[PATCH 04/16] arch: remove GENERIC_FIND_FIRST_BIT entirely

Yury Norov
2021-10-01T18:13:31Z

In 5.12 cycle we enabled GENERIC_FIND_FIRST_BIT config option for ARM64
and MIPS. It increased performance and shrunk .text size; and so far
I didn't receive any negative feedback on the change.

https://lore.kernel.org/linux-arch/20210225135700.1381396-1-yury.norov@gmail.com/

Now I think it's a good time to switch all architectures to use
find_{first,last}_bit() unconditionally, and so remove corresponding
config option.

The patch does't introduce functioal changes for arc, arm, arm64, mips,
m68k, s390 and x86, for other architectures I expect improvement both in
performance and .text size.

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Tested-by: Alexander Lobakin <alobakin@pm.me> (mips)
Reviewed-by: Alexander Lobakin <alobakin@pm.me> (mips)
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
arch/arc/Kconfig | 1 -
arch/arm64/Kconfig | 1 -
arch/mips/Kconfig | 1 -
arch/s390/Kconfig | 1 -
arch/x86/Kconfig | 1 -
arch/x86/um/Kconfig | 1 -
include/linux/find.h | 13 -------------
lib/Kconfig | 3 ---
8 files changed, 22 deletions(-)

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 3a5a80f302e1..248389278e8f 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -20,7 +20,6 @@ config ARC
select COMMON_CLK
select DMA_DIRECT_REMAP
select GENERIC_ATOMIC64 if !ISA_ARCV2 || !(ARC_HAS_LL64 && ARC_HAS_LLSC)
- select GENERIC_FIND_FIRST_BIT
# for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
select GENERIC_IRQ_SHOW
select GENERIC_PCI_IOMAP
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5c7ae4c3954b..abbd7b1e549f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -119,7 +119,6 @@ config ARM64
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
- select GENERIC_FIND_FIRST_BIT
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IRQ_IPI
select GENERIC_IRQ_PROBE
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 771ca53af06d..0cf31a6cbee1 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -32,7 +32,6 @@ config MIPS
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CMOS_UPDATE
select GENERIC_CPU_AUTOPROBE
- select GENERIC_FIND_FIRST_BIT
select GENERIC_GETTIMEOFDAY
select GENERIC_IOMAP
select GENERIC_IRQ_PROBE
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b86de61b8caa..b0bb3aaec5f2 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -127,7 +127,6 @@ config S390
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES
select GENERIC_ENTRY
- select GENERIC_FIND_FIRST_BIT
select GENERIC_GETTIMEOFDAY
select GENERIC_PTDUMP
select GENERIC_SMP_IDLE_THREAD
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 16e216b57863..8889bfa5597e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -134,7 +134,6 @@ config X86
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
select GENERIC_ENTRY
- select GENERIC_FIND_FIRST_BIT
select GENERIC_IOMAP
select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
index 95d26a69088b..40d6a06e41c8 100644
--- a/arch/x86/um/Kconfig
+++ b/arch/x86/um/Kconfig
@@ -8,7 +8,6 @@ endmenu

config UML_X86
def_bool y
- select GENERIC_FIND_FIRST_BIT

config 64BIT
bool "64-bit kernel" if "$(SUBARCH)" = "x86"
diff --git a/include/linux/find.h b/include/linux/find.h
index c5410c243e04..ea57f7f38c49 100644
--- a/include/linux/find.h
+++ b/include/linux/find.h
@@ -101,8 +101,6 @@ unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
}
#endif

-#ifdef CONFIG_GENERIC_FIND_FIRST_BIT
-
#ifndef find_first_bit
/**
* find_first_bit - find the first set bit in a memory region
@@ -147,17 +145,6 @@ unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
}
#endif

-#else /* CONFIG_GENERIC_FIND_FIRST_BIT */
-
-#ifndef find_first_bit
-#define find_first_bit(addr, size) find_next_bit((addr), (size), 0)
-#endif
-#ifndef find_first_zero_bit
-#define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0)
-#endif
-
-#endif /* CONFIG_GENERIC_FIND_FIRST_BIT */
-
#ifndef find_last_bit
/**
* find_last_bit - find the last set bit in a memory region
diff --git a/lib/Kconfig b/lib/Kconfig
index 5e7165e6a346..6a6ae5312fa0 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -65,9 +65,6 @@ config GENERIC_STRNLEN_USER
config GENERIC_NET_UTILS
bool

-config GENERIC_FIND_FIRST_BIT
- bool
-
source "lib/math/Kconfig"

config NO_GENERIC_PCI_IOPORT_MAP
--
2.30.2