linux-kernel - Re: A CodingStyle suggestion

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Date:	Sat, 03 Feb 2007 16:21:18 -0800
From:	Roland Dreier <rdreier@...co.com>
To:	"Ahmed S. Darwish" <darwish.07@...il.com>
Cc:	Richard Knutsson <ricknu-0@...dent.ltu.se>,
	linux-kernel@...r.kernel.org, randy.dunlap@...cle.com
Subject: Re: A CodingStyle suggestion

 > Good catch :). A small grep of `access_ok' reveals that it's always used in the 
 > form of:
 > if (!access_ok()) { .. }
 > 
 > I can conclude that verbal/imperative methods like `kmalloc, add_work' be 
 > checked as:
 > ret = do_work();
 > if (ret) { ... }
 > and predicate methods like `acess_ok, pci_dev_present' be checked like:
 > if (!access_ok) { ... }
 > if (pci_dev_present) { ...}
 > 
 > Any comments ?

I don't think that's really the distinction that matters.  I think
really the issue is that assignment within an if is hard to read, so

	ret = foo(a, b);
        if (ret) { ... }

is clearly preferred to

	if ((ret = foo(a,b))) { ... }

However, in my opinion something like

	if (foo(a,b)) { ... }

if perfectly fine if the return value of foo is not needed anywhere
else.  In other words, there's no sense introducing a temporary
variable to hold the return value if you're never going to do anything
with it other than check it on the next line.

 - R.
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