Messages in this thread | | | Date | Tue, 29 Aug 2023 16:59:30 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH RFC v2 10/18] cxl/mem: Handle DCD add and release capacity events. |
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On Mon, 28 Aug 2023 22:21:01 -0700 Ira Weiny <ira.weiny@intel.com> wrote:
> A Dynamic Capacity Device (DCD) utilizes events to signal the host about > the changes to the allocation of Dynamic Capacity (DC) extents. The > device communicates the state of DC extents through an extent list that > describes the starting DPA, length, and meta data of the blocks the host > can access. > > Process the dynamic capacity add and release events. The addition or > removal of extents can occur at any time. Adding asynchronous memory is > straight forward. Also remember the host is under no obligation to > respond to a release event until it is done with the memory. Introduce > extent kref's to handle the delay of extent release. > > In the case of a force removal, access to the memory will fail and may > cause a crash. However, the extent tracking object is preserved for the > region to safely tear down as long as the memory is not accessed. > > Signed-off-by: Navneet Singh <navneet.singh@intel.com> > Co-developed-by: Ira Weiny <ira.weiny@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> Minor stuff inline.
> +static int cxl_prepare_ext_list(struct cxl_mbox_dc_response **res, > + int *n, struct range *extent) > +{ > + struct cxl_mbox_dc_response *dc_res; > + unsigned int size; > + > + if (!extent) > + size = struct_size(dc_res, extent_list, 0);
This is confusing as if you did have *n > 0 I'd kind of expect this to just not extend the list rather than shortening it. Now I guess that never happens, but locally it looks odd.
Maybe just handle that case in a separate function as it doesn't share much code with the case where there is an extent and I would assume we always know at the caller which one we want.
> + else > + size = struct_size(dc_res, extent_list, *n + 1);
Might be clearer with a local variable for the number of extents.
extents_count = *n;
if (extent) extents_count++;
size = struct_size(dc_res, extent_list, extents_count);
Though I'm not sure that really helps. Maybe this will just need to be a little confusing :)
> + > + dc_res = krealloc(*res, size, GFP_KERNEL); > + if (!dc_res) > + return -ENOMEM; > + > + if (extent) { > + dc_res->extent_list[*n].dpa_start = cpu_to_le64(extent->start); > + memset(dc_res->extent_list[*n].reserved, 0, 8); > + dc_res->extent_list[*n].length = cpu_to_le64(range_len(extent)); > + (*n)++; > + } > + > + *res = dc_res; > + return 0; > +}
> + > +/* Returns 0 if the event was handled successfully. */ > +static int cxl_handle_dcd_event_records(struct cxl_memdev_state *mds, > + struct cxl_event_record_raw *rec) > +{ > + struct dcd_event_dyn_cap *record = (struct dcd_event_dyn_cap *)rec; > + uuid_t *id = &rec->hdr.id; > + int rc; > + > + if (!uuid_equal(id, &dc_event_uuid)) > + return -EINVAL; > + > + switch (record->data.event_type) { > + case DCD_ADD_CAPACITY: > + rc = cxl_handle_dcd_add_event(mds, &record->data.extent); > + break;
I guess it might not be consistent with local style... return cxl_handle_dcd_add_event() etc
> + case DCD_RELEASE_CAPACITY: > + case DCD_FORCED_CAPACITY_RELEASE: > + rc = cxl_handle_dcd_release_event(mds, &record->data.extent); > + break; > + default: > + return -EINVAL; > + } > + > + return rc; > +} > +
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