linux-kernel - RE: [RFC PATCH] checkpatch: check for function calls with struct or union on stack

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Message-ID: <9d7441a14897426f8ed5befe8da0cad3@AcuMS.aculab.com>
Date:   Fri, 27 Jul 2018 10:04:54 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Andrew Morton' <akpm@...ux-foundation.org>,
        Joe Perches <joe@...ches.com>,
        Andy Whitcroft <apw@...onical.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: RE: [RFC PATCH] checkpatch: check for function calls with struct or
 union on stack

From: Andrew Morton
> Sent: 26 July 2018 20:28
> On Thu, 26 Jul 2018 12:25:33 -0700 Andrew Morton <akpm@...ux-foundation.org> wrote:
> 
> > I'll give it a spin, see how noisy it is.
> 
> Actually, I would prefer if the message, changelog and title
> used the term "passed by value".  It's a more familiar term
> and it is possible for a passed-by-value aggregate to in fact
> be passed in registers.

You need to detect (and ignore) 'small' structures.
Quite a few ABI pass small structures by value in register(s)
or directly on the stack.

So it can make sense to encapsulate an integer value in a
structure in order to get strong typing.

It would, for instance, make sense to do that for user addresses.

	David

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