linux-kernel - Re: [PATCH v3] iio: st_lsm6dsx: Replace scnprintf with sysfs

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <aIIdU7mJi_cEdRuI@smile.fi.intel.com>
Date: Thu, 24 Jul 2025 14:47:31 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Akshay Bansod <akbansd@...il.com>,
	Lorenzo Bianconi <lorenzo@...nel.org>,
	David Lechner <dlechner@...libre.com>,
	Nuno Sá <nuno.sa@...log.com>,
	Andy Shevchenko <andy@...nel.org>,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] iio: st_lsm6dsx: Replace scnprintf with sysfs_emit

On Wed, Jul 23, 2025 at 04:41:00PM +0100, Jonathan Cameron wrote:
> On Wed, 23 Jul 2025 17:42:28 +0300
> Andy Shevchenko <andriy.shevchenko@...el.com> wrote:
> > On Wed, Jul 23, 2025 at 07:43:59PM +0530, Akshay Bansod wrote:

...

> > >  	fs_table = &hw->settings->fs_table[sensor->id];
> > >  	for (i = 0; i < fs_table->fs_len; i++)
> > > -		len += scnprintf(buf + len, PAGE_SIZE - len, "0.%09u ",
> > > -				 fs_table->fs_avl[i].gain);
> > > -	buf[len - 1] = '\n';
> > > +		len += sysfs_emit_at(buf, len, "0.%09u ",
> > > +				     fs_table->fs_avl[i].gain);
> > > +
> > > +	sysfs_emit_at(buf, len - 1, "\n");  
> > 
> > Still looks a bit weird (while working).
> > 
> > >  	return len;  
> > 
> > I deally we should have a helper doing all this under the hood for plenty of
> > the (existing) users in the kernel.
> 
> hmm I'm not sure generic is terribly easy

I agree, I have some plans for %p specifier extension, but I was stuck with it
and it in half-basked state in some of my local Git branches.

> and I'd prefer this using the
> read_avail callbacks that require the data in an array where ever possible.
> Mind you that does the same print at len - 1 as this.  Let's play. 
> Completely untested.
> 
> 	for (i = 0; i < fs_table->fs_len; i++)
> 		len += sysfs_emit_at(buf, len, "0x%09u%c",
> 				     fs_table->fs_avl[i].gain,
> 				     ((i == fs_table->fs_len - 1) ? '\n', ' '));
> 
> better?

Without extra parentheses this makes the job.


> It's definitely not more readable than the above, but it does avoid the write
> to len - 1.
> 
> > In any case, I leave this change to others to comment, I don't object pushing
> > it in this form, either way len - 1 is simply weird.

-- 
With Best Regards,
Andy Shevchenko