linux-kernel - Re: [PATCH v2 01/24] input: Add ff-memless-next module

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1398272768.23603.1.camel@linux-fkkt.site>
Date:	Wed, 23 Apr 2014 19:06:08 +0200
From:	Oliver Neukum <oneukum@...e.de>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Michal Malý <madcatxster@...oid-pointer.net>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	jkosina@...e.cz, elias.vds@...il.com, anssi.hannula@....fi,
	simon@...gewell.org
Subject: Re: [PATCH v2 01/24] input: Add ff-memless-next module

On Wed, 2014-04-23 at 08:59 -0700, Dmitry Torokhov wrote:
> On Wed, Apr 23, 2014 at 02:12:59PM +0200, Oliver Neukum wrote:
> > On Tue, 2014-04-22 at 15:59 +0200, Michal Malý wrote:
> > > +/* Some devices might have a limit on how many uncombinable effects
> > > + * can be played at once */
> > > +static int mlnx_upload_conditional(struct mlnx_device *mlnxdev,
> > > +                                  const struct ff_effect *effect)
> > > +{
> > > +       struct mlnx_effect_command ecmd = {
> > > +               .cmd = MLNX_UPLOAD_UNCOMB,
> > > +               .u.uncomb.id = effect->id,
> > > +               .u.uncomb.effect = effect
> > > +       };
> > > +       return mlnxdev->control_effect(mlnxdev->dev, mlnxdev->private,
> > > &ecmd);
> > > +}
> > > +
> > 
> > This mean you are building the structure on the stack
> > 
> > 1. Are you sure nobody retains a reference?
> > 2. That is needlessly inefficient
> 
> Why is it inefficient?

The compiler has to include the data structure and then make
a memcopy to the stack. Instead a pointer to the predined structure
could be passed.

	Regards
		Oliver


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/