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authorDavid S. Miller <davem@davemloft.net>2020-02-19 16:42:35 -0800
committerDavid S. Miller <davem@davemloft.net>2020-02-19 16:42:35 -0800
commit41f57cfde186dba6e357f9db25eafbed017e4487 (patch)
treee5f3ab80902a1f921341d7846fbe956695fda351 /kernel
parentfca07a937a27e720df7310bc5e68a11e5d2ff3c5 (diff)
parentb9aff38de2cb166476988020428985c5f7412ffc (diff)
downloadlinux-41f57cfde186dba6e357f9db25eafbed017e4487.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/btf.c6
-rw-r--r--kernel/bpf/hashtab.c58
-rw-r--r--kernel/bpf/offload.c2
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)) {