On Wed, 07 Mar 2018, Charles Keepax wrote:

> On Wed, Mar 07, 2018 at 01:28:12PM +0000, Lee Jones wrote:
> > On Tue, 20 Feb 2018, Charles Keepax wrote:
> > > + if (IS_ERR(pdata->reset)) {
> > > +         ret = PTR_ERR(pdata->reset);
> > > +         switch (ret) {
> > > +         case -ENOENT:
> > > +         case -ENOSYS:
> > > +                 break;
> > > +         case -EPROBE_DEFER:
> > > +                 return ret;
> > > +         default:
> > > +                 dev_err(arizona->dev, "Reset GPIO malformed: %d\n",
> > > +                         ret);
> > > +                 break;
> > > +         }
> > 
> > I haven't seen a switch statement used in the error handling path
> > before.  There is probably good reason for that.
> > 
> 
> There are a fair few of them "grep -rI "switch (ret)" | wc -l" ==
> 205. Although to be fair that has rarely been an argument in
> somethings favour.

I didn't say "it has never been done", just that I hadn't seen it.

Besides, 205 uses is a very small amount in kernel code:

`git grep "if (ret" | wc -l` == 74710

> > What is the 'default' case?  -EINVAL?
> > 
> 
> I would guess most of the time yes, but I would rather not assume
> that. I can redo this as if's if you prefer it that way? The if is
> slightly less lines although I do think the switch is much
> clearer as to intent.
> 
> if (ret == -EPROBE_DEFER) {
>       return ret;
> } else if (ret != -ENOENT && ret != -ENOSYS {
>       dev_err(arizona->dev, ....);
> }

I don't know enough about the API to see why -ENOENT and -ENOSYS do
not deserve error messages.

What do the other users of the API do?

-- 
Lee Jones
Linaro Services Technical Lead
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