linux-kernel - [PATCH 06/13] lib: extend the scope of small_const

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Message-Id: <20210316015424.1999082-7-yury.norov@gmail.com>
Date:   Mon, 15 Mar 2021 18:54:17 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>, linux-m68k@...ts.linux-m68k.org,
        linux-arch@...r.kernel.org, linux-sh@...r.kernel.org,
        Alexey Klimov <aklimov@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>, David Sterba <dsterba@...e.com>,
        Dennis Zhou <dennis@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Jianpeng Ma <jianpeng.ma@...el.com>,
        Joe Perches <joe@...ches.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Rich Felker <dalias@...c.org>,
        Stefano Brivio <sbrivio@...hat.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>
Subject: [PATCH 06/13] lib: extend the scope of small_const_nbits() macro

find_bit would also benefit from small_const_nbits() optimizations.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 include/asm-generic/bitsperlong.h | 9 +++++++++
 include/linux/bitmap.h            | 3 ---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/bitsperlong.h b/include/asm-generic/bitsperlong.h
index 3905c1c93dc2..96032f4f908f 100644
--- a/include/asm-generic/bitsperlong.h
+++ b/include/asm-generic/bitsperlong.h
@@ -23,4 +23,13 @@
 #define BITS_PER_LONG_LONG 64
 #endif
 
+#define SMALL_CONST(n) (__builtin_constant_p(n) && (unsigned long)(n) < BITS_PER_LONG)
+
+/*
+ * The valid number of bits for a bitmap to be small enough, or in other words,
+ * fit into a single machine word is 1 to BITS_PER_LONG inclusively. 0 is not a
+ * valid number for size, and most probably a sing of error.
+ */
+#define small_const_nbits(n) SMALL_CONST((n) - 1)
+
 #endif /* __ASM_GENERIC_BITS_PER_LONG */
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index adf7bd9f0467..bc13a890ecc1 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -224,9 +224,6 @@ extern int bitmap_print_to_pagebuf(bool list, char *buf,
  * so make such users (should any ever turn up) call the out-of-line
  * versions.
  */
-#define small_const_nbits(nbits) \
-	(__builtin_constant_p(nbits) && (nbits) <= BITS_PER_LONG && (nbits) > 0)
-
 static inline void bitmap_zero(unsigned long *dst, unsigned int nbits)
 {
 	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
-- 
2.25.1