Re: [PATCH v4 07/23] ata: libahci_platform: Convert to using devm bulk clocks API

Damien Le Moal
2022-06-16T00:24:19Z

On 2022/06/16 5:45, Serge Semin wrote:
[...]
>>> + hpriv->clks = devm_kzalloc(dev, sizeof(*hpriv->clks), GFP_KERNEL);
>>> + if (!hpriv->clks) {
>>> + rc = -ENOMEM;
>>> + goto err_out;
>>> + }
>>> + hpriv->clks->clk = devm_clk_get_optional(dev, NULL);
>
>>> + if (IS_ERR(hpriv->clks->clk)) {
>>> + rc = PTR_ERR(hpriv->clks->clk);
>>> + goto err_out;
>>> + } else if (hpriv->clks->clk) {
>>
>> Nit: the else is not needed here.
>
> Well, it depends on what you see behind it. I see many reasons to keep
> it and only one tiny reason to drop it. Keeping it will improve the
> code readability and maintainability like having a more natural
> execution flow representation, thus clearer read-flow (else part as
> exception to the if part), less modifications should the goto part is
> changed/removed, a more exact program flow representation can be used
> by the compiler for some internal optimizations, it's one line shorter
> than the case we no 'else' here. On the other hand indeed we can drop
> it since if the conditional statement is true, the code afterwards
> won't be executed due to the goto operator. But as I see it dropping
> the else operator won't improve anything, but vise-versa will worsen
> the code instead. So if I get to miss something please justify why you
> want it being dropped, otherwise I would rather preserve it.

An else after a goto or return is never necessary and in my opinion makes the
code harder to read. I am not interested in debating this in general anyway. For
this particular case, the code would be:

hpriv->clks->clk = devm_clk_get_optional(dev, NULL);
if (IS_ERR(hpriv->clks->clk)) {
/* Error path */
rc = PTR_ERR(hpriv->clks->clk);
goto err_out;
}

/* Normal path */
if (hpriv->clks->clk) {
...
}

Which in my opinion is a lot easier to understand compared to having to parse
the if/else if and figure out which case in that sequence is normal vs error.

As noted, this is a nit. If you really insist, keep that else if.

>
> -Sergey
>
>>
>>> + hpriv->clks->id = __clk_get_name(hpriv->clks->clk);
>>> + hpriv->n_clks = 1;
>>> }
>>> - hpriv->clks[i] = clk;
>>> }
>>>
>>> hpriv->ahci_regulator = devm_regulator_get(dev, "ahci");
>>
>>
>> --
>> Damien Le Moal
>> Western Digital Research

--
Damien Le Moal
Western Digital Research