Re: script to find incorrect tests on unsigneds

[Matthew Wilcox <matthew@wil.cx>]

On Fri, Apr 18, 2008 at 09:08:55PM +0200, Julia Lawall wrote:
> I found 63 occurrences of this problem with the following semantic match
> (http://www.emn.fr/x-info/coccinelle/):
> 
> @@ unsigned int i; @@
> 
> * i < 0

Could you also look for unsigned long?

> I looked through all of the results by hand, and they all seem to be 
> problems.  In many cases, it seems like the variable should not be 
> unsigned as it is used to hold the return value of a function that might 
> return a negative error code, but I haven't looked into this in detail.

The problem will be if the variable is supposed to be unsigned in some
uses and signed in others.  The IS_ERR_VALUE() macro from linux/err.h
may be useful for this.

> In the output below, the lines that begin with a single start contain a 
> test of whether an unsigned variable or structure field is less than 0.
> The output is actually generated with diff, but I converted the -s to *s 
> to avoid confusion.

I'll respond to some of these, cc'ing the appropriate people.  Thanks
for doing this.

-- 
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