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Dan Williams authored
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 <rrichter@amd.com> Link: https://lore.kernel.org/r/166993041773.1882361.16444301376147207609.stgit@dwillia2-xfh.jf.intel.comReviewed-by:
Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by:
Dan Williams <dan.j.williams@intel.com>
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