From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
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Subject: Re: [PATCH v2 5/9] mm: Initialize struct vm_unmapped_area_info
Date: Tue, 27 Feb 2024 15:00:46 +0000 [thread overview]
Message-ID: <ad24469275325b86ed316df36153fcdb2863454f.camel@intel.com> (raw)
In-Reply-To: <94a2b919-e03b-4ade-b13e-7774849dc02b@csgroup.eu>
On Tue, 2024-02-27 at 07:02 +0000, Christophe Leroy wrote:
> > It could be possible to initialize the new field for each arch to
> > 0, but
> > instead simply inialize the field with a C99 struct inializing
> > syntax.
>
> Why doing a full init of the struct when all fields are re-written a
> few
> lines after ?
>
> If I take the exemple of powerpc function slice_find_area_bottomup():
>
> struct vm_unmapped_area_info info;
>
> info.flags = 0;
> info.length = len;
> info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
> info.align_offset = 0;
>
> For me it looks better to just add:
>
> info.new_field = 0; /* or whatever value it needs to have */
Hi,
Thanks for taking a look. Yes, I guess that should have some
justification. I was thinking of two reasons:
1. No future additions of optional parameters would need to make tree
wide changes like this.
2. The change is easier to review and get correct because the necessary
context is within a single line. For example, in that function some of
members are set within a while loop. The place you pointed seems to be
the correct one, but a diff that had the new field set after:
info.high_limit = addr;
...would look correct too, but not be.
What is the concern with C99 initialization? FWIW, the full series also
removes an indirect branch, and probably is a net win for performance
in this path.
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next prev parent reply other threads:[~2024-02-27 15:00 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240226190951.3240433-1-rick.p.edgecombe@intel.com>
2024-02-26 19:09 ` [PATCH v2 5/9] mm: Initialize struct vm_unmapped_area_info Rick Edgecombe
2024-02-27 7:02 ` Christophe Leroy
2024-02-27 15:00 ` Edgecombe, Rick P [this message]
2024-02-27 18:07 ` Kees Cook
2024-02-27 18:16 ` Christophe Leroy
2024-02-27 20:25 ` Edgecombe, Rick P
2024-02-28 13:22 ` Christophe Leroy
2024-02-28 17:01 ` Edgecombe, Rick P
2024-02-28 23:10 ` Christophe Leroy
2024-02-28 17:21 ` Kees Cook
2024-03-02 0:47 ` Edgecombe, Rick P
2024-03-02 1:51 ` Kees Cook
2024-03-04 18:00 ` Christophe Leroy
2024-03-04 18:03 ` Edgecombe, Rick P
2024-02-28 11:51 ` Kirill A. Shutemov
2024-03-02 0:17 ` [RFC v2.1 01/12] ARC: Use initializer for " Rick Edgecombe
2024-03-02 4:42 ` Vineet Gupta
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