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SubjectRe: [PATCH] arm pl011 serial: support multi-irq request
On Tue, Jun 29, 2021 at 07:32:36PM +0800, Bing Fan wrote:
> hello,
>
> replied as below.
>
> and new patch is at the bottom.

Please submit this properly as the documentation says to do so, I can't
take an attachment :(

> > > + struct amba_device *amba_dev = (struct amba_device *)uap->port.dev;
> > Are you sure you can just cast this like this? Did you test this?
>
>
> Yes, i have tested and applied in my project.
>
> The function pl011_probe calls pl011_setup_port with &amba_dev->dev and uap
> params;
>
> and pl011_setup_port set uap->port.dev to the address of amba_dev->dev;
>
> the two structs' relationship is:
>
>     struct amba_device {
>
>         struct device dev;
>
>         ……
>
>     };
>
> When pointer(uap->port.dev) points to amba_dev->dev address, the momery
> actully stores
>
> content of struct amba_device; so the cast assignment can be forced to
> amba_dev.

That is now how this should work, use the correct container_of() cast
instead. That will always work no matter where struct device is in the
structure. You got lucky here :)

> > > +
> > > + if (!amba_dev)
> > > + return -1;
> > Do not make up error numbers, return a specific -ERR* value.
>
> changed to "return -ENODEV"

So this changed the logic of this function, is that ok?

> >
> > And how can this happen?
>
> The function pl011_setup_port isn't called, event pl011_probe isn't called.

And how can that ever happen?


thanks,

greg k-h

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