linux-kernel - Re: [PATCH] bitmap: remove explicit newline handling using scnprintf format string

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Date:	Mon, 27 Apr 2015 17:39:13 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Tejun Heo <tj@...nel.org>
CC:	Sudeep Holla <sudeep.holla@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Pawel Moll <Pawel.Moll@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: Re: [PATCH] bitmap: remove explicit newline handling using scnprintf
 format string

Hi Tejun,

On 27/04/15 17:30, Tejun Heo wrote:
> Hello, Sudeep.
>
> On Mon, Apr 27, 2015 at 05:26:16PM +0100, Sudeep Holla wrote:
>> Completely agree and in-fact we did discuss that internally too.
>> But since this function deals only with page size buffers, we thought
>> it's highly unlikely to hit that corner case.
>
> Ah, yeah, right.  It'd probably be worthwhile to document the above in
> the description tho.
>

OK will update the commit log and the doxygen description.

>>> Given that bitmap outputs can be pretty long, this behavior
>>> difference has a minute but still non-zero chance of causing something
>>> surprising.  There are multiple copies of the above function in arch
>>> codes too.
>>
>> I assumed that I had consolidated most of them in commit 5aaba36318e5
>> ("cpumask: factor out show_cpumap into separate helper function").
>> I might have missed, will have a look at it again.
>
> I noticed them while %pb[l] conversion but was too lazy to actually do
> anything.  Thanks a lot for actually taking care of them.
>

No worries.

>>> We prolly want to audit the usages to verify that the
>>> passed in buffer is always big enough at which point the above
>>> function and its copies can simply be replaced with direct scnprintf()
>>> calls.  This function doesn't actually add anything.
>>
>> Ah, right that would be much simpler.
>
> Yeah, let's get rid of it.
>

/me confused, is it fine to push this patch first, and follow up later
after auditing thoroughly to replace with direct scnprintf()

Regards,
Sudeep
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