From: Jeremy Fitzhardinge <jeremy@goop.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: xen-devel@lists.xensource.com,
Jeremy Fitzhardinge <jeremy@xensource.com>,
matt mooney <mfm@muteddisk.com>,
x86@kernel.org, kernel-janitors@vger.kernel.org,
Chris Wright <chrisw@sous-sol.org>,
virtualization@lists.osdl.org, Ingo Molnar <mingo@redhat.com>,
Tejun Heo <tj@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [PATCH 1/4] x86: remove cast from void*
Date: Tue, 14 Sep 2010 11:46:47 -0700 [thread overview]
Message-ID: <4C8FC317.8080408@goop.org> (raw)
In-Reply-To: <4C8FBD01.40900@zytor.com>
On 09/14/2010 11:20 AM, H. Peter Anvin wrote:
> On 09/14/2010 10:49 AM, Jeremy Fitzhardinge wrote:
>> On 09/13/2010 10:18 PM, matt mooney wrote:
>>> Unnecessary cast from void* in assignment.
>> Not very keen on this. The cast may not be strictly required, but it
>> does document what's going on there.
>>
> But unnecessary casts are problematic in that if the type changes, they
> can hide a real bug in the future.
If page->private changes in a way which invalidates this kind of usage,
I would hope it would also change name to something more descriptive of
its new role. If it changes type but is broadly compatible with this
usage (say, void * -> unsigned long), then the cast won't matter, or
will become a requirement.
I'm more concerned about "user_ptr" changing type, in which case the
cast will highlight the problem.
In general, the casts from these kinds of generic/polymorphic fields let
you easily eyeball how they're being used, without having to work out
what the type of the other side is.
J
next prev parent reply other threads:[~2010-09-14 18:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 5:18 [PATCH 1/4] x86: remove cast from void* matt mooney
2010-09-14 17:49 ` Jeremy Fitzhardinge
2010-09-14 18:20 ` H. Peter Anvin
2010-09-14 18:46 ` Jeremy Fitzhardinge [this message]
2010-09-21 18:39 ` Jeremy Fitzhardinge
2010-09-21 19:15 ` matt mooney
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