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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: 王擎 <wangqing@vivo.com>
Cc: "efremov@linux.com" <efremov@linux.com>,
	Jiri Slaby <jirislaby@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: 回复: [PATCH] tty: vt: replace snprintf in show functions with sysfs_emit
Date: Fri, 15 Oct 2021 09:29:38 +0200	[thread overview]
Message-ID: <YWkt4qt0pcORpkge@kroah.com> (raw)
In-Reply-To: <SL2PR06MB3082E66577E193F9EE9A09F8BDB99@SL2PR06MB3082.apcprd06.prod.outlook.com>

On Fri, Oct 15, 2021 at 07:10:42AM +0000, 王擎 wrote:
> 
> >> show() must not use snprintf() when formatting the value to be
> >> returned to user space.
> >
> >Again, who is making this "must" requirement?
> >
> >I, as the sysfs maintainer, am not saying that all existing show
> >functions MUST be converted, so I find it hard to believe that someone
> >else is...
> >
> 
> According to Documentation/filesystems/sysfs.txt:
> show() methods of device attributes should return the number
> of bytes printed into the buffer. This is the return value of 
> scnprintf(). snprintf() returns the length the resulting string.
> 
> So, show() must not use snprintf() when formatting 
> the value to be returned to user space. 

Ok, then you need to document this _MUCH_ better, saying that the value
returned by the kernel today is WRONG, and that this is a bugfix.

And can you see the difference here?  Have you tested these?

> Also, use sysfs_emit directly makes more sense.

I agree, but your changelog did not mention that at all.

thanks,

greg k-h

      reply	other threads:[~2021-10-15  7:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-15  6:51 [PATCH] tty: vt: replace snprintf in show functions with sysfs_emit Qing Wang
2021-10-15  6:59 ` Greg Kroah-Hartman
     [not found] ` <APcArgDIEqvUlprBO4*Tk4rA.9.1634281148594.Hmail.wangqing@vivo.com>
2021-10-15  7:10   ` 回复: " 王擎
2021-10-15  7:29     ` Greg Kroah-Hartman [this message]

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