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From: Yury Norov <yury.norov@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Yury Norov <yury.norov@gmail.com>,
	linux-m68k@lists.linux-m68k.org, linux-arch@vger.kernel.org,
	linux-sh@vger.kernel.org, Alexey Klimov <aklimov@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>, David Sterba <dsterba@suse.com>,
	Dennis Zhou <dennis@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Jianpeng Ma <jianpeng.ma@intel.com>,
	Joe Perches <joe@perches.com>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Rich Felker <dalias@libc.org>,
	Stefano Brivio <sbrivio@redhat.com>,
	Wei Yang <richard.weiyang@linux.alibaba.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Yoshinori Sato <ysato@users.sourceforge.jp>
Subject: [PATCH 10/12] lib: add fast path for find_first_*_bit() and find_last_bit()
Date: Sun, 21 Mar 2021 14:54:55 -0700	[thread overview]
Message-ID: <20210321215457.588554-11-yury.norov@gmail.com> (raw)
In-Reply-To: <20210321215457.588554-1-yury.norov@gmail.com>

Similarly to bitmap functions, users would benefit if we'll handle
a case of small-size bitmaps that fit into a single word.

While here, move the find_last_bit() declaration to bitops/find.h
where other find_*_bit() functions sit.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
---
 include/asm-generic/bitops/find.h | 50 ++++++++++++++++++++++++++++---
 include/linux/bitops.h            | 12 --------
 lib/find_bit.c                    | 12 ++++----
 3 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 4148c74a1e4d..0d132ee2a291 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -5,6 +5,9 @@
 extern unsigned long _find_next_bit(const unsigned long *addr1,
 		const unsigned long *addr2, unsigned long nbits,
 		unsigned long start, unsigned long invert, unsigned long le);
+extern unsigned long _find_first_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
+extern unsigned long _find_last_bit(const unsigned long *addr, unsigned long size);
 
 #ifndef find_next_bit
 /**
@@ -102,8 +105,17 @@ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
  * Returns the bit number of the first set bit.
  * If no bits are set, returns @size.
  */
-extern unsigned long find_first_bit(const unsigned long *addr,
-				    unsigned long size);
+static inline
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+	if (small_const_nbits(size)) {
+		unsigned long val = *addr & GENMASK(size - 1, 0);
+
+		return val ? __ffs(val) : size;
+	}
+
+	return _find_first_bit(addr, size);
+}
 
 /**
  * find_first_zero_bit - find the first cleared bit in a memory region
@@ -113,8 +125,17 @@ extern unsigned long find_first_bit(const unsigned long *addr,
  * Returns the bit number of the first cleared bit.
  * If no bits are zero, returns @size.
  */
-extern unsigned long find_first_zero_bit(const unsigned long *addr,
-					 unsigned long size);
+static inline
+unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+	if (small_const_nbits(size)) {
+		unsigned long val = *addr | ~GENMASK(size - 1, 0);
+
+		return val == ~0UL ? size : ffz(val);
+	}
+
+	return _find_first_zero_bit(addr, size);
+}
 #else /* CONFIG_GENERIC_FIND_FIRST_BIT */
 
 #ifndef find_first_bit
@@ -126,6 +147,27 @@ extern unsigned long find_first_zero_bit(const unsigned long *addr,
 
 #endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
 
+#ifndef find_last_bit
+/**
+ * find_last_bit - find the last set bit in a memory region
+ * @addr: The address to start the search at
+ * @size: The number of bits to search
+ *
+ * Returns the bit number of the last set bit, or size.
+ */
+static inline
+unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+{
+	if (small_const_nbits(size)) {
+		unsigned long val = *addr & GENMASK(size - 1, 0);
+
+		return val ? __fls(val) : size;
+	}
+
+	return _find_last_bit(addr, size);
+}
+#endif
+
 /**
  * find_next_clump8 - find next 8-bit clump with set bits in a memory region
  * @clump: location to store copy of found clump
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index a5a48303b0f1..26bf15e6cd35 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -286,17 +286,5 @@ static __always_inline void __assign_bit(long nr, volatile unsigned long *addr,
 })
 #endif
 
