From: Jan Engelhardt <jengelh@inai.de>
To: rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
rostedt <rostedt@goodmis.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Paul <paulmck@linux.vnet.ibm.com>,
Josh Triplett <josh@joshtriplett.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
"Joel Fernandes, Google" <joel@joelfernandes.org>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Florian Westphal <fw@strlen.de>,
"David S. Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Jakub Kicinski <kuba@kernel.org>, rcu <rcu@vger.kernel.org>,
netfilter-devel <netfilter-devel@vger.kernel.org>,
coreteam <coreteam@netfilter.org>,
netdev <netdev@vger.kernel.org>
Subject: Re: [RFC][PATCH] rcu: Use typeof(p) instead of typeof(*p) *
Date: Tue, 5 Oct 2021 20:28:54 +0200 (CEST) [thread overview]
Message-ID: <826o327o-3r46-3oop-r430-8qr0ssp537o3@vanv.qr> (raw)
In-Reply-To: <639278914.2878.1633457192964.JavaMail.zimbra@efficios.com>
On Tuesday 2021-10-05 20:06, Mathieu Desnoyers wrote:
>> instead of just "typeof(p)", to force the decay to a pointer.
>
>If the type of @p is an integer, (p) + 0 is still valid, so it will not
>prevent users from passing an integer type as argument, which is what
>the current implementation prevents.
>
>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.
>>>> typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p);
#define static_cast(type, expr) ((struct { type x; }){(expr)}.x)
typeof(p) p1 = (typeof(p) __force)static_cast(void *, READ_ONCE(p));
Let the name not fool you; it's absolutely _not_ the same as C++'s
static_cast, but still: it does emit a warning when you do pass an
integer, which is better than no warning at all in that case.
*flies away*
next prev parent reply other threads:[~2021-10-05 18:29 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 13:47 [RFC][PATCH] rcu: Use typeof(p) instead of typeof(*p) * Steven Rostedt
2021-10-05 15:15 ` Mathieu Desnoyers
2021-10-05 15:58 ` Steven Rostedt
2021-10-05 16:15 ` Mathieu Desnoyers
2021-10-05 16:29 ` Paul E. McKenney
2021-10-05 16:40 ` Steven Rostedt
2021-10-11 8:39 ` David Laight
2021-10-12 14:18 ` Mathieu Desnoyers
2021-10-12 15:36 ` Steven Rostedt
2021-10-05 16:18 ` Linus Torvalds
2021-10-05 16:37 ` Steven Rostedt
2021-10-05 16:47 ` Linus Torvalds
2021-10-05 16:42 ` Steven Rostedt
2021-10-05 18:01 ` Rasmus Villemoes
2021-10-05 18:06 ` Mathieu Desnoyers
2021-10-05 18:28 ` Jan Engelhardt [this message]
2021-10-05 18:40 ` Steven Rostedt
2021-10-05 19:06 ` Jan Engelhardt
2021-10-05 19:40 ` Steven Rostedt
2021-10-05 19:46 ` Linus Torvalds
2021-10-05 20:02 ` Steven Rostedt
2021-10-05 19:49 ` Mathieu Desnoyers
2021-10-05 20:06 ` Steven Rostedt
2021-10-05 20:37 ` Steven Rostedt
2021-10-05 20:45 ` Linus Torvalds
2021-10-05 21:05 ` Steven Rostedt
2021-10-05 21:09 ` Jan Engelhardt
2021-10-05 21:24 ` Steven Rostedt
2021-10-11 8:34 ` David Laight
2021-10-05 21:27 ` Linus Torvalds
2021-10-05 22:26 ` Jan Engelhardt
2021-10-05 18:48 ` Rasmus Villemoes
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