Re: [RFC PATCH] phylib: mdio: handle register/unregister/registersequence

[boris brezillon]

On 22/08/2013 17:27, Greg Kroah-Hartman wrote:
> On Thu, Aug 22, 2013 at 02:33:56PM +0200, Boris BREZILLON wrote:
> > Hello,
> >
> > This patch is a proposal to support the register/unregister/register
> > sequence on a given mdio bus.
> >
> > I use the register/unregister/register sequence to add a fallback when the
> > of_mdiobus_register (this function calls mdiobus_register with phy_mask
> > set to ~0) does not register any phy device (because the device tree does
> > not define any phy).
> > In this case I call mdiobus_unregister and then call mdiobus_register with
> > a phy_mask set to 0 to trigger a full mdio bus scan.
> >
> > I'm not sure this is the right way to do it (this is why I added RFC in the
> > subject).
> >
> > Could someone help me figuring out what I should use to implement my fallback ?
> >
> > 1) use the register/unregister/register sequence
> That will not work.  Well, you might think it would work, but then
> things randomly start breaking later on.  Try it with the
> KOBJECT_DELAYED_DESTROY build option in linux-next, and watch things go
> "boom" :)
>
> The rule is, you should never register a kobject/struct device that you
> have previously unregistered before, as you really don't know if
> unregistering has finished or not.

Thanks for your answer.

> sorry,
>
> greg k-h

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