On Thu, 01 Dec 2022 13:33:37 -0800 Dan Williams <dan.j.willi...@intel.com> wrote:
> The three objects 'struct cxl_nvdimm_bridge', 'struct cxl_nvdimm', and > 'struct cxl_pmem_region' manage CXL persistent memory resources. The > bridge represents base platform resources, the nvdimm represents one or > more endpoints, and the region is a collection of nvdimms that > contribute to an assembled address range. > > Their relationship is such that a region is torn down if any component > endpoints are removed. All regions and endpoints are torn down if the > foundational bridge device goes down. > > A workqueue was deployed to manage these interdependencies, but it is > difficult to reason about, and fragile. A recent attempt to take the CXL > root device lock in the cxl_mem driver was reported by lockdep as > colliding with the flush_work() in the cxl_pmem flows. > > Instead of the workqueue, arrange for all pmem/nvdimm devices to be torn > down immediately and hierarchically. A similar change is made to both > the 'cxl_nvdimm' and 'cxl_pmem_region' objects. For bisect-ability both > changes are made in the same patch which unfortunately makes the patch > bigger than desired. > > Arrange for cxl_memdev and cxl_region to register a cxl_nvdimm and > cxl_pmem_region as a devres release action of the bridge device. > Additionally, include a devres release action of the cxl_memdev or > cxl_region device that triggers the bridge's release action if an endpoint > exits before the bridge. I.e. this allows either unplugging the bridge, > or unplugging and endpoint to result in the same cleanup actions. > > To keep the patch smaller the cleanup of the now defunct workqueue > infrastructure is saved for a follow-on patch. > > Tested-by: Robert Richter <rrich...@amd.com> > Signed-off-by: Dan Williams <dan.j.willi...@intel.com> I wouldn't say it's the most confident review tag I've ever given, but I've taken another look at it and couldn't identify any remaining issues... So with that in mind Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
