bpf: Eliminate rlimit-based memory accounting for bpf ringbuffer

Do not use rlimit-based memory accounting for bpf ringbuffer.
It has been replaced with the memcg-based memory accounting.

bpf_ringbuf_alloc() can't return anything except ERR_PTR(-ENOMEM)
and a valid pointer, so to simplify the code make it return NULL
in the first case. This allows to drop a couple of lines in
ringbuf_map_alloc() and also makes it look similar to other memory
allocating function like kmalloc().

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20201201215900.3569844-28-guro@fb.com

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 8983a46f6580173774dc436adbe828403bbcdd3f..f25b719ac786811c8d1f06b849e42422ccfba70e 100644 (file)
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -48,7 +48,6 @@ struct bpf_ringbuf {
 
 struct bpf_ringbuf_map {
        struct bpf_map map;
-       struct bpf_map_memory memory;
        struct bpf_ringbuf *rb;
 };
 
@@ -131,7 +130,7 @@ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
 
        rb = bpf_ringbuf_area_alloc(data_sz, numa_node);
        if (!rb)
-               return ERR_PTR(-ENOMEM);
+               return NULL;
 
        spin_lock_init(&rb->spinlock);
        init_waitqueue_head(&rb->waitq);
@@ -147,8 +146,6 @@ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
 static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
 {
        struct bpf_ringbuf_map *rb_map;
-       u64 cost;
-       int err;
 
        if (attr->map_flags & ~RINGBUF_CREATE_FLAG_MASK)
                return ERR_PTR(-EINVAL);
@@ -170,26 +167,13 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
 
        bpf_map_init_from_attr(&rb_map->map, attr);
 
-       cost = sizeof(struct bpf_ringbuf_map) +
-              sizeof(struct bpf_ringbuf) +
-              attr->max_entries;
-       err = bpf_map_charge_init(&rb_map->map.memory, cost);
-       if (err)
-               goto err_free_map;
-
        rb_map->rb = bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_node);
-       if (IS_ERR(rb_map->rb)) {
-               err = PTR_ERR(rb_map->rb);
-               goto err_uncharge;
+       if (!rb_map->rb) {
+               kfree(rb_map);
+               return ERR_PTR(-ENOMEM);
        }
 
        return &rb_map->map;
-
-err_uncharge:
-       bpf_map_charge_finish(&rb_map->map.memory);
-err_free_map:
-       kfree(rb_map);
-       return ERR_PTR(err);
 }
 
 static void bpf_ringbuf_free(struct bpf_ringbuf *rb)