Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Alexei Starovoitov says:

====================
pull-request: bpf 2020-02-19

The following pull-request contains BPF updates for your *net* tree.

We've added 10 non-merge commits during the last 10 day(s) which contain
a total of 10 files changed, 93 insertions(+), 31 deletions(-).

The main changes are:

1) batched bpf hashtab fixes from Brian and Yonghong.

2) various selftests and libbpf fixes.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 57 insertions, 9 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 805c43b083e9..787140095e58 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4142,9 +4142,9 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
  * EFAULT - verifier bug
  * 0 - 99% match. The last 1% is validated by the verifier.
  */
-int btf_check_func_type_match(struct bpf_verifier_log *log,
-			      struct btf *btf1, const struct btf_type *t1,
-			      struct btf *btf2, const struct btf_type *t2)
+static int btf_check_func_type_match(struct bpf_verifier_log *log,
+				     struct btf *btf1, const struct btf_type *t1,
+				     struct btf *btf2, const struct btf_type *t2)
 {
 	const struct btf_param *args1, *args2;
 	const char *fn1, *fn2, *s1, *s2;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 2d182c4ee9d9..a1468e3f5af2 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -56,6 +56,7 @@ struct htab_elem {
 			union {
 				struct bpf_htab *htab;
 				struct pcpu_freelist_node fnode;
+				struct htab_elem *batch_flink;
 			};
 		};
 	};
@@ -126,6 +127,17 @@ free_elems:
 	bpf_map_area_free(htab->elems);
 }
 
+/* The LRU list has a lock (lru_lock). Each htab bucket has a lock
+ * (bucket_lock). If both locks need to be acquired together, the lock
+ * order is always lru_lock -> bucket_lock and this only happens in
+ * bpf_lru_list.c logic. For example, certain code path of
+ * bpf_lru_pop_free(), which is called by function prealloc_lru_pop(),
+ * will acquire lru_lock first followed by acquiring bucket_lock.
+ *
+ * In hashtab.c, to avoid deadlock, lock acquisition of
+ * bucket_lock followed by lru_lock is not allowed. In such cases,
+ * bucket_lock needs to be released first before acquiring lru_lock.
+ */
 static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
 					  u32 hash)
 {
@@ -1256,10 +1268,12 @@ __htab_map_lookup_and_delete_batch(struct bpf_map *map,
 	void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
 	void *ubatch = u64_to_user_ptr(attr->batch.in_batch);
 	u32 batch, max_count, size, bucket_size;
+	struct htab_elem *node_to_free = NULL;
 	u64 elem_map_flags, map_flags;
 	struct hlist_nulls_head *head;
 	struct hlist_nulls_node *n;
-	unsigned long flags;
+	unsigned long flags = 0;
+	bool locked = false;
 	struct htab_elem *l;
 	struct bucket *b;
 	int ret = 0;
@@ -1319,15 +1333,25 @@ again_nocopy:
 	dst_val = values;
 	b = &htab->buckets[batch];
 	head = &b->head;
-	raw_spin_lock_irqsave(&b->lock, flags);
+	/* do not grab the lock unless need it (bucket_cnt > 0). */
+	if (locked)
+		raw_spin_lock_irqsave(&b->lock, flags);
 
 	bucket_cnt = 0;
 	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
 		bucket_cnt++;
 
+	if (bucket_cnt && !locked) {
+		locked = true;
+		goto again_nocopy;
+	}
+
 	if (bucket_cnt > (max_count - total)) {
 		if (total == 0)
 			ret = -ENOSPC;
+		/* Note that since bucket_cnt > 0 here, it is implicit
+		 * that the locked was grabbed, so release it.
+		 */
 		raw_spin_unlock_irqrestore(&b->lock, flags);
 		rcu_read_unlock();
 		this_cpu_dec(bpf_prog_active);
@@ -1337,6 +1361,9 @@ again_nocopy:
 
 	if (bucket_cnt > bucket_size) {
 		bucket_size = bucket_cnt;
+		/* Note that since bucket_cnt > 0 here, it is implicit
+		 * that the locked was grabbed, so release it.
+		 */
 		raw_spin_unlock_irqrestore(&b->lock, flags);
 		rcu_read_unlock();
 		this_cpu_dec(bpf_prog_active);
@@ -1346,6 +1373,10 @@ again_nocopy:
 		goto alloc;
 	}
 
+	/* Next block is only safe to run if you have grabbed the lock */
+	if (!locked)
+		goto next_batch;
+
 	hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
 		memcpy(dst_key, l->key, key_size);
 
@@ -1370,16 +1401,33 @@ again_nocopy:
 		}
 		if (do_delete) {
 			hlist_nulls_del_rcu(&l->hash_node);
-			if (is_lru_map)
-				bpf_lru_push_free(&htab->lru, &l->lru_node);
-			else
+
+			/* bpf_lru_push_free() will acquire lru_lock, which
+			 * may cause deadlock. See comments in function
+			 * prealloc_lru_pop(). Let us do bpf_lru_push_free()
+			 * after releasing the bucket lock.
+			 */
+			if (is_lru_map) {
+				l->batch_flink = node_to_free;
+				node_to_free = l;
+			} else {
 				free_htab_elem(htab, l);
+			}
 		}
 		dst_key += key_size;
 		dst_val += value_size;
 	}
 
 	raw_spin_unlock_irqrestore(&b->lock, flags);
+	locked = false;
+
+	while (node_to_free) {
+		l = node_to_free;
+		node_to_free = node_to_free->batch_flink;
+		bpf_lru_push_free(&htab->lru, &l->lru_node);
+	}
+
+next_batch:
 	/* If we are not copying data, we can go to next bucket and avoid
 	 * unlocking the rcu.
 	 */
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index 2c5dc6541ece..bd09290e3648 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -321,7 +321,7 @@ int bpf_prog_offload_info_fill(struct bpf_prog_info *info,
 
 	ulen = info->jited_prog_len;
 	info->jited_prog_len = aux->offload->jited_len;
-	if (info->jited_prog_len & ulen) {
+	if (info->jited_prog_len && ulen) {
 		uinsns = u64_to_user_ptr(info->jited_prog_insns);
 		ulen = min_t(u32, info->jited_prog_len, ulen);
 		if (copy_to_user(uinsns, aux->offload->jited_image, ulen)) {