Re: [PATCH v2 1/1] cxl/port: Avoid missing port component registers setup

[Davidlohr Bueso <dave@stgolabs.net>]

On Sun, 28 Sep 2025, Li Ming wrote:

>port->nr_dports is used to represent how many dports added to the cxl
>port, it will increase in add_dport() when a new dport is being added to
>the cxl port, but it will not be reduced when a dport is removed from
>the cxl port.
>
>Currently, when the first dport is added to a cxl port, it will trigger
>component registers setup on the cxl port, the implementation is using
>port->nr_dports to confirm if the dport is the first dport.
>
>A corner case here is that adding dport could fail after port->nr_dports
>updating and before checking port->nr_dports for component registers
>setup. If the failure happens during the first dport attaching, it will
>cause that CXL subsystem has not chance to execute component registers
>setup for the cxl port. the failure flow like below:
>
>port->nr_dports = 0
>dport 1 adding to the port:
>	add_dport()	# port->nr_dports: 1
>	failed on devm_add_action_or_reset() or sysfs_create_link()
>	return error	# port->nr_dports: 1
>dport 2 adding to the port:
>	add_dport()	# port->nr_dports: 2
>	no failure
>	skip component registers setup because of port->nr_dports is 2
>
>The solution here is that moving component registers setup closer to
>add_dport(), so if add_dport() is executed correctly for the first
>dport, component registers setup on the port will be executed
>immediately after that.

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>