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SubjectRe: [PATCH] fs/eventpoll: error handling micro-cleanup
Davide Libenzi wrote:
> On Sun, 1 Oct 2006, Jeff Garzik wrote:
>
>> Davide Libenzi wrote:
>>> On Sun, 1 Oct 2006, Jeff Garzik wrote:
>>>
>>>> While reviewing the 'may be used uninitialized' bogus gcc warnings,
>>>> I noticed that an error code assignment was only needed if an error had
>>>> actually occured.
>>> But that saved one line of code, and there are countless occurences in the
>>> kernel of such code pattern ;)
>> I'm not sure there are countless occurrences with PTR_ERR(). The line is
>> incorrect (but harmless) if inode is a valid pointer...
>
> I just tried a `find /usr/src/linux-2.6.16/ -type f -exec grep -H -C 2 PTR_ERR {} \;`
> and looked at the cases where the error variable is assigned in any case
> before the test. Same code pattern as, like:
>
> error = -EFAULT;
> if (copy_from_user(...))
> goto kaboom;

No, that's quite different. I'm talking about

ptr = get_a_pointer_from_somewhere()
error = PTR_ERR(ptr)

See the difference? The error variable is directly assigned from a
potentially-valid pointer. Doing that is quite error prone, whereas
error = -EFOO
is not.

Jeff


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