linux-kernel - [tip:locking/urgent] locking/mutex: Disable optimistic spinning on some architectures

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Message-ID: <tip-4badad352a6bb202ec68afa7a574c0bb961e5ebc@git.kernel.org>
Date:	Wed, 16 Jul 2014 12:24:31 -0700
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, catalin.marinas@....com,
	torvalds@...ux-foundation.org, peterz@...radead.org,
	cmetcalf@...era.com, jason.low2@...com, linux@....linux.org.uk,
	tglx@...utronix.de, davidlohr@...com, linux-kernel@...r.kernel.org,
	hpa@...or.com, dave.anglin@...l.net,
	James.Bottomley@...senpartnership.com, will.deacon@....com,
	waiman.long@...com, james.hogan@...tec.com, mpatocka@...hat.com,
	davem@...emloft.net, paulmck@...ux.vnet.ibm.com,
	benh@...nel.crashing.org, vgupta@...opsys.com,
	jejb@...isc-linux.org
Subject: [tip:locking/urgent] locking/mutex:
  Disable optimistic spinning on some architectures

Commit-ID:  4badad352a6bb202ec68afa7a574c0bb961e5ebc
Gitweb:     http://git.kernel.org/tip/4badad352a6bb202ec68afa7a574c0bb961e5ebc
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Fri, 6 Jun 2014 19:53:16 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 16 Jul 2014 14:57:07 +0200

locking/mutex: Disable optimistic spinning on some architectures

The optimistic spin code assumes regular stores and cmpxchg() play nice;
this is found to not be true for at least: parisc, sparc32, tile32,
metag-lock1, arc-!llsc and hexagon.

There is further wreckage, but this in particular seemed easy to
trigger, so blacklist this.

Opt in for known good archs.

Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Reported-by: Mikulas Patocka <mpatocka@...hat.com>
Cc: David Miller <davem@...emloft.net>
Cc: Chris Metcalf <cmetcalf@...era.com>
Cc: James Bottomley <James.Bottomley@...senpartnership.com>
Cc: Vineet Gupta <vgupta@...opsys.com>
Cc: Jason Low <jason.low2@...com>
Cc: Waiman Long <waiman.long@...com>
Cc: "James E.J. Bottomley" <jejb@...isc-linux.org>
Cc: Paul McKenney <paulmck@...ux.vnet.ibm.com>
Cc: John David Anglin <dave.anglin@...l.net>
Cc: James Hogan <james.hogan@...tec.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Davidlohr Bueso <davidlohr@...com>
Cc: stable@...r.kernel.org
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Russell King <linux@....linux.org.uk>
Cc: Will Deacon <will.deacon@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: sparclinux@...r.kernel.org
Link: http://lkml.kernel.org/r/20140606175316.GV13930@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/arm/Kconfig     | 1 +
 arch/arm64/Kconfig   | 1 +
 arch/powerpc/Kconfig | 1 +
 arch/sparc/Kconfig   | 1 +
 arch/x86/Kconfig     | 1 +
 kernel/Kconfig.locks | 5 ++++-
 6 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 245058b..88acf8b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -6,6 +6,7 @@ config ARM
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_MIGHT_HAVE_PC_PARPORT
+	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_WANT_IPC_PARSE_VERSION
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a474de34..839f48c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -4,6 +4,7 @@ config ARM64
 	select ARCH_HAS_OPP
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_USE_CMPXCHG_LOCKREF
+	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 	select ARCH_WANT_FRAME_POINTERS
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index fefe7c8..80b94b0 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -145,6 +145,7 @@ config PPC
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select ARCH_USE_CMPXCHG_LOCKREF if PPC64
 	select HAVE_ARCH_AUDITSYSCALL
+	select ARCH_SUPPORTS_ATOMIC_RMW
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 29f2e98..407c87d 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -78,6 +78,7 @@ config SPARC64
 	select HAVE_C_RECORDMCOUNT
 	select NO_BOOTMEM
 	select HAVE_ARCH_AUDITSYSCALL
+	select ARCH_SUPPORTS_ATOMIC_RMW
 
 config ARCH_DEFCONFIG
 	string
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8f749e..d24887b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -131,6 +131,7 @@ config X86
 	select HAVE_CC_STACKPROTECTOR
 	select GENERIC_CPU_AUTOPROBE
 	select HAVE_ARCH_AUDITSYSCALL
+	select ARCH_SUPPORTS_ATOMIC_RMW
 
 config INSTRUCTION_DECODER
 	def_bool y
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index 35536d9..8190794 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -220,9 +220,12 @@ config INLINE_WRITE_UNLOCK_IRQRESTORE
 
 endif
 
+config ARCH_SUPPORTS_ATOMIC_RMW
+	bool
+
 config MUTEX_SPIN_ON_OWNER
 	def_bool y
-	depends on SMP && !DEBUG_MUTEXES
+	depends on SMP && !DEBUG_MUTEXES && ARCH_SUPPORTS_ATOMIC_RMW
 
 config ARCH_USE_QUEUE_RWLOCK
 	bool
--
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