From: Joe Perches <joe@perches.com>
To: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-kernel@vger.kernel.org, Alex Dewar <alex.dewar90@gmail.com>,
cocci <cocci@systeme.lip6.fr>
Subject: Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs
Date: Fri, 28 Aug 2020 01:22:23 -0700 [thread overview]
Message-ID: <a98b0a411abdaf6b58c73322511087f57353fb22.camel@perches.com> (raw)
In-Reply-To: <526af204ddf95f94012c6132d12693852bfe7442.camel@perches.com>
On Fri, 2020-08-28 at 01:10 -0700, Joe Perches wrote:
> On Fri, 2020-08-28 at 00:58 -0700, Kees Cook wrote:
> > On Thu, Aug 27, 2020 at 09:12:06PM -0700, Joe Perches wrote:
> > > Perhaps something like the below with a sample conversion
> > > that uses single and multiple sysfs_emit uses.
> >
> > On quick review, I like it. :)
> >
> > > [...]
> > > +int sysfs_emit(char *buf, char *pos, const char *fmt, ...)
> > > +{
> > > + int len;
> > > + va_list args;
> > > +
> > > + WARN(pos < buf, "pos < buf\n");
> > > + WARN(pos - buf >= PAGE_SIZE, "pos >= PAGE_SIZE (%tu > %lu)\n",
> > > + pos - buf, PAGE_SIZE);
> > > + if (pos < buf || pos - buf >= PAGE_SIZE)
> > > + return 0;
> >
> > This can be:
> >
> > if (WARN(pos < buf, "pos < buf\n") ||
> > WARN(pos - buf >= PAGE_SIZE, "pos >= PAGE_SIZE (%tu > %lu)\n",
> > pos - buf, PAGE_SIZE))
> > return 0;
>
> I have some vague recollection that WARN could be compiled
> away to nothing somehow. True or false?
>
> If false, sure, of course, it'd be faster too.
I can't find an instance where WARN doesn't return the
condition.
And likely even faster would be to just show "invalid pos"
instead of specific messages.
if (WARN(pos < buf || (pos - buf) >= PAGE_SIZE,
"Invalid pos\n");
return 0;
or maybe use WARN_ONCE or no WARN at all.
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next prev parent reply other threads:[~2020-08-28 8:23 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200824222322.22962-1-alex.dewar90@gmail.com>
[not found] ` <48f2dc90-7852-eaf1-55d7-2c85cf954688@rasmusvillemoes.dk>
[not found] ` <20200827071537.GA168593@kroah.com>
[not found] ` <20200827131819.7rcl2f5js3hkoqj2@lenovo-laptop>
[not found] ` <def24e9e-018c-9712-0d07-d4cbc84f07d9@rasmusvillemoes.dk>
[not found] ` <20200827144846.yauuttjaqtxaldxg@lenovo-laptop>
2020-08-27 16:58 ` [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs Joe Perches
2020-08-27 19:42 ` Julia Lawall
2020-08-27 20:29 ` Joe Perches
2020-08-27 21:00 ` Joe Perches
2020-08-27 21:29 ` Julia Lawall
2020-08-27 22:03 ` David Laight
2020-08-27 22:11 ` Joe Perches
2020-08-27 22:16 ` Kees Cook
2020-08-27 21:01 ` Denis Efremov
2020-08-27 21:36 ` Julia Lawall
2020-08-27 21:44 ` Joe Perches
2020-08-27 22:38 ` Denis Efremov
2020-08-27 22:48 ` Joe Perches
2020-08-27 22:20 ` Kees Cook
2020-08-27 22:45 ` Joe Perches
2020-08-28 4:12 ` Joe Perches
2020-08-28 7:58 ` Kees Cook
2020-08-28 8:10 ` Joe Perches
2020-08-28 8:22 ` Joe Perches [this message]
2020-08-28 7:39 ` David Laight
2020-08-27 21:54 ` David Laight
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