[dpdk-dev] [PATCH] rte_ethdev: fix unsafe memory access by calling RX callback.

[tgw_team(腾讯网关团队)]

So in my patch it was changed to only one memory access.

________________________________
发件人: Stephen Hemminger <stephen at networkplumber.org>
发送时间: 2020年3月5日 1:37
收件人: tgw_team(腾讯网关团队)
抄送: Tencent TGW team; Thomas Monjalon; Ferruh Yigit; Andrew Rybchenko; dev at dpdk.org
主题: Re: [dpdk-dev] [PATCH] rte_ethdev: fix unsafe memory access by calling RX callback.(Internet mail)

On Wed, 4 Mar 2020 16:38:13 +0000
tgw_team(腾讯网关团队) <tgw_team at tencent.com> wrote:

> Sorry, I`ll use a real name in patch v2.
>
> I don't think this is a TOCTOU question.
> The original code works fine when compiled with the -O3 option.
> At this point the compiler will optimize to one memory access.
> But when compiled with -O0, there will be two memory accesses, which is wrong.
> This change was modified with reference to the rte_eth_tx_burst function.

There is nothing C standard that says compiler has to do it either way.
The optimizer may decide to do two memory accesses or one.
Depending on that in anyway is bad practice.