linux-kernel - Re: [PATCH] fix a code style in drivers/char/virtio

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Message-ID: <AANLkTinkel3TW8cCY3YCIw_savLuwcQKR67ebX7EmmSU@mail.gmail.com>
Date:	Tue, 18 May 2010 14:41:35 +0800
From:	Steven Liu <lingjiujianke@...il.com>
To:	Amit Shah <amit.shah@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH] fix a code style in drivers/char/virtio_console.c

okay, i see, thanks for your regards :)

2010/5/18 Amit Shah <amit.shah@...hat.com>:
> Hello,
>
> On (Tue) May 18 2010 [13:41:29], Steven Liu wrote:
>> Hi, Amit,
>>
>>     if 'err' initialised in this path, it needn't do err = -ENOMEM
>> after,isn't it?
>
> What I mean is if we later add some code that just does:
>
>        if (err)
>                goto fail;
>
> then 'ret' can be -ENOMEM, as it was initialised to, which would be
> fine. But if a later patch adds something like:
>
> +       ret = -EIO;
> +       err = ...
> +       if (err)
> +               goto fail;
> +
>        err = ...
>        if (err)
>                goto fail;
>
> In this case, the 2nd if() would now return EIO instead of ENOMEM as
> earlier.
>
> Also, this style of coding can prevent uninitialised usage of 'ret', eg:
>
>
>        int ret;
>
>        if (err)
>                goto fail;
>
> fail:
>        return ret;
>
> In this case, the compiler will warn about 'ret' being used
> uninitialised.
>
> This is just a coding style issue. I had initially coded it the way your
> patch does, but Rusty asked me to change that and I like this new style
> better: there's less scope for surprises.
>
>                Amit
>
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