Le 14/09/2020 à 10:31, David Hildenbrand a écrit :
static int register_mem_sect_under_node_hotplug(struct memory_block *mem_blk, void *arg) { const int nid = *(int *)arg; int ret;
/* Hotplugged memory has no holes and belongs to a single node. */ mem_blk->nid = nid; ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, &mem_blk->dev.kobj, kobject_name(&mem_blk->dev.kobj)); if (ret) returnr et; return sysfs_create_link_nowarn(&mem_blk->dev.kobj, &node_devices[nid]->dev.kobj, kobject_name(&node_devices[nid]->dev.kobj));
}
Cleaner, right? :) No unnecessary checks.
I tend to agree here, I like more a simplistic version for hotplug.
... and while we're at it, we should rename register_mem_sect_under_node to something like "register_memory_block_under_node" - "section" is a legacy leftover here.
We could factor out both sysfs_create_link_nowarn() calls into something like "do_register_memory_block_under_node" or similar, to minimize code duplication.
One could argue if link_mem_section_hotplug() would be better than passing around the context.
I am not sure if I would duplicate the code there. We could just pass the pointer of the function we want to call to link_mem_sections? either register_mem_sect_under_node_hotplug or register_mem_sect_under_node_early? Would not that be clean and clear enough?
I don't particularly like passing around function pointers where it can be avoided (e.g., here exporting 3 functions now instead 1). Makes the interface harder to get IMHO. But I don't really care about that interface, easy to change later on.
This would lead to the following.
Do everyone agree?
diff --git a/drivers/base/node.c b/drivers/base/node.c index 508b80f6329b..444808a7c9b6 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -761,9 +761,32 @@ static int __ref get_nid_for_pfn(unsigned long pfn) return pfn_to_nid(pfn); }
+static int do_register_memory_block_under_node(int nid, + struct memory_block *mem_blk) +{ + int ret; + + /* + * If this memory block spans multiple nodes, we only indicate + * the last processed node. + */ + mem_blk->nid = nid; + + ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, + &mem_blk->dev.kobj, + kobject_name(&mem_blk->dev.kobj)); + if (ret) + return ret; + + return sysfs_create_link_nowarn(&mem_blk->dev.kobj, + &node_devices[nid]->dev.kobj, + kobject_name(&node_devices[nid]->dev.kobj)); + +} + /* register memory section under specified node if it spans that node */ -static int register_mem_sect_under_node(struct memory_block *mem_blk, - void *arg) +static int register_mem_block_under_node_early(struct memory_block *mem_blk, + void *arg) { unsigned long memory_block_pfns = memory_block_size_bytes() / PAGE_SIZE; unsigned long start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); @@ -785,38 +808,35 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk, }
/* - * We need to check if page belongs to nid only for the boot - * case, during hotplug we know that all pages in the memory - * block belong to the same node. + * We need to check if page belongs to nid only at the boot + * case because node's ranges can be interleaved. */ - if (system_state == SYSTEM_BOOTING) { - page_nid = get_nid_for_pfn(pfn); - if (page_nid < 0) - continue; - if (page_nid != nid) - continue; - } - - /* - * If this memory block spans multiple nodes, we only indicate - * the last processed node. - */ - mem_blk->nid = nid; + page_nid = get_nid_for_pfn(pfn); + if (page_nid < 0) + continue; + if (page_nid != nid) + continue;
- ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj, - &mem_blk->dev.kobj, - kobject_name(&mem_blk->dev.kobj)); + ret = do_register_memory_block_under_node(nid, mem_blk); if (ret) return ret; - - return sysfs_create_link_nowarn(&mem_blk->dev.kobj, - &node_devices[nid]->dev.kobj, - kobject_name(&node_devices[nid]->dev.kobj)); } /* mem section does not span the specified node */ return 0; }
+/* + * During hotplug we know that all pages in the memory block belong to the same + * node. + */ +static int register_mem_block_under_node_hotplug(struct memory_block *mem_blk, + void *arg) +{ + int nid = *(int *)arg; + + return do_register_memory_block_under_node(nid, mem_blk); +} + /* * Unregister a memory block device under the node it spans. Memory blocks * with multiple nodes cannot be offlined and therefore also never be removed. @@ -832,11 +852,19 @@ void unregister_memory_block_under_nodes(struct memory_block *mem_blk) kobject_name(&node_devices[mem_blk->nid]->dev.kobj)); }
-int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn) +int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn, + enum memplug_context context) { + walk_memory_blocks_func_t func; + + if (context == MEMPLUG_HOTPLUG) + func = register_mem_block_under_node_hotplug; + else + func = register_mem_block_under_node_early; + return walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn), (void *)&nid, - register_mem_sect_under_node); + func); }
#ifdef CONFIG_HUGETLBFS