From: Andrey Ignatov <rdna@fb.com>
To: <bpf@vger.kernel.org>
Cc: Andrey Ignatov <rdna@fb.com>, <ast@kernel.org>,
<daniel@iogearbox.net>, <kafai@fb.com>, <andriin@fb.com>,
<kernel-team@fb.com>
Subject: [PATCH v3 bpf-next 1/6] bpf: Simplify __cgroup_bpf_attach
Date: Wed, 18 Dec 2019 17:55:58 -0800 [thread overview]
Message-ID: <c6193db6fe630797110b0d3ff06c125d093b834c.1576720240.git.rdna@fb.com> (raw)
In-Reply-To: <cover.1576720240.git.rdna@fb.com>
__cgroup_bpf_attach has a lot of identical code to handle two scenarios:
BPF_F_ALLOW_MULTI is set and unset.
Simplify it by splitting the two main steps:
* First, the decision is made whether a new bpf_prog_list entry should
be allocated or existing entry should be reused for the new program.
This decision is saved in replace_pl pointer;
* Next, replace_pl pointer is used to handle both possible states of
BPF_F_ALLOW_MULTI flag (set / unset) instead of doing similar work for
them separately.
This splitting, in turn, allows to make further simplifications:
* The check for attaching same program twice in BPF_F_ALLOW_MULTI mode
can be done before allocating cgroup storage, so that if user tries to
attach same program twice no alloc/free happens as it was before;
* pl_was_allocated becomes redundant so it's removed.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
kernel/bpf/cgroup.c | 62 +++++++++++++++++----------------------------
1 file changed, 23 insertions(+), 39 deletions(-)
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 9f90d3c92bda..e8cbdd1be687 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -295,9 +295,8 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
struct bpf_prog *old_prog = NULL;
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE],
*old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {NULL};
+ struct bpf_prog_list *pl, *replace_pl = NULL;
enum bpf_cgroup_storage_type stype;
- struct bpf_prog_list *pl;
- bool pl_was_allocated;
int err;
if ((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI))
@@ -317,6 +316,16 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
return -E2BIG;
+ if (flags & BPF_F_ALLOW_MULTI) {
+ list_for_each_entry(pl, progs, node) {
+ if (pl->prog == prog)
+ /* disallow attaching the same prog twice */
+ return -EINVAL;
+ }
+ } else if (!list_empty(progs)) {
+ replace_pl = list_first_entry(progs, typeof(*pl), node);
+ }
+
for_each_cgroup_storage_type(stype) {
storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
if (IS_ERR(storage[stype])) {
@@ -327,52 +336,27 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
}
}
- if (flags & BPF_F_ALLOW_MULTI) {
- list_for_each_entry(pl, progs, node) {
- if (pl->prog == prog) {
- /* disallow attaching the same prog twice */
- for_each_cgroup_storage_type(stype)
- bpf_cgroup_storage_free(storage[stype]);
- return -EINVAL;
- }
+ if (replace_pl) {
+ pl = replace_pl;
+ old_prog = pl->prog;
+ for_each_cgroup_storage_type(stype) {
+ old_storage[stype] = pl->storage[stype];
+ bpf_cgroup_storage_unlink(old_storage[stype]);
}
-
+ } else {
pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) {
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_free(storage[stype]);
return -ENOMEM;
}
-
- pl_was_allocated = true;
- pl->prog = prog;
- for_each_cgroup_storage_type(stype)
- pl->storage[stype] = storage[stype];
list_add_tail(&pl->node, progs);
- } else {
- if (list_empty(progs)) {
- pl = kmalloc(sizeof(*pl), GFP_KERNEL);
- if (!pl) {
- for_each_cgroup_storage_type(stype)
- bpf_cgroup_storage_free(storage[stype]);
- return -ENOMEM;
- }
- pl_was_allocated = true;
- list_add_tail(&pl->node, progs);
- } else {
- pl = list_first_entry(progs, typeof(*pl), node);
- old_prog = pl->prog;
- for_each_cgroup_storage_type(stype) {
- old_storage[stype] = pl->storage[stype];
- bpf_cgroup_storage_unlink(old_storage[stype]);
- }
- pl_was_allocated = false;
- }
- pl->prog = prog;
- for_each_cgroup_storage_type(stype)
- pl->storage[stype] = storage[stype];
}
+ pl->prog = prog;
+ for_each_cgroup_storage_type(stype)
+ pl->storage[stype] = storage[stype];
+
cgrp->bpf.flags[type] = flags;
err = update_effective_progs(cgrp, type);
@@ -401,7 +385,7 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
pl->storage[stype] = old_storage[stype];
bpf_cgroup_storage_link(old_storage[stype], cgrp, type);
}
- if (pl_was_allocated) {
+ if (!replace_pl) {
list_del(&pl->node);
kfree(pl);
}
--
2.17.1
next prev parent reply other threads:[~2019-12-19 2:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 1:55 [PATCH v3 bpf-next 0/6] bpf: Support replacing cgroup-bpf program in MULTI mode Andrey Ignatov
2019-12-19 1:55 ` Andrey Ignatov [this message]
2019-12-19 1:55 ` [PATCH v3 bpf-next 2/6] bpf: Remove unused new_flags in hierarchy_allows_attach() Andrey Ignatov
2019-12-19 1:56 ` [PATCH v3 bpf-next 3/6] bpf: Support replacing cgroup-bpf program in MULTI mode Andrey Ignatov
2019-12-19 1:56 ` [PATCH v3 bpf-next 4/6] libbpf: Introduce bpf_prog_attach_xattr Andrey Ignatov
2019-12-19 5:49 ` Andrii Nakryiko
2019-12-19 7:03 ` Andrey Ignatov
2019-12-19 1:56 ` [PATCH v3 bpf-next 5/6] selftests/bpf: Convert test_cgroup_attach to prog_tests Andrey Ignatov
2019-12-19 6:11 ` Andrii Nakryiko
2019-12-19 7:20 ` Andrey Ignatov
2019-12-19 20:40 ` Andrii Nakryiko
2019-12-19 1:56 ` [PATCH v3 bpf-next 6/6] selftests/bpf: Test BPF_F_REPLACE in cgroup_attach_multi Andrey Ignatov
2019-12-19 5:58 ` Andrii Nakryiko
2019-12-19 7:35 ` Andrey Ignatov
2019-12-19 20:44 ` Andrii Nakryiko
2019-12-19 21:09 ` Andrey Ignatov
2019-12-19 21:19 ` Andrii Nakryiko
2019-12-19 21:25 ` Andrey Ignatov
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