Messages in this thread | | | Date | Thu, 7 Dec 2006 16:36:31 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH 2.6.19] drivers/media/video/cpia2/cpia2_usb.c: Free previously allocated memory (in array elements) if kmalloc() returns NULL. |
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On Fri, 8 Dec 2006, Mariusz Kozlowski wrote:
> > > Just for future. Shorter and more readable version of your for(...) thing: > > > > > > while (i--) { > > > ... > > > } > > > > > > > No, that is not equivalent. > > > > You want > > while (i-- >= 0) { > > ... > > } > > > > Not really. That will stop at -1 not 0. >
It depends on your intent. Generally speaking,
while (i--) { ... }
is never what you want. Adding the check for being greater than 0 stops potential bugs from signed int i being negative. The only drawback on x86 is that it sets a byte based on the greater condition with setg and tests it later with testb for every iteration. This use of testb will _always_ use the same addressable byte registers for both its operands.
Based on this particular patch, I agree that
while (i-- > 0) { ... }
will do the job. This is equivalent to the original for loop and ensures that a negative value of i is never iterated on (even though it admittedly would never be negative in this instance to begin with).
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