linux-kernel - Re: [PATCH v2 1/2] lib/strtox: introduce kstrtoull

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Date: Wed, 27 Dec 2023 16:38:32 +1100
From: David Disseldorp <ddiss@...ba.org>
To: Qu Wenruo <quwenruo.btrfs@....com>
Cc: Qu Wenruo <wqu@...e.com>, linux-btrfs@...r.kernel.org, Andrew Morton
 <akpm@...ux-foundation.org>, Christophe JAILLET
 <christophe.jaillet@...adoo.fr>, Andy Shevchenko
 <andriy.shevchenko@...ux.intel.com>, David Laight
 <David.Laight@...LAB.COM>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] lib/strtox: introduce kstrtoull_suffix() helper

On Sat, 23 Dec 2023 20:27:30 +1030, Qu Wenruo wrote:

> On 2023/12/20 16:08, David Disseldorp wrote:
...
> >> +#define KSTRTOULL_SUFFIX_DEFAULT (SUFFIX_K | SUFFIX_M | SUFFIX_G | SUFFIX_T | SUFFIX_P)  
> >
> > I think it'd be clearer if you dropped this default and had callers
> > explicitly provide the desired suffix mask.  
> 
> Well, that would be long, and would be even longer as the newer naming
> would be MEMPARSE_SUFFIX_*, to be more explicit on what the suffix is for...
> 
> And I really want callers to choose a saner default suffix, thus here
> comes the default one.
> 
> In fact, in my next version, I also found that there are some memparse()
> call sites benefits from the newer suffixes (although won't for the "E"
> one).
> The example is the call site setup_elfcorehdr(). Where the comment only
> mentions KMG, but since memparse() silently added "PE" suffixes, maybe
> on some mainframes we saved some time for one or two lucky admins.

I think it's a sane default, my concern is that _DEFAULT says nothing
about supported units from the caller's perspective. Perhaps
MEMPARSE_SUFFIX_KMGTP or MEMPARSE_UNITS_KMGTP would be clearer.

...
> > With the above changes made, feel free to add
> > Reviewed-by: David Disseldorp <ddiss@...e.de>  
> 
> Thanks for the review, but I'm afraid the newer version would be another
> beast.
> 
> All the ommitted comments would be addressed a in new series.
> >
> > I'll leave the review of patch 2/2 up to others, as I'm still a little
> > worried about sysfs trailing whitespace regressions.  
> 
> That won't be a problem anymore, the new series would keep the old
> @retptr behavior, thus for btrfs part it won't be changed at all.

Sounds good. Will follow up there.

Cheers, David