From: Song Liu <songliubraving@fb.com>
To: Martin Lau <kafai@fb.com>
Cc: Song Liu <song@kernel.org>, bpf <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
David Miller <davem@davemloft.net>,
Kernel Team <Kernel-team@fb.com>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next 4/4] bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump()
Date: Tue, 25 Feb 2020 17:11:09 +0000 [thread overview]
Message-ID: <7BD5CBDC-840B-404C-9992-AAE94190E8E2@fb.com> (raw)
In-Reply-To: <20200225170824.dhwkw2ojzsfz223k@kafai-mbp>
> On Feb 25, 2020, at 9:08 AM, Martin Lau <kafai@fb.com> wrote:
>
> On Mon, Feb 24, 2020 at 09:47:33PM -0800, Song Liu wrote:
>> On Fri, Feb 21, 2020 at 10:49 AM Martin KaFai Lau <kafai@fb.com> wrote:
>>>
>>> This patch will dump out the bpf_sk_storages of a sk
>>> if the request has the INET_DIAG_REQ_SK_BPF_STORAGES nlattr.
>>>
>>> An array of SK_DIAG_BPF_STORAGE_REQ_MAP_FD can be specified in
>>> INET_DIAG_REQ_SK_BPF_STORAGES to select which bpf_sk_storage to dump.
>>> If no map_fd is specified, all bpf_sk_storages of a sk will be dumped.
>> [...]
>>
>>> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
[...]
>
>>> @@ -1022,8 +1069,11 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
>>> const struct inet_diag_req_v2 *r)
>>> {
>>> const struct inet_diag_handler *handler;
>>> + u32 prev_min_dump_alloc;
>>> int err = 0;
>>>
>>> +again:
>>> + prev_min_dump_alloc = cb->min_dump_alloc;
>>> handler = inet_diag_lock_handler(r->sdiag_protocol);
>>> if (!IS_ERR(handler))
>>> handler->dump(skb, cb, r);
>>> @@ -1031,6 +1081,12 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
>>> err = PTR_ERR(handler);
>>> inet_diag_unlock_handler(handler);
>>>
>>> + if (!skb->len && cb->min_dump_alloc > prev_min_dump_alloc) {
>>
>> Why do we check for !skb->len here?
> skb contains the info of sk(s) to be dumped to the userspace.
> It may contain no sk info (i.e. !skb->len), 1 sk info, 2 sk info...etc.
> It only retries if there is no sk info and the cb->min_dump_alloc becomes
> larger (together, it means the current skb is not large enough to fit one
> sk info).
I see. Thanks for the explanation.
Acked-by: Song Liu <songliubraving@fb.com>
prev parent reply other threads:[~2020-02-25 17:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 18:46 [PATCH bpf-next 0/4] Provide bpf_sk_storage data in INET_DIAG Martin KaFai Lau
2020-02-21 18:46 ` [PATCH bpf-next 1/4] inet_diag: Refactor inet_sk_diag_fill(), dump(), and dump_one() Martin KaFai Lau
2020-02-25 0:12 ` Song Liu
2020-02-21 18:47 ` [PATCH bpf-next 2/4] inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data Martin KaFai Lau
2020-02-25 0:37 ` Song Liu
2020-02-21 18:47 ` [PATCH bpf-next 3/4] bpf: INET_DIAG support in bpf_sk_storage Martin KaFai Lau
2020-02-25 5:23 ` Song Liu
2020-02-21 18:47 ` [PATCH bpf-next 4/4] bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump() Martin KaFai Lau
2020-02-25 5:47 ` Song Liu
2020-02-25 17:08 ` Martin KaFai Lau
2020-02-25 17:11 ` Song Liu [this message]
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