From: Eric Dumazet <eric.dumazet@gmail.com>
To: linmiaohe <linmiaohe@huawei.com>, Eric Dumazet <eric.dumazet@gmail.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
"pshelar@ovn.org" <pshelar@ovn.org>,
"martin.varghese@nokia.com" <martin.varghese@nokia.com>,
"fw@strlen.de" <fw@strlen.de>,
"dcaratti@redhat.com" <dcaratti@redhat.com>,
"edumazet@google.com" <edumazet@google.com>,
"steffen.klassert@secunet.com" <steffen.klassert@secunet.com>,
"pabeni@redhat.com" <pabeni@redhat.com>,
"shmulik@metanetworks.com" <shmulik@metanetworks.com>,
"kyk.segfault@gmail.com" <kyk.segfault@gmail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: eliminate meaningless memcpy to data in pskb_carve_inside_nonlinear()
Date: Tue, 11 Aug 2020 08:35:07 -0700 [thread overview]
Message-ID: <9684c26c-9f26-5a7f-3d17-d180afff432c@gmail.com> (raw)
In-Reply-To: <40a0b4ba22ff499686a2521998767ae5@huawei.com>
On 8/11/20 5:10 AM, linmiaohe wrote:
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> On 8/10/20 5:28 AM, Miaohe Lin wrote:
>>> The skb_shared_info part of the data is assigned in the following
>>> loop. It is meaningless to do a memcpy here.
>>>
>>
>> Reminder : net-next is CLOSED.
>>
>
> Thanks for your remind. I would wait for it open.
>
>> This is not correct. We still have to copy _something_
>>
>> Something like :
>>
>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 2828f6d5ba898a5e50ccce45589bf1370e474b0f..1c0519426c7ba4b04377fc8054c4223c135879ab 100644
>> --- a/net/core/skbuff.c
>> +++ b/net/core/skbuff.c
>> @@ -5953,8 +5953,8 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
>> size = SKB_WITH_OVERHEAD(ksize(data));
>>
>> memcpy((struct skb_shared_info *)(data + size),
>> - skb_shinfo(skb), offsetof(struct skb_shared_info,
>> - frags[skb_shinfo(skb)->nr_frags]));
>> + skb_shinfo(skb), offsetof(struct skb_shared_info,
>> + frags[0]));
>> +
>> if (skb_orphan_frags(skb, gfp_mask)) {
>> kfree(data);
>> return -ENOMEM;
>>
>
> This looks good. Will send a patch v2 soon. May I add a suggested-by tag of you ?
I would advise not using Suggested-by, as this would imply I suggested the idea of changing
this function in the first place.
I will add a Reviewed-by: eventually if your v2 submission looks fine to me.
Thanks.
> Many thanks.
>
next prev parent reply other threads:[~2020-08-11 15:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 12:10 [PATCH] net: eliminate meaningless memcpy to data in pskb_carve_inside_nonlinear() linmiaohe
2020-08-11 15:35 ` Eric Dumazet [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-08-11 11:54 linmiaohe
2020-08-10 12:28 Miaohe Lin
2020-08-10 13:56 ` Florian Westphal
2020-08-10 15:06 ` Eric Dumazet
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9684c26c-9f26-5a7f-3d17-d180afff432c@gmail.com \
--to=eric.dumazet@gmail.com \
--cc=davem@davemloft.net \
--cc=dcaratti@redhat.com \
--cc=edumazet@google.com \
--cc=fw@strlen.de \
--cc=kuba@kernel.org \
--cc=kyk.segfault@gmail.com \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.varghese@nokia.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=pshelar@ovn.org \
--cc=shmulik@metanetworks.com \
--cc=steffen.klassert@secunet.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).