From: Dave Hansen <dave.hansen@intel.com>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>,
"tiantao (H)" <tiantao6@hisilicon.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@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 14:38:36 -0700 [thread overview]
Message-ID: <7c663f7e-07e0-6d95-3012-6e31a1b78f7e@intel.com> (raw)
In-Reply-To: <602918a1e2214ea7bd0890a751975566@hisilicon.com>
On 4/29/21 2:08 PM, Song Bao Hua (Barry Song) wrote:
>> Do we think >PAGE_SIZE data out of a sysfs file is a worse ABI break or
>> something?
> This kind of cpu list ABIs have been there for many years but have
> never been documented well.
>
> We have two ABIs:
> xxx_cpus - in format like 3333333333
> xxx_cpus_list - in format like 0,3,5,7,9,11,13....
>
> xxx_cpus_list is another human-readable version of xxx_cpus. It doesn't
> include any more useful information than xxx_cpus.
>
> xxx_cpus won't overflow based on BUILD_BUG_ON and maximum NR_CPUS
> in kconfig nowadays.
>
> if people all agree the trimmed list is a break of ABI, I think we may
> totally remove this list. For these days, this list probably has never
> overflowed but literally this could happen.
>
> thoughts?
From what Greg said, it sounds like removing the BUILD_BUG_ON(), making
it a binary sysfs file, and making it support arbitrary lengths is the
way to go.
next prev parent reply other threads:[~2021-04-29 21:38 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
2021-04-29 21:08 ` Song Bao Hua (Barry Song)
2021-04-29 21:38 ` Dave Hansen [this message]
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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