Re: [PATCH v2 05/15] spi: Remove code duplication in spi_add_device_locked()

Andy Shevchenko
2023-07-11T12:48:23Z

On Tue, Jul 11, 2023 at 02:01:33PM +0200, Sebastian Reichel wrote:
> On Tue, Jul 11, 2023 at 02:06:20PM +0300, Andy Shevchenko wrote:
> > On Mon, Jul 10, 2023 at 06:16:22PM +0100, Mark Brown wrote:
> > > On Mon, Jul 10, 2023 at 06:49:22PM +0300, Andy Shevchenko wrote:

...

> > > > - struct device *dev = ctlr->dev.parent;
> > > > -
> > > > - /* Chipselects are numbered 0..max; validate. */
> > > > - if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
> > > > - dev_err(dev, "cs%d >= max %d\n", spi_get_chipselect(spi, 0),
> > > > - ctlr->num_chipselect);
> > > > - return -EINVAL;
> > > > - }
> > > > -
> > > > - /* Set the bus ID string */
> > > > - spi_dev_set_name(spi);
> > >
> > > I see that this is duplicating spi_add_device() (and we really could do
> > > better with code sharing there I think) but I can't immediately see
> > > where the duplication that's intended to be elimiated is here - where
> > > else in the one call path that spi_add_device_locked() has would we do
> > > the above? Based on the changelog I was expecting to see some
> > > duplicated code in the function itself.
> >
> > Oh, by some reason Sebastian wasn't in this rather long Cc list.
> > Added him.
> >
> > Reading again I don't see any useful explanation why that piece of code has to
> > be duplicated among these two functions. It's 100% a copy.
> >
> > Sebastian, can you shed some light here?
>
> The patch in this thread is obviously wrong. It results in the
> checks never beeing called for spi_add_device_locked(). The copy is
> in spi_add_device() and those two are not calling into each other.

Ah, now I see, I missed __ in the name.
Thank you for opening my eyes!

> But it should be fine to move the code to the start of
> __spi_add_device(), which allows removing the duplication. In that
> case the code will be run with the add_lock held, which is probably
> what I was worried about two years ago. Looking at it again, the
> lock is held anyways in case of spi_add_device_locked().

Right, I will re-do that.

--
With Best Regards,
Andy Shevchenko