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    SubjectRe: [PATCH] video/saa7164: Fix sparse warning: Using plain integer as NULL pointer
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    On Tue, Jan 25, 2011 at 5:54 PM, Peter Hüwe <PeterHuewe@gmx.de> wrote:
    > Hi Julia,
    >
    > thanks for your input.
    > So do I understand you correctly if I say
    > if(!x) is better than if(x==NULL) in any case?
    >
    > Or only for the kmalloc family?
    >
    > Do you remember the reason why !x should be preferred?
    >
    > In Documentation/CodingStyle ,  Chapter 7: Centralized exiting of functions
    > there is a function fun with looks like this:
    > int fun(int a)
    > {
    >    int result = 0;
    >    char *buffer = kmalloc(SIZE);
    >
    >    if (buffer == NULL)
    >        return -ENOMEM;
    >
    >    if (condition1) {
    >        while (loop1) {
    >            ...
    >        }
    >        result = 1;
    >        goto out;
    >    }
    >    ...
    > out:
    >    kfree(buffer);
    >    return result;
    > }
    >
    >
    > -->  So   if (buffer == NULL) is in the official CodingStyle - maybe we should
    > add a paragraph there as well ;)
    >
    >
    > Don't get me wrong, I just want to learn ;)

    To my knowledge, the current CodingStyle doesn't enforce a particular
    standard in this regard, leaving it at the discretion of the author.

    Whether to do (!foo) or (foo == NULL) is one of those debates people
    have similar to whether to use tabs as whitespace. People have
    differing opinions and there is no clearly "right" answer. Personally
    I strongly prefer (foo == NULL) as it makes it blindingly obvious that
    it's a pointer comparison, whereas (!foo) leaves you wondering whether
    it's an integer or pointer comparison.

    All that said, you shouldn't submit patches which arbitrarily change
    from one format to the other. With regards to the proposed patch, you
    should follow whatever style the author employed in the rest of the
    file.

    Cheers,

    Devin

    --
    Devin J. Heitmueller - Kernel Labs
    http://www.kernellabs.com
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