The patch titled
Subject: lib/memweight.c: open code bitmap_weight()
has been added to the -mm tree. Its filename is
lib-memweightc-open-codes-bitmap_weight.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-memweightc-open-codes-bitmap_weight.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-memweightc-open-codes-bitmap_weight.patch
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------------------------------------------------------
From: Denis Efremov <efremov@xxxxxxxxx>
Subject: lib/memweight.c: open code bitmap_weight()
Open code the bitmap_weight() call. The direct invocation of
hweight_long() permits removal of the BUG_ON and excessive "longs to bits,
bits to longs" conversion.
BUG_ON was required to check that bitmap_weight() will return a correct
value, i.e. the computed weight will fit the int type of the return
value. With this patch memweight() controls the computation directly with
size_t type everywhere. Thus, the BUG_ON becomes unnecessary.
Total size reduced:
./scripts/bloat-o-meter lib/memweight.o.old lib/memweight.o.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10)
Function old new delta
memweight 162 152 -10
Link: http://lkml.kernel.org/r/20190824100102.1167-1-efremov@xxxxxxxxx
Signed-off-by: Erdem Tumurov <erdemus@xxxxxxxxx>
Signed-off-by: Vladimir Shelekhov <vshel@xxxxxxxxxx>
Signed-off-by: Denis Efremov <efremov@xxxxxxxxx>
Co-developed-by: Erdem Tumurov <erdemus@xxxxxxxxx>
Co-developed-by: Vladimir Shelekhov <vshel@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/memweight.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/lib/memweight.c~lib-memweightc-open-codes-bitmap_weight
+++ a/lib/memweight.c
@@ -20,11 +20,13 @@ size_t memweight(const void *ptr, size_t
longs = bytes / sizeof(long);
if (longs) {
- BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
- ret += bitmap_weight((unsigned long *)bitmap,
- longs * BITS_PER_LONG);
+ const unsigned long *bitmap_long =
+ (const unsigned long *)bitmap;
+
bytes -= longs * sizeof(long);
- bitmap += longs * sizeof(long);
+ for (; longs > 0; longs--, bitmap_long++)
+ ret += hweight_long(*bitmap_long);
+ bitmap = (const unsigned char *)bitmap_long;
}
/*
* The reason that this last loop is distinct from the preceding
_
Patches currently in -mm which might be from efremov@xxxxxxxxx are
lib-memweightc-open-codes-bitmap_weight.patch
