> On Feb 25, 2020, at 9:08 AM, Martin Lau <kafai@xxxxxx> 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@xxxxxx> 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@xxxxxx>
[...]
>
>>> @@ -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@xxxxxx>
