netdev - Re: [PATCH net-next v12 06/13] page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c9333388-6906-4df9-92b4-ecfd324f5891@gmail.com>
Date: Mon, 24 Jun 2024 01:12:46 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-alpha@...r.kernel.org,
 linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
 sparclinux@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
 bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Donald Hunter <donald.hunter@...il.com>, Jonathan Corbet <corbet@....net>,
 Richard Henderson <richard.henderson@...aro.org>,
 Ivan Kokshaysky <ink@...assic.park.msu.ru>, Matt Turner
 <mattst88@...il.com>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
 Helge Deller <deller@....de>, Andreas Larsson <andreas@...sler.com>,
 Sergey Shtylyov <s.shtylyov@....ru>, Jesper Dangaard Brouer
 <hawk@...nel.org>, Ilias Apalodimas <ilias.apalodimas@...aro.org>,
 Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Arnd Bergmann <arnd@...db.de>, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
 Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, Steffen Klassert
 <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>,
 David Ahern <dsahern@...nel.org>,
 Willem de Bruijn <willemdebruijn.kernel@...il.com>,
 Shuah Khan <shuah@...nel.org>, Sumit Semwal <sumit.semwal@...aro.org>,
 Christian König <christian.koenig@....com>,
 Bagas Sanjaya <bagasdotme@...il.com>, Christoph Hellwig <hch@...radead.org>,
 Nikolay Aleksandrov <razor@...ckwall.org>, David Wei <dw@...idwei.uk>,
 Jason Gunthorpe <jgg@...pe.ca>, Yunsheng Lin <linyunsheng@...wei.com>,
 Shailend Chand <shailend@...gle.com>,
 Harshitha Ramamurthy <hramamurthy@...gle.com>,
 Shakeel Butt <shakeel.butt@...ux.dev>, Jeroen de Borst
 <jeroendb@...gle.com>, Praveen Kaligineedi <pkaligineedi@...gle.com>,
 linux-mm@...ck.org, Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH net-next v12 06/13] page_pool: devmem support

On 6/21/24 19:48, Mina Almasry wrote:
> On Mon, Jun 17, 2024 at 7:17 AM Pavel Begunkov <asml.silence@...il.com> wrote:
...
>>>    static inline unsigned long netmem_to_pfn(netmem_ref netmem)
>>>    {
>>> +     if (netmem_is_net_iov(netmem))
>>> +             return 0;
>>
>> IIRC 0 is a valid pfn. Not much of a concern since it's
>> used only for tracing, but might make sense to pass some
>> invalid pfn if there is one
>>
> 
> AFAIU all non-negative pfns are technically valid pfns if the machine
> is big enough.
> 
> I could have this function return long long instead of unsigned long
> so I can return a negative number for errors, and then cast to
> unsigned long when I figure out it's actually a pfn. Seemed like such
> a hassle especially since the call site is just tracing that I figured
> it's not that worth it.

Yeah, sounds like an overkill for tracing

> 
>>> +
>>>        return page_to_pfn(netmem_to_page(netmem));
>>>    }
>>>
>> ...
>>>    static inline netmem_ref netmem_compound_head(netmem_ref netmem)
>>>    {
>>> +     /* niov are never compounded */
>>> +     if (netmem_is_net_iov(netmem))
>>> +             return netmem;
>>> +
>>>        return page_to_netmem(compound_head(netmem_to_page(netmem)));
>>>    }
>>>
>>> +static inline void *netmem_address(netmem_ref netmem)
>>
>> I don't think it's used anywhere, do I miss it?
>>
> 
> Ah, It's used by the GVE devmem implementation:
> https://github.com/mina/linux/commit/da89baa81873d457cbf7b49ee6b4f0d66855b205
> 
> I could leave it out of this patch, then add it with the follow up GVE
> devmem implementation, but I figured almost for sure drivers are going
> to need this eventually, and it's small, so just put it here.

Either way is fine by me, checking the function is not leftovers

-- 
Pavel Begunkov