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Message-Id: <20210121000630.371883-7-yury.norov@gmail.com>
Date: Wed, 20 Jan 2021 16:06:30 -0800
From: Yury Norov <yury.norov@...il.com>
To: linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
linux-sh@...r.kernel.org, linux-arch@...r.kernel.org
Cc: Yury Norov <yury.norov@...il.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>, Arnd Bergmann <arnd@...db.de>,
Dennis Zhou <dennis@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Wolfram Sang <wsa+renesas@...g-engineering.com>,
David Sterba <dsterba@...e.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Stefano Brivio <sbrivio@...hat.com>,
"Ma, Jianpeng" <jianpeng.ma@...el.com>,
Wei Yang <richard.weiyang@...ux.alibaba.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Rasmus Villemoes <rasmus.villemoes@...vas.dk>
Subject: [PATCH 6/6] lib: add fast path for find_first_*_bit() and find_last_bit()
Similarly to bitmap functions, users will 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@...il.com>
---
include/asm-generic/bitops/find.h | 56 ++++++++++++++++++++++++++++---
include/linux/bitops.h | 12 -------
lib/find_bit.c | 12 +++----
3 files changed, 58 insertions(+), 22 deletions(-)
diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index d45096069011..8708e333fc69 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
/**
@@ -111,8 +114,21 @@ 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 idx;
+
+ if (!*addr)
+ return size;
+
+ idx = __ffs(*addr);
+ return idx < size ? idx : size;
+ }
+
+ return _find_first_bit(addr, size);
+}
/**
* find_first_zero_bit - find the first cleared bit in a memory region
@@ -122,8 +138,20 @@ 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 idx;
+ if (*addr == ~0UL)
+ return size;
+
+ idx = ffz(*addr);
+ return idx < size ? idx : size;
+ }
+
+ return _find_first_zero_bit(addr, size);
+}
#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
#ifndef find_first_bit
@@ -135,6 +163,26 @@ 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 & BITMAP_LAST_WORD_MASK(size);
+ 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 a0e138bbb8ce..1d41193be4ab 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -297,17 +297,5 @@ 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
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