,6 +123,23 @@ free_elems:
 	return err;
 }
 
+static int alloc_extra_elems(struct bpf_htab *htab)
+{
+	void __percpu *pptr;
+	int cpu;
+
+	pptr = __alloc_percpu_gfp(htab->elem_size, 8, GFP_USER | __GFP_NOWARN);
+	if (!pptr)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		((struct htab_elem *)per_cpu_ptr(pptr, cpu))->state =
+			HTAB_EXTRA_ELEM_FREE;
+	}
+	htab->extra_elems = pptr;
+	return 0;
+}
+
 /* Called from syscall */
 static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 {
@@ -185,6 +212,8 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 	if (percpu)
 		cost += (u64) round_up(htab->map.value_size, 8) *
 			num_possible_cpus() * htab->map.max_entries;
+	else
+	       cost += (u64) htab->elem_size * num_possible_cpus();
 
 	if (cost >= U32_MAX - PAGE_SIZE)
 		/* make sure page count doesn't overflow */
@@ -212,14 +241,22 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 		raw_spin_lock_init(&htab->buckets[i].lock);
 	}
 
+	if (!percpu) {
+		err = alloc_extra_elems(htab);
+		if (err)
+			goto free_buckets;
+	}
+
 	if (!(attr->map_flags & BPF_F_NO_PREALLOC)) {
 		err = prealloc_elems_and_freelist(htab);
 		if (err)
-			goto free_buckets;
+			goto free_extra_elems;
 	}
 
 	return &htab->map;
 
+free_extra_elems:
+	free_percpu(htab->extra_elems);
 free_buckets:
 	kvfree(htab->buckets);
 free_htab:
@@ -349,7 +386,6 @@ static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
 	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
 		free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
 	kfree(l);
-
 }
 
 static void htab_elem_free_rcu(struct rcu_head *head)
@@ -370,6 +406,11 @@ static void htab_elem_free_rcu(struct rcu_head *head)
 
 static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
 {
+	if (l->state == HTAB_EXTRA_ELEM_USED) {
+		l->state = HTAB_EXTRA_ELEM_FREE;
+		return;
+	}
+
 	if (!(htab->map.map_flags & BPF_F_NO_PREALLOC)) {
 		pcpu_freelist_push(&htab->freelist, &l->fnode);
 	} else {
@@ -381,25 +422,44 @@ static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
 
 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 					 void *value, u32 key_size, u32 hash,
-					 bool percpu, bool onallcpus)
+					 bool percpu, bool onallcpus,
+					 bool old_elem_exists)
 {
 	u32 size = htab->map.value_size;
 	bool prealloc = !(htab->map.map_flags & BPF_F_NO_PREALLOC);
 	struct htab_elem *l_new;
 	void __percpu *pptr;
+	int err = 0;
 
 	if (prealloc) {
 		l_new = (struct htab_elem *)pcpu_freelist_pop(&htab->freelist);
 		if (!l_new)
-			return ERR_PTR(-E2BIG);
+			err = -E2BIG;
 	} else {
 		if (atomic_inc_return(&htab->count) > htab->map.max_entries) {
 			atomic_dec(&htab->count);
-			return ERR_PTR(-E2BIG);
+			err = -E2BIG;
+		} else {
+			l_new = kmalloc(htab->elem_size,
+					GFP_ATOMIC | __GFP_NOWARN);
+			if (!l_new)
+				return ERR_PTR(-ENOMEM);
 		}
-		l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN);
-		if (!l_new)
-			return ERR_PTR(-ENOMEM);
+	}
+
+	if (err) {
+		if (!old_elem_exists)
+			return ERR_PTR(err);
+
+		/* if we're updating the existing element and the hash table
+		 * is full, use per-cpu extra elems
+		 */
+		l_new = this_cpu_ptr(htab->extra_elems);
+		if (l_new->state != HTAB_EXTRA_ELEM_FREE)
+			return ERR_PTR(-E2BIG);
+		l_new->state = HTAB_EXTRA_ELEM_USED;
+	} else {
+		l_new->state = HTAB_NOT_AN_EXTRA_ELEM;
 	}
 
 	memcpy(l_new->key, key, key_size);
@@ -489,7 +549,8 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
 	if (ret)
 		goto err;
 
-	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false);
+	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
+				!!l_old);
 	if (IS_ERR(l_new)) {
 		/* all pre-allocated elements are in use or memory exhausted */
 		ret = PTR_ERR(l_new);
@@ -563,7 +624,7 @@ static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
 		}
 	} else {
 		l_new = alloc_htab_elem(htab, key, value, key_size,
-					hash, true, onallcpus);
+					hash, true, onallcpus, false);
 		if (IS_ERR(l_new)) {
 			ret = PTR_ERR(l_new);
 			goto err;
@@ -652,6 +713,7 @@ static void htab_map_free(struct bpf_map *map)
 		htab_free_elems(htab);
 		pcpu_freelist_destroy(&htab->freelist);
 	}
+	free_percpu(htab->extra_elems);
 	kvfree(htab->buckets);
 	kfree(htab);
 }