Re: [NDCTL PATCH v2] cxl: Add helper function to verify port is in memdev hierarchy

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

On 7/14/25 3:27 PM, Verma, Vishal L wrote:
> On Fri, 2025-07-11 at 15:33 -0700, Dave Jiang wrote:
>> 'cxl enable-port -m' uses cxl_port_get_dport_by_memdev() to find the
>> memdevs that are associated with a port in order to enable those
>> associated memdevs. When the kernel switch to delayed dport
>> initialization by enumerating the dports during memdev probe, the
>> dports are no longer valid until the memdev is probed. This means
>> that cxl_port_get_dport_by_memdev() will not find any memdevs under
>> the port.
>>
>> Add a new helper function cxl_port_is_memdev_hierarchy() that checks if a
> 
> Stale commit message - since the actual helper is called
> cxl_memdev_is_port_ancestor() ?

Ooops. Maybe Alison can fix it up when she applies if there are no other changes.

> 
>> port is in the memdev hierarchy via the memdev->host_path where the sysfs
>> path contains all the devices in the hierarchy. This call is also backward
>> compatible with the old behavior.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
>> ---
>> v2:
>> - Remove usages of cxl_port_get_dport_by_memdev() and add documentation to explain
>>   when cxl_port_get_dport_by_memdev() should be used. (Alison)
>> ---
>>  Documentation/cxl/lib/libcxl.txt |  5 +++++
>>  cxl/filter.c                     |  2 +-
>>  cxl/lib/libcxl.c                 | 31 +++++++++++++++++++++++++++++++
>>  cxl/lib/libcxl.sym               |  5 +++++
>>  cxl/libcxl.h                     |  3 +++
>>  cxl/port.c                       |  4 ++--
>>  6 files changed, 47 insertions(+), 3 deletions(-)