linux-kernel - Re: [RFC] seq_buf: Export symbols to external modules

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Message-ID: <87eeru8znu.fsf@linux.ibm.com>
Date:   Fri, 08 May 2020 16:24:45 +0530
From:   Vaibhav Jain <vaibhav@...ux.ibm.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Michael Ellerman <ellerman@....ibm.com>,
        Piotr Maziarz <piotrx.maziarz@...ux.intel.com>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [RFC] seq_buf: Export symbols to external modules


Steven Rostedt <rostedt@...dmis.org> writes:

> On Fri, 17 Apr 2020 14:47:48 +0530
> Vaibhav Jain <vaibhav@...ux.ibm.com> wrote:
>
>> Having these symbols exported to modules should simplify generating file
>> content for pseudo file systems like sysfs or procfs. Many of the in
>> kernel modules export atleast one such attribute file. Using seq_buf
>> api provides a safe way to populate the read buffers for these attrs
>> as these string buffers are PAGE_SIZE in length and a buggy module can
>> easily cause an overflow.
>> 
>> My specific use-case is exporting a set of nvdimm specific flags from
>> papr_scm kernel module [1] via sysfs through a patch proposed at [2] and
>> using seq_buf should considerably simply my code as suggested by Mpe
>> at [3].
>> 
>> [1] arch/powerpc/platforms/pseries/papr_scm.c
>> [2] https://lore.kernel.org/linux-nvdimm/20200331143229.306718-2-vaibhav@linux.ibm.com
>> [3] https://lore.kernel.org/linux-nvdimm/878sjetcis.fsf@mpe.ellerman.id.au
>
> This patch should be added to a patch series that needs it. Then I'll give
> my ack to it. That way, there's a reason to export them.
Thanks Steve,

I have posted a patch series at 
https://lore.kernel.org/linux-nvdimm/20200508104922.72565-1-vaibhav@linux.ibm.com/
titled "powerpc/papr_scm: Add support for reporting nvdimm health" that
contains a patch to export seq_buf_printf() viz patch
https://lore.kernel.org/linux-nvdimm/20200508104922.72565-3-vaibhav@linux.ibm.com/
titled "seq_buf: Export seq_buf_printf() to external modules"

~ Vaibhav
>
> -- Steve