Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 30 May 2003 16:24:34 +0200 | From | Andries Brouwer <> | Subject | Re: buffer_head.b_bsize type |
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On Thu, May 29, 2003 at 04:28:41AM -0700, William Lee Irwin III wrote:
> The thought behind my comment was that it didn't make sense to allow > the representation to go negative. There of course shouldn't ever be > any need to allow >= 2GB b_size to be representable.
Not about this particular case, but as a general remark: Use of unsigned is dangerous - use of int is far preferable, everywhere that is possible.
With ints the test a+b > c is equivalent to the test a > c-b. Intuition works.
As soon as there is some unsigned in an expression comparisons get counterintuitive because -1 is very large. Thus, 1+sizeof(int) > 3 is true, but 1 > 3-sizeof(int) is false.
It has happened several times that kernel code was broken because some variable (that always was nonnegative) was made unsigned.
Andries
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