From: Greg KH <gregkh@linuxfoundation.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Tian Tao <tiantao6@hisilicon.com>,
corbet@lwn.net, song.bao.hua@hisilicon.com,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
"Rafael J. Wysocki" <rafael@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [PATCH 1/2] CPU, NUMA topology ABIs: clarify the overflow issue of sysfs pagebuf
Date: Thu, 29 Apr 2021 17:46:24 +0200 [thread overview]
Message-ID: <YIrU0GMcnk6/5mbP@kroah.com> (raw)
In-Reply-To: <146e051b-603c-a6d3-43d8-d083cf2c8119@intel.com>
On Thu, Apr 29, 2021 at 07:21:13AM -0700, Dave Hansen wrote:
> On 4/29/21 12:03 AM, Tian Tao wrote:
> > diff --git a/Documentation/ABI/stable/sysfs-devices-node b/Documentation/ABI/stable/sysfs-devices-node
> > index 484fc04..82dfe64 100644
> > --- a/Documentation/ABI/stable/sysfs-devices-node
> > +++ b/Documentation/ABI/stable/sysfs-devices-node
> > @@ -47,7 +47,10 @@ What: /sys/devices/system/node/nodeX/cpulist
> > Date: October 2002
> > Contact: Linux Memory Management list <linux-mm@kvack.org>
> > Description:
> > - The CPUs associated to the node.
> > + The CPUs associated to the node. The format is like 0-3,
> > + 8-11, 14,17. maximum size is PAGE_SIZE, so the tail
> > + of the string will be trimmed while its size is larger
> > + than PAGE_SIZE.
>
> I think it's pretty arguable that truncating output on a real system is
> an ABI break. Doing this would make the interface rather useless.
>
> Don't we need a real solution rather than throwing up our hands?
>
> Do we think >PAGE_SIZE data out of a sysfs file is a worse ABI break or
> something?
There is a real way to get > PAGE_SIZE out of a sysfs file. The LED
developers had to do this when they ran into this same exact problem.
Make it a binary sysfs file and promise to NEVER create such a file
again in the future :)
thanks,
gre gk-h
next prev parent reply other threads:[~2021-04-29 15:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 7:03 [PATCH 0/2] clarify and cleanup CPU and NUMA topology ABIs Tian Tao
2021-04-29 7:03 ` [PATCH 1/2] CPU, NUMA topology ABIs: clarify the overflow issue of sysfs pagebuf Tian Tao
2021-04-29 14:21 ` Dave Hansen
2021-04-29 15:46 ` Greg KH [this message]
2021-04-29 21:08 ` Song Bao Hua (Barry Song)
2021-04-29 21:38 ` Dave Hansen
2021-04-29 22:32 ` Song Bao Hua (Barry Song)
2021-04-29 22:38 ` Dave Hansen
2021-04-29 22:48 ` Song Bao Hua (Barry Song)
2021-04-30 6:05 ` gregkh
2021-07-23 11:20 ` Song Bao Hua (Barry Song)
2021-07-23 11:28 ` gregkh
2021-07-23 12:48 ` Song Bao Hua (Barry Song)
2021-05-06 23:16 ` kernel test robot
2021-04-29 7:03 ` [PATCH 2/2] Documentation/ABI: Move the topology-related sysfs interface to the right place Tian Tao
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