mm/sparse.c: make sparse_init_one_section void and remove check

sparse_init_one_section() is being called from two sites: sparse_init()
and sparse_add_one_section().  The former calls it from a
for_each_present_section_nr() loop, and the latter marks the section as
present before calling it.  This means that when
sparse_init_one_section() gets called, we already know that the section
is present.  So there is no point to double check that in the function.

This removes the check and makes the function void.

[ross.zwisler@linux.intel.com: fix error path in sparse_add_one_section]
  Link: http://lkml.kernel.org/r/20180706190658.6873-1-ross.zwisler@linux.intel.com
[ross.zwisler@linux.intel.com: simplification suggested by Oscar]
  Link: http://lkml.kernel.org/r/20180706223358.742-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20180702154325.12196-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/sparse.c

@@ -257,19 +257,14 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn
 	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 }
 
-static int __meminit sparse_init_one_section(struct mem_section *ms,
+static void __meminit sparse_init_one_section(struct mem_section *ms,
 		unsigned long pnum, struct page *mem_map,
 		unsigned long *pageblock_bitmap)
 {
-	if (!present_section(ms))
-		return -EINVAL;
-
 	ms->section_mem_map &= ~SECTION_MAP_MASK;
 	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
 							SECTION_HAS_MEM_MAP;
  	ms->pageblock_flags = pageblock_bitmap;
-
-	return 1;
 }
 
 unsigned long usemap_size(void)
@@ -760,6 +755,7 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
 	ret = sparse_index_init(section_nr, pgdat->node_id);
 	if (ret < 0 && ret != -EEXIST)
 		return ret;
+	ret = 0;
 	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap);
 	if (!memmap)
 		return -ENOMEM;
@@ -786,12 +782,11 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
 #endif
 
 	section_mark_present(ms);
-
-	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
+	sparse_init_one_section(ms, section_nr, memmap, usemap);
 
 out:
 	pgdat_resize_unlock(pgdat, &flags);
-	if (ret <= 0) {
+	if (ret < 0) {
 		kfree(usemap);
 		__kfree_section_memmap(memmap, altmap);
 	}