Re: [PATCH] cxl/region: Add decoder check to check_commit_order()

[Dave Jiang <dave.jiang@intel.com>]

On 4/30/25 10:29 PM, dan.j.williams@intel.com wrote:
> Li Ming wrote:
>> On 5/1/2025 5:36 AM, Dave Jiang wrote:
>>> check_commit_order() attempts to convert a device to a decoder without
>>> making sure the device is a decoder. So far this has been working due
>>> to pure luck. Issue discovered while doing deferred dport probing when
>>> child ports are now in the midst of decoders due to ordering change
>>> of child port additions. Add a check before attempting to do decoder
>>> conversion.
>>>
>>> Fixes: 105b6235ad0f ("cxl/port: Prevent out-of-order decoder allocation")
>>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>>
>> I also have a patch for this issue during I worked on deferred dport probing.
>>
>> https://lore.kernel.org/linux-cxl/20250107035708.1134954-4-ming.li@zohomail.com/
>>
>> I am not sure if we should define it as a bug, my understanding is
>> that it will never happen with current implementation, it only happens
>> when we are trying to delay the switch decoders initialization.
> 
> Agree. This is not a fix. The current implementation is lucky that ports
> are always registered after decoders. So there is zero exposure to this
> issue for current kernels.
> 
> Dave, please just include this as a prep patch in the same series that
> invalidates the port child device ordering assumption.

will do