Re: [PATCH] cxl/port: Fix port to pci device assumptions in read_cdat_data()

[Lukas Wunner <lukas@wunner.de>]

On Sat, Apr 22, 2023 at 10:35:02AM +0200, Lukas Wunner wrote:
> I note however that before af0a6c3587dc, xa_for_each() was run on an
> xarray which was not initialized with xa_init() on non-pci cxl ports.
> (xa_init() was run from cxl_pci_probe() -> devm_cxl_pci_create_doe()
> but xa_for_each() was run from read_cdat_data() -> find_cdat_doe()
> for non-pci cxl ports as well.)
> 
> Hence can't this crash prior to af0a6c3587dc as well?

After taking another look with a fresh pair of eyeballs I think
you may see splats with CONFIG_DEBUG_LOCK_ALLOC=y (even prior to
af0a6c3587dc on non-pci cxl devices) due to the missing xa_init().

struct cxl_dev_state is kzalloc'ed and with CONFIG_DEBUG_LOCK_ALLOC=n,
the members of struct xarray all seem to be just zeroed by xa_init().
So no harm no foul.  But that's not the case with CONFIG_DEBUG_LOCK_ALLOC=y
because spinlock_t contains non-zero data.

Thanks,

Lukas