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From:   Nicholas Piggin <npiggin@gmail.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Nicholas Piggin <npiggin@gmail.com>, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, Vineet Gupta <vgupta@kernel.org>,
        linux-snps-arc@lists.infradead.org, Brian Cain <bcain@quicinc.com>,
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        loongarch@lists.linux.dev,
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        linux-m68k@lists.linux-m68k.org, Michal Simek <monstr@monstr.eu>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
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        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Stafford Horne <shorne@gmail.com>,
        linux-openrisc@vger.kernel.org,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv@lists.infradead.org,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>,
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        Johannes Berg <johannes@sipsolutions.net>,
        linux-um@lists.infradead.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>,
        Kevin Hilman <khilman@baylibre.com>,
        Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH] Remove HAVE_VIRT_CPU_ACCOUNTING_GEN option
Date:   Sat, 29 Apr 2023 16:33:48 +1000
Message-Id: <20230429063348.125544-1-npiggin@gmail.com>
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This option was created in commit 554b0004d0ec4 ("vtime: Add
HAVE_VIRT_CPU_ACCOUNTING_GEN Kconfig") for architectures to indicate
they support the 64-bit cputime_t required for VIRT_CPU_ACCOUNTING_GEN.

The cputime_t type has since been removed, so this doesn't have any
meaning. Remove it.

Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: linux-snps-arc@lists.infradead.org
Cc: Brian Cain <bcain@quicinc.com>
Cc: linux-hexagon@vger.kernel.org
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: loongarch@lists.linux.dev
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-m68k@lists.linux-m68k.org
Cc: Michal Simek <monstr@monstr.eu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Stafford Horne <shorne@gmail.com>
Cc: linux-openrisc@vger.kernel.org
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-riscv@lists.infradead.org
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: linux-sh@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-um@lists.infradead.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Hi,

Could we tidy this? I don't know what tree it can go in, timers,
sched, asm-generic, probably doesn't matter.

The only thing this actually does is gate VIRT_CPU_ACCOUNTING_GEN and
NO_HZ_FULL so if your arch has some other issue that requires this
then the documentation needs to change. Any concerns from the archs?
I.e., 32-bit that does *not* define HAVE_VIRT_CPU_ACCOUNTING_GEN
which looks to be:

arc
hexagon
loongarch 32-bit with SMP
m68k
microblaze
mips 32-bit with SMP
nios2
openrisc
parisc 32-bit
riscv 32-bit
sh
sparc 32-bit
um 32-bit
x86 32-bit

Thanks,
Nick
--
 arch/Kconfig           | 11 -----------
 arch/arm/Kconfig       |  1 -
 arch/csky/Kconfig      |  1 -
 arch/loongarch/Kconfig |  1 -
 arch/mips/Kconfig      |  1 -
 arch/powerpc/Kconfig   |  1 -
 arch/xtensa/Kconfig    |  1 -
 init/Kconfig           |  1 -
 kernel/time/Kconfig    |  2 --
 9 files changed, 20 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 205fd23e0cad..b77b41d25e40 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -869,17 +869,6 @@ config HAVE_VIRT_CPU_ACCOUNTING_IDLE
 config ARCH_HAS_SCALED_CPUTIME
 	bool
 
-config HAVE_VIRT_CPU_ACCOUNTING_GEN
-	bool
-	default y if 64BIT
-	help
-	  With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
-	  Before enabling this option, arch code must be audited
-	  to ensure there are no races in concurrent read/write of
-	  cputime_t. For example, reading/writing 64-bit cputime_t on
-	  some 32-bit arches may require multiple accesses, so proper
-	  locking is needed to protect against concurrent accesses.
-
 config HAVE_IRQ_TIME_ACCOUNTING
 	bool
 	help
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0fb4b218f665..9c05f25db4e4 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -123,7 +123,6 @@ config ARM
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_UID16
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select IRQ_FORCED_THREADING
 	select MODULES_USE_ELF_REL
 	select NEED_DMA_MAP_STATE
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 00379a843c37..dd1decc2a22d 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -73,7 +73,6 @@ config CSKY
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_CONTEXT_TRACKING_USER
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DYNAMIC_FTRACE
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index f44f6ea54e46..7dc71c89bfae 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -122,7 +122,6 @@ config LOONGARCH
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_TIF_NOHZ
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
 	select IRQ_FORCED_THREADING
 	select IRQ_LOONGARCH_CPU
 	select MMU_GATHER_MERGE_VMAS if MMU
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index c2f5498d207f..d84cb8bbee53 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -87,7 +87,6 @@ config MIPS
 	select HAVE_SPARSE_SYSCALL_NR
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN if 64BIT || !SMP
 	select IRQ_FORCED_THREADING
 	select ISA if EISA
 	select MODULES_USE_ELF_REL if MODULES
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index acffffbd5d77..185195f349d9 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -271,7 +271,6 @@ config PPC
 	select HAVE_STATIC_CALL			if PPC32
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_VIRT_CPU_ACCOUNTING
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select HUGETLB_PAGE_SIZE_VARIABLE	if PPC_BOOK3S_64 && HUGETLB_PAGE
 	select IOMMU_HELPER			if PPC64
 	select IRQ_DOMAIN
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 3c6e5471f025..04f1399d9ce8 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -47,7 +47,6 @@ config XTENSA
 	select HAVE_PERF_EVENTS
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
-	select HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select PERF_USE_VMALLOC
diff --git a/init/Kconfig b/init/Kconfig
index 32c24950c4ce..835fb5e78a8f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -504,7 +504,6 @@ config VIRT_CPU_ACCOUNTING_NATIVE
 config VIRT_CPU_ACCOUNTING_GEN
 	bool "Full dynticks CPU time accounting"
 	depends on HAVE_CONTEXT_TRACKING_USER
-	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	depends on GENERIC_CLOCKEVENTS
 	select VIRT_CPU_ACCOUNTING
 	select CONTEXT_TRACKING_USER
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index bae8f11070be..d4325dae1f03 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -121,8 +121,6 @@ config NO_HZ_FULL
 	# We need at least one periodic CPU for timekeeping
 	depends on SMP
 	depends on HAVE_CONTEXT_TRACKING_USER
-	# VIRT_CPU_ACCOUNTING_GEN dependency
-	depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
 	select NO_HZ_COMMON
 	select RCU_NOCB_CPU
 	select VIRT_CPU_ACCOUNTING_GEN
-- 
2.40.1