On 31 October 2017 at 09:45, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> On Mon, Oct 30, 2017 at 02:03:13PM +0100, Ulf Hansson wrote:
>> On 30 October 2017 at 13:15, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>> > On Mon, Oct 30, 2017 at 12:40:39PM +0100, Ulf Hansson wrote:
>> >> On 27 October 2017 at 21:31, SF Markus Elfring
>> >> <elfring@xxxxxxxxxxxxxxxxxxxxx> wrote:
>> >> > From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
>> >> > Date: Fri, 27 Oct 2017 21:21:40 +0200
>> >> >
>> >> > Add a jump target so that a specific string copy operation is stored
>> >> > only once at the end of this function implementation.
>> >> > Replace two calls of the function "strncpy" by goto statements.
>> >> >
>> >> > This issue was detected by using the Coccinelle software.
>> >> >
>> >> > Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
>> >>
>> >> Thanks, applied for next!
>> >>
>> >
>> > What's the advantage of this patch? The new code seems more complicated
>> > to me and GCC automatically reuses duplicate constant strings so there
>> > is no memory savings.
>>
>> It looked to me that the error path got a bit cleaner. However, I
>> guess it's matter of taste.
>>
>> If you insist, I can drop it.
>
> I'm on the kernel-janitors list so I am CC'd on all of Markus's patches.
> It's not my code and I'm tired of being the anti-Markus guy so this
> patch is fine. Markus has a tool that finds duplicate strings and he
> uses gotos to avoid them. I don't think duplicate strings are a problem
> or that it's a good idea to send over a hundred patches using this
> method. But many people have explained that to Markus already and
> that's not the bigger picture which is about error handling and labels.
>
> What I like are labels that are necessary and self explanatory. Things
> like "goto unlock" are a good example, because we know we need to unlock
> and the goto tells us what the label does. Or here is another example:
>
> foo = alloc_foo();
> if (!foo)
> return -ENOMEM;
>
> bar = alloc_bar();
> if (!foo) {
> err = -ENOMEM;
> goto free_foo;
> }
>
> From reading the code, you know that you have to free foo and the label
> name is clear so you literally don't need to scroll down to the bottom
> of the function when you're reading this code. A bad label is like
> this:
>
> foo = alloc_foo();
> if (!foo)
> goto err;
>
> You're reading along and you're like "what happens at the err" label?
> So then you have to scroll down to the bottom and read the code, then
> you have to think about how the variables line up with the variables
> in the above code, then you have to scroll back and find your place
> again and by that point you've forgotten what you were doing when you
> started.
Thanks for the details! Much appreciated!
Regarding posts from Markus' I am well aware of the problems.
In my case, it hasn't been much of a hurdle, I simply ignore changes
that seems silly to me.
Kind regards
Uffe
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