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From: Joe Perches <joe@perches.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: David Laight <David.Laight@ACULAB.COM>,
	'Andrew Morton' <akpm@linux-foundation.org>,
	Andy Whitcroft <apw@canonical.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] checkpatch: check for function calls with struct or union on stack
Date: Sat, 28 Jul 2018 10:20:44 -0700	[thread overview]
Message-ID: <b8d9aa953d1e760b35bd4ef6c689dfb777c8a6a0.camel@perches.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1807280823200.2466@hadrien>

(unintentionally sent partial reply, better now)

On Sat, 2018-07-28 at 08:25 +0200, Julia Lawall wrote:
> On Fri, 27 Jul 2018, Joe Perches wrote:
[]
> > It might make sense for this sort of check to be
> > added to coccinelle or maybe as a compiler warning
> > when the struct is larger than some size.
> > 
> > Original thread for Julia:
> > https://lore.kernel.org/patchwork/patch/967890/
> 
> Coccinelle doesn't directly know the size of the structure, but it can
> count the number of fields.  Maybe a case with an update in the function
> body

Perhaps this might be the most useful to check.

>  or at least 3 fields is worth reporting on?

Maybe, maybe not.  For instance:

lib/vsprintf.c uses struct printf_spec which is
5 fields totaling 8 bytes and that fits nicely in
a single register on x86-64 so there are good
reasons why structs could be passed by value.

Maybe structs with arrays or other structs would
make more sense.



      parent reply	other threads:[~2018-07-28 17:20 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-26 18:27 [RFC PATCH] checkpatch: check for function calls with struct or union on stack Joe Perches
2018-07-26 19:25 ` Andrew Morton
2018-07-26 19:28   ` Andrew Morton
2018-07-26 20:05     ` Joe Perches
2018-07-26 20:38       ` Andrew Morton
2018-07-27 10:04     ` David Laight
2018-07-27 10:08       ` Joe Perches
2018-07-27 10:21         ` David Laight
2018-07-27 10:36           ` Joe Perches
2018-07-28  6:25             ` Julia Lawall
2018-07-28 17:14               ` Joe Perches
2018-07-28 17:24                 ` Julia Lawall
2018-07-28 17:20               ` Joe Perches [this message]

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