-#ifndef find_last_bit
-/**
- * find_last_bit - find the last set bit in a memory region
- * @addr: The address to start the search at
- * @size: The number of bits to search
- *
- * Returns the bit number of the last set bit, or size.
- */
-extern unsigned long find_last_bit(const unsigned long *addr,
-				   unsigned long size);
-#endif
-
 #endif /* __KERNEL__ */
 #endif
diff --git a/lib/find_bit.c b/lib/find_bit.c
index b03a101367f8..0f8e2e369b1d 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -75,7 +75,7 @@ EXPORT_SYMBOL(_find_next_bit);
 /*
  * Find the first set bit in a memory region.
  */
-unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
 {
 	unsigned long idx;
 
@@ -86,14 +86,14 @@ unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
 
 	return size;
 }
-EXPORT_SYMBOL(find_first_bit);
+EXPORT_SYMBOL(_find_first_bit);
 #endif
 
 #ifndef find_first_zero_bit
 /*
  * Find the first cleared bit in a memory region.
  */
-unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
 {
 	unsigned long idx;
 
@@ -104,11 +104,11 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
 
 	return size;
 }
-EXPORT_SYMBOL(find_first_zero_bit);
+EXPORT_SYMBOL(_find_first_zero_bit);
 #endif
 
 #ifndef find_last_bit
-unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
+unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
 {
 	if (size) {
 		unsigned long val = BITMAP_LAST_WORD_MASK(size);
@@ -124,7 +124,7 @@ unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
 	}
 	return size;
 }
-EXPORT_SYMBOL(find_last_bit);
+EXPORT_SYMBOL(_find_last_bit);
 #endif
 
 unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
-- 
2.25.1


  parent reply	other threads:[~2021-03-21 21:56 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-21 21:54 [PATCH v5 00/12] lib/find_bit: fast path for small bitmaps Yury Norov
2021-03-21 21:54 ` [PATCH 01/12] tools: disable -Wno-type-limits Yury Norov
2021-03-21 21:54 ` [PATCH 02/12] tools: bitmap: sync function declarations with the kernel Yury Norov
2021-03-21 21:54 ` [PATCH 03/12] tools: sync BITMAP_LAST_WORD_MASK() macro " Yury Norov
2021-03-21 21:54 ` [PATCH 04/12] arch: rearrange headers inclusion order in asm/bitops for m68k and sh Yury Norov
2021-03-21 21:54 ` [PATCH 05/12] lib: extend the scope of small_const_nbits() macro Yury Norov
2021-03-21 21:54 ` [PATCH 06/12] tools: sync small_const_nbits() macro with the kernel Yury Norov
2021-03-22  8:34   ` Rasmus Villemoes
2021-03-24 19:49     ` Yury Norov
2021-03-21 21:54 ` [PATCH 07/12] lib: inline _find_next_bit() wrappers Yury Norov
2021-03-21 21:54 ` [PATCH 08/12] tools: sync find_next_bit implementation Yury Norov
2021-03-21 21:54 ` [PATCH 09/12] lib: add fast path for find_next_*_bit() Yury Norov
2021-03-21 21:54 ` Yury Norov [this message]
2021-03-21 21:54 ` [PATCH 11/12] tools: sync lib/find_bit implementation Yury Norov
2021-03-21 21:54 ` [PATCH 12/12] MAINTAINERS: Add entry for the bitmap API Yury Norov
2021-04-01  0:31 [PATCH v6 00/12] lib/find_bit: fast path for small bitmaps Yury Norov
2021-04-01  0:31 ` [PATCH 10/12] lib: add fast path for find_first_*_bit() and find_last_bit() Yury Norov
2021-04-01  8:58   ` Andy Shevchenko

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