linux-kernel - [PATCH v4 3/8] mm/memory_hotplug: guard more declarations by CONFIG_MEMORY

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Date:   Fri, 11 Sep 2020 12:34:54 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-hyperv@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-acpi@...r.kernel.org, linux-nvdimm@...ts.01.org,
        linux-s390@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Baoquan He <bhe@...hat.com>,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH v4 3/8] mm/memory_hotplug: guard more declarations by CONFIG_MEMORY_HOTPLUG

We soon want to pass flags via a new type to add_memory() and friends.
That revealed that we currently don't guard some declarations by
CONFIG_MEMORY_HOTPLUG.

While some definitions could be moved to different places, let's keep it
minimal for now and use CONFIG_MEMORY_HOTPLUG for all functions only
compiled with CONFIG_MEMORY_HOTPLUG.

Wrap sparse_decode_mem_map() into CONFIG_MEMORY_HOTPLUG, it's only
called from CONFIG_MEMORY_HOTPLUG code.

While at it, remove allow_online_pfn_range(), which is no longer around,
and mhp_notimplemented(), which is unused.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Wei Yang <richardw.yang@...ux.intel.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 include/linux/memory_hotplug.h | 12 +++---------
 mm/sparse.c                    |  2 ++
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 51a877fec8da8..1504b4d5ae6ce 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -247,13 +247,6 @@ static inline void zone_span_writelock(struct zone *zone) {}
 static inline void zone_span_writeunlock(struct zone *zone) {}
 static inline void zone_seqlock_init(struct zone *zone) {}
 
-static inline int mhp_notimplemented(const char *func)
-{
-	printk(KERN_WARNING "%s() called, with CONFIG_MEMORY_HOTPLUG disabled\n", func);
-	dump_stack();
-	return -ENOSYS;
-}
-
 static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
 {
 }
@@ -344,6 +337,7 @@ static inline void __remove_memory(int nid, u64 start, u64 size) {}
 extern void set_zone_contiguous(struct zone *zone);
 extern void clear_zone_contiguous(struct zone *zone);
 
+#ifdef CONFIG_MEMORY_HOTPLUG
 extern void __ref free_area_init_core_hotplug(int nid);
 extern int __add_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
@@ -364,8 +358,8 @@ extern void sparse_remove_section(struct mem_section *ms,
 		unsigned long map_offset, struct vmem_altmap *altmap);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
 					  unsigned long pnum);
-extern bool allow_online_pfn_range(int nid, unsigned long pfn, unsigned long nr_pages,
-		int online_type);
 extern struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
 		unsigned long nr_pages);
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
 #endif /* __LINUX_MEMORY_HOTPLUG_H */
diff --git a/mm/sparse.c b/mm/sparse.c
index b25ad8e648392..7bd23f9d6cef6 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -312,6 +312,7 @@ static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long p
 	return coded_mem_map;
 }
 
+#ifdef CONFIG_MEMORY_HOTPLUG
 /*
  * Decode mem_map from the coded memmap
  */
@@ -321,6 +322,7 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn
 	coded_mem_map &= SECTION_MAP_MASK;
 	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
 }
+#endif /* CONFIG_MEMORY_HOTPLUG */
 
 static void __meminit sparse_init_one_section(struct mem_section *ms,
 		unsigned long pnum, struct page *mem_map,
-- 
2.26.2