linux-kernel - Re: [RFC][PATCH] rcu: Use typeof(p) instead of typeof(*p) *

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: <ed3b6265-b073-bab2-4a05-d7a8acf7763d@rasmusvillemoes.dk>
Date:   Tue, 5 Oct 2021 20:48:42 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     rostedt <rostedt@...dmis.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Paul <paulmck@...ux.vnet.ibm.com>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        "Joel Fernandes, Google" <joel@...lfernandes.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, rcu <rcu@...r.kernel.org>,
        netfilter-devel <netfilter-devel@...r.kernel.org>,
        coreteam <coreteam@...filter.org>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [RFC][PATCH] rcu: Use typeof(p) instead of typeof(*p) *

On 05/10/2021 20.06, Mathieu Desnoyers wrote:
> ----- On Oct 5, 2021, at 2:01 PM, Rasmus Villemoes linux@...musvillemoes.dk wrote:
> 
>> I would think that one could avoid that churn by saying
>>
>>  typeof((p) + 0)
>>
>> instead of just "typeof(p)", to force the decay to a pointer.
> 
> Also, AFAIU, the compiler wants to know the sizeof(p) in order to evaluate
> (p + 0). Steven's goal is to hide the structure declaration, so that would
> not work either.

Gah, you're right. I was hoping the frontend would see that +0 could be
optimized away and only affect the type of the expression, but it does
give 'error: invalid use of undefined type ‘struct abc’'. Sorry for the
noise.

Rasmus