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From:   Roman Gushchin <guro@fb.com>
To:     <bpf@vger.kernel.org>
CC:     <ast@kernel.org>, <daniel@iogearbox.net>, <netdev@vger.kernel.org>,
        <andrii@kernel.org>, <akpm@linux-foundation.org>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <kernel-team@fb.com>
Subject: [PATCH bpf-next v9 27/34] bpf: eliminate rlimit-based memory accounting for bpf ringbuffer
Date:   Tue, 1 Dec 2020 13:58:53 -0800
Message-ID: <20201201215900.3569844-28-guro@fb.com>
In-Reply-To: <20201201215900.3569844-1-guro@fb.com>
References: <20201201215900.3569844-1-guro@fb.com>
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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>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
---
 kernel/bpf/ringbuf.c | 24 ++++--------------------
 1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 8983a46f6580..f25b719ac786 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -48,7 +48,6 @@ struct bpf_ringbuf {
=20
 struct bpf_ringbuf_map {
 	struct bpf_map map;
-	struct bpf_map_memory memory;
 	struct bpf_ringbuf *rb;
 };
=20
@@ -131,7 +130,7 @@ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t d=
ata_sz, int numa_node)
=20
 	rb =3D bpf_ringbuf_area_alloc(data_sz, numa_node);
 	if (!rb)
-		return ERR_PTR(-ENOMEM);
+		return NULL;
=20
 	spin_lock_init(&rb->spinlock);
 	init_waitqueue_head(&rb->waitq);
@@ -147,8 +146,6 @@ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t d=
ata_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;
=20
 	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)
=20
 	bpf_map_init_from_attr(&rb_map->map, attr);
=20
-	cost =3D sizeof(struct bpf_ringbuf_map) +
-	       sizeof(struct bpf_ringbuf) +
-	       attr->max_entries;
-	err =3D bpf_map_charge_init(&rb_map->map.memory, cost);
-	if (err)
-		goto err_free_map;
-
 	rb_map->rb =3D bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_no=
de);
-	if (IS_ERR(rb_map->rb)) {
-		err =3D PTR_ERR(rb_map->rb);
-		goto err_uncharge;
+	if (!rb_map->rb) {
+		kfree(rb_map);
+		return ERR_PTR(-ENOMEM);
 	}
=20
 	return &rb_map->map;
-
-err_uncharge:
-	bpf_map_charge_finish(&rb_map->map.memory);
-err_free_map:
-	kfree(rb_map);
-	return ERR_PTR(err);
 }
=20
 static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
--=20
2.26.2