linux-kernel - [PATCH 01/33] locking/atomic: make ARCH

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Date:   Mon, 10 May 2021 10:37:21 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org, will@...nel.org,
        boqun.feng@...il.com, peterz@...radead.org
Cc:     aou@...s.berkeley.edu, arnd@...db.de, bcain@...eaurora.org,
        benh@...nel.crashing.org, chris@...kel.net, dalias@...c.org,
        davem@...emloft.net, deanbo422@...il.com, deller@....de,
        geert@...ux-m68k.org, green.hu@...il.com, guoren@...nel.org,
        ink@...assic.park.msu.ru, James.Bottomley@...senPartnership.com,
        jcmvbkbc@...il.com, jonas@...thpole.se, ley.foon.tan@...el.com,
        linux@...linux.org.uk, mark.rutland@....com, mattst88@...il.com,
        monstr@...str.eu, mpe@...erman.id.au, nickhu@...estech.com,
        palmer@...belt.com, paulus@...ba.org, paul.walmsley@...ive.com,
        rth@...ddle.net, shorne@...il.com,
        stefan.kristiansson@...nalahti.fi, tsbogend@...ha.franken.de,
        vgupta@...opsys.com, ysato@...rs.sourceforge.jp
Subject: [PATCH 01/33] locking/atomic: make ARCH_ATOMIC a Kconfig symbol

Subsequent patches will move architectures over to the ARCH_ATOMIC API,
after preparing the asm-generic atomic implementations to function with
or without ARCH_ATOMIC.

As some architectures use the asm-generic implementations exclusively
(and don't have a local atomic.h), and to avoid the risk that
ARCH_ATOMIC isn't defined in some cases we expect, let's make the
ARCH_ATOMIC macro a Kconfig symbol instead, so that we can guarantee it
is consistently available where needed.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will@...nel.org>
---
 arch/Kconfig                    | 3 +++
 arch/arm64/Kconfig              | 1 +
 arch/arm64/include/asm/atomic.h | 2 --
 arch/s390/Kconfig               | 1 +
 arch/s390/include/asm/atomic.h  | 2 --
 arch/um/Kconfig                 | 1 +
 arch/x86/Kconfig                | 1 +
 arch/x86/include/asm/atomic.h   | 2 --
 include/linux/atomic.h          | 2 +-
 9 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index c45b770d3579..3fb3b12d4a95 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -11,6 +11,9 @@ source "arch/$(SRCARCH)/Kconfig"
 
 menu "General architecture-dependent options"
 
+config ARCH_ATOMIC
+	bool
+
 config CRASH_CORE
 	bool
 
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9f1d8566bbf9..62ab429d1f42 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -9,6 +9,7 @@ config ARM64
 	select ACPI_MCFG if (ACPI && PCI)
 	select ACPI_SPCR_TABLE if ACPI
 	select ACPI_PPTT if ACPI
+	select ARCH_ATOMIC
 	select ARCH_HAS_DEBUG_WX
 	select ARCH_BINFMT_ELF_STATE
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
diff --git a/arch/arm64/include/asm/atomic.h b/arch/arm64/include/asm/atomic.h
index b56a4b2bc248..c9979273d389 100644
--- a/arch/arm64/include/asm/atomic.h
+++ b/arch/arm64/include/asm/atomic.h
@@ -223,6 +223,4 @@ static __always_inline long arch_atomic64_dec_if_positive(atomic64_t *v)
 
 #define arch_atomic64_dec_if_positive		arch_atomic64_dec_if_positive
 
-#define ARCH_ATOMIC
-
 #endif /* __ASM_ATOMIC_H */
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b4c7c34069f8..85374a36c69e 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -58,6 +58,7 @@ config S390
 	# Note: keep this list sorted alphabetically
 	#
 	imply IMA_SECURE_AND_OR_TRUSTED_BOOT
+	select ARCH_ATOMIC
 	select ARCH_32BIT_USTAT_F_TINODE
 	select ARCH_BINFMT_ELF_STATE
 	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM
diff --git a/arch/s390/include/asm/atomic.h b/arch/s390/include/asm/atomic.h
index 7c93c6573524..7138d189cc42 100644
--- a/arch/s390/include/asm/atomic.h
+++ b/arch/s390/include/asm/atomic.h
@@ -147,6 +147,4 @@ ATOMIC64_OPS(xor)
 #define arch_atomic64_fetch_sub(_i, _v)  arch_atomic64_fetch_add(-(s64)(_i), _v)
 #define arch_atomic64_sub(_i, _v)	 arch_atomic64_add(-(s64)(_i), _v)
 
-#define ARCH_ATOMIC
-
 #endif /* __ARCH_S390_ATOMIC__  */
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 57cfd9a1c082..4370a9521ea4 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -5,6 +5,7 @@ menu "UML-specific options"
 config UML
 	bool
 	default y
+	select ARCH_ATOMIC
 	select ARCH_EPHEMERAL_INODES
 	select ARCH_HAS_KCOV
 	select ARCH_NO_PREEMPT
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0045e1b44190..11a27563033d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -58,6 +58,7 @@ config X86
 	#
 	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
+	select ARCH_ATOMIC
 	select ARCH_32BIT_OFF_T			if X86_32
 	select ARCH_CLOCKSOURCE_INIT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index f732741ad7c7..5e754e895767 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -269,6 +269,4 @@ static __always_inline int arch_atomic_fetch_xor(int i, atomic_t *v)
 # include <asm/atomic64_64.h>
 #endif
 
-#define ARCH_ATOMIC
-
 #endif /* _ASM_X86_ATOMIC_H */
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 571a11008ab5..4f8d83f9e480 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -77,7 +77,7 @@
 	__ret;								\
 })
 
-#ifdef ARCH_ATOMIC
+#ifdef CONFIG_ARCH_ATOMIC
 #include <linux/atomic-arch-fallback.h>
 #include <asm-generic/atomic-instrumented.h>
 #else
-- 
2.11.0