linux-kernel - Re: [PATCH 02/17] mm: mmu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Fri, 01 Apr 2011 17:07:20 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	torvalds@...ux-foundation.org
Cc:	a.p.zijlstra@...llo.nl, avi@...hat.com, mel@....ul.ie,
	aarcange@...hat.com, tglx@...utronix.de, riel@...hat.com,
	mingo@...e.hu, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
	linux-mm@...ck.org, benh@...nel.crashing.org,
	hugh.dickins@...cali.co.uk, npiggin@...nel.dk,
	paulmck@...ux.vnet.ibm.com, yanmin_zhang@...ux.intel.com,
	schwidefsky@...ibm.com, rmk@....linux.org.uk, lethal@...ux-sh.org,
	jdike@...toit.com, tony.luck@...el.com, hughd@...gle.com
Subject: Re: [PATCH 02/17] mm: mmu_gather rework

From: Linus Torvalds <torvalds@...ux-foundation.org>
Date: Fri, 1 Apr 2011 09:13:51 -0700

> What's the difference? Integer assignment makes a hell of a difference. Do this:
> 
>   long long expression = ...
>   ...
>   bool val = expression;
> 
> and depending on implementation it will either just truncate the value
> to a random number of bits, or actually do a compare with zero.

But note that, as you indicate, using int's to store boolean values
have this exact problem.

And most of the time people are converting an "int used as a boolean
value" into a "bool".

At least the "bool" has a chance of giving true boolean semantics in
the case you describe, whereas the 'int' always has the potential
truncation issue.

So, personally, I see it as a net positive to convert int to bool when
the variable is being used to take on true/false values.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/