netdev - Re: [PATCH bpf 1/2] net: introduce __sk_rmem

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Date: Fri, 28 Jul 2023 20:36:49 +0800
From: "liujian (CE)" <liujian56@...wei.com>
To: John Fastabend <john.fastabend@...il.com>, Eric Dumazet
	<edumazet@...gle.com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<jakub@...udflare.com>, <dsahern@...nel.org>, <ast@...nel.org>,
	<daniel@...earbox.net>, <netdev@...r.kernel.org>, <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf 1/2] net: introduce __sk_rmem_schedule() helper



On 2023/7/28 3:16, John Fastabend wrote:
> Eric Dumazet wrote:
>> On Wed, Jul 26, 2023 at 4:15 PM Liu Jian <liujian56@...wei.com> wrote:
>>>
>>> Compared with sk_wmem_schedule(), sk_rmem_schedule() not only performs
>>> rmem accounting, but also checks skb_pfmemalloc. The __sk_rmem_schedule()
>>> helper function is introduced here to perform only rmem accounting related
>>> activities.
>>>
>>
>> Why not care about pfmemalloc ? Why is it safe ?
>>
>> You need to give more details, or simply reuse the existing helper.
I didn't think so much. I extracted this helper just to do rmem 
accounting in bpf_tcp_ingress(), because I didn't see the pfmemalloc 
flag set when alloc sk_msg in sk_msg_alloc(). And thanks for your review.
> 
> I would just use the existing helper. Seems it should be fine.
ok, let's just leave it as it is. Thanks John.
> 
>>
>>> Signed-off-by: Liu Jian <liujian56@...wei.com>
>>> ---
>>>   include/net/sock.h | 12 ++++++++----
>>>   1 file changed, 8 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/include/net/sock.h b/include/net/sock.h
>>> index 2eb916d1ff64..58bf26c5c041 100644
>>> --- a/include/net/sock.h
>>> +++ b/include/net/sock.h
>>> @@ -1617,16 +1617,20 @@ static inline bool sk_wmem_schedule(struct sock *sk, int size)
>>>          return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_SEND);
>>>   }
>>>
>>> -static inline bool
>>> -sk_rmem_schedule(struct sock *sk, struct sk_buff *skb, int size)
>>> +static inline bool __sk_rmem_schedule(struct sock *sk, int size)
>>>   {
>>>          int delta;
>>>
>>>          if (!sk_has_account(sk))
>>>                  return true;
>>>          delta = size - sk->sk_forward_alloc;
>>> -       return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_RECV) ||
>>> -               skb_pfmemalloc(skb);
>>> +       return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_RECV);
>>> +}
>>> +
>>> +static inline bool
>>> +sk_rmem_schedule(struct sock *sk, struct sk_buff *skb, int size)
>>> +{
>>> +       return __sk_rmem_schedule(sk, size) || skb_pfmemalloc(skb);
>>>   }
>>>
>>>   static inline int sk_unused_reserved_mem(const struct sock *sk)
>>> --
>>> 2.34.1
>>>
> 
>