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    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@infradead.org>
    AuthorDate: Fri, 6 Jun 2014 19:53:16 +0200
    Committer: Ingo Molnar <mingo@kernel.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@infradead.org>
    Reported-by: Mikulas Patocka <mpatocka@redhat.com>
    Cc: David Miller <davem@davemloft.net>
    Cc: Chris Metcalf <cmetcalf@tilera.com>
    Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
    Cc: Vineet Gupta <vgupta@synopsys.com>
    Cc: Jason Low <jason.low2@hp.com>
    Cc: Waiman Long <waiman.long@hp.com>
    Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
    Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
    Cc: John David Anglin <dave.anglin@bell.net>
    Cc: James Hogan <james.hogan@imgtec.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Davidlohr Bueso <davidlohr@hp.com>
    Cc: stable@vger.kernel.org
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-kernel@vger.kernel.org
    Cc: linuxppc-dev@lists.ozlabs.org
    Cc: sparclinux@vger.kernel.org
    Link: http://lkml.kernel.org/r/20140606175316.GV13930@laptop.programming.kicks-ass.net
    Signed-off-by: Ingo Molnar <mingo@kernel.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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