[PATCH v4 05/13] mm: cleanup sparse_init_one_section() return value

[Dan Williams]

We mark and check that the section is present under a spin_lock() in
sparse_add_one_section(), so the lock ensures it will not change between
those 2 events. Also, we do not check the -EBUSY return value in
sparse_init(). Just make sparse_init_one_section() return void and clean
up the error handling.

Cc: Michal Hocko <mho...@suse.com>
Cc: Vlastimil Babka <vba...@suse.cz>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Logan Gunthorpe <log...@deltatee.com>
Cc: Mel Gorman <mgor...@techsingularity.net>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Stephen Bates <stephen.ba...@microsemi.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 mm/sparse.c |   21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index d0d4c005dc60..886f666ebe35 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -231,19 +231,14 @@ 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,
                struct mem_section_usage *usage)
 {
-       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->usage = usage;
-
-       return 1;
 }
 
 unsigned long usemap_size(void)
@@ -690,11 +685,6 @@ static void free_map_bootmem(struct page *memmap)
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
-/*
- * returns the number of sections whose mem_maps were properly
- * set.  If this is <=0, then that means that the passed-in
- * map was not consumed and must be freed.
- */
 int __meminit sparse_add_one_section(struct zone *zone, unsigned long 
start_pfn)
 {
        unsigned long section_nr = pfn_to_section_nr(start_pfn);
@@ -725,7 +715,7 @@ int __meminit sparse_add_one_section(struct zone *zone, 
unsigned long start_pfn)
 
        ms = __pfn_to_section(start_pfn);
        if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
-               ret = -EEXIST;
+               ret = -EBUSY;
                goto out;
        }
 
@@ -733,15 +723,16 @@ int __meminit sparse_add_one_section(struct zone *zone, 
unsigned long start_pfn)
 
        ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
-       ret = sparse_init_one_section(ms, section_nr, memmap, usage);
+       sparse_init_one_section(ms, section_nr, memmap, usage);
 
 out:
        pgdat_resize_unlock(pgdat, &flags);
-       if (ret <= 0) {
+       if (ret < 0 && ret != -EEXIST) {
                kfree(usage);
                __kfree_section_memmap(memmap);
+               return ret;
        }
-       return ret;
+       return 0;
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE

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