linux-kernel - [PATCH 2/2] lib/bitmap.c: guard exotic bitmap functions by CONFIG

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Date:   Fri, 29 Mar 2019 21:53:51 +0100
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Yury Norov <ynorov@...iumnetworks.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] lib/bitmap.c: guard exotic bitmap functions by CONFIG_NUMA

The bitmap_remap, _bitremap, _onto and _fold functions are only used,
via their node_ wrappers, in mm/mempolicy.c, which is only built for
CONFIG_NUMA. The helper bitmap_ord_to_pos used by these functions is
global, but its only external caller is node_random() in lib/nodemask.c,
which is also guarded by CONFIG_NUMA.

For !CONFIG_NUMA:

add/remove: 0/6 grow/shrink: 0/0 up/down: 0/-621 (-621)
Function                                     old     new   delta
bitmap_pos_to_ord                             20       -     -20
bitmap_ord_to_pos                             70       -     -70
bitmap_bitremap                               81       -     -81
bitmap_fold                                  113       -    -113
bitmap_onto                                  123       -    -123
bitmap_remap                                 214       -    -214
Total: Before=4776, After=4155, chg -13.00%

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 lib/bitmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index 66421f304f7d..3f3b8051f342 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -649,6 +649,7 @@ int bitmap_parselist_user(const char __user *ubuf,
 EXPORT_SYMBOL(bitmap_parselist_user);
 
 
+#ifdef CONFIG_NUMA
 /**
  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
  *	@buf: pointer to a bitmap
@@ -952,6 +953,7 @@ void bitmap_fold(unsigned long *dst, const unsigned long *orig,
 	for_each_set_bit(oldbit, orig, nbits)
 		set_bit(oldbit % sz, dst);
 }
+#endif /* CONFIG_NUMA */
 
 /*
  * Common code for bitmap_*_region() routines.
-- 
2.20.1