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    Subject[tip:x86/asm] x86/spinlocks: Eliminate TICKET_MASK
    Commit-ID:  7931d493051ea9b09e4fddee2dc40b2eb88d62b9
    Gitweb: http://git.kernel.org/tip/7931d493051ea9b09e4fddee2dc40b2eb88d62b9
    Author: Jan Beulich <JBeulich@suse.com>
    AuthorDate: Fri, 3 Feb 2012 15:06:26 +0000
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Tue, 7 Feb 2012 10:09:54 +0100

    x86/spinlocks: Eliminate TICKET_MASK

    The definition of it being questionable already (unnecessarily
    including a cast), and it being used in a single place that can
    be written shorter without it, remove this #define.

    Along the same lines, simplify __ticket_spin_is_locked()'s main
    expression, which was the more convoluted way because of needs
    that went away with the recent type changes by Jeremy.

    This is pure cleanup, no functional change intended.

    Signed-off-by: Jan Beulich <jbeulich@suse.com>
    Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/4F2C06020200007800071066@nat28.tlf.novell.com
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/include/asm/spinlock.h | 4 ++--
    arch/x86/include/asm/spinlock_types.h | 1 -
    2 files changed, 2 insertions(+), 3 deletions(-)

    diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
    index a82c2bf..76bfa2c 100644
    --- a/arch/x86/include/asm/spinlock.h
    +++ b/arch/x86/include/asm/spinlock.h
    @@ -88,14 +88,14 @@ static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
    {
    struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);

    - return !!(tmp.tail ^ tmp.head);
    + return tmp.tail != tmp.head;
    }

    static inline int __ticket_spin_is_contended(arch_spinlock_t *lock)
    {
    struct __raw_tickets tmp = ACCESS_ONCE(lock->tickets);

    - return ((tmp.tail - tmp.head) & TICKET_MASK) > 1;
    + return (__ticket_t)(tmp.tail - tmp.head) > 1;
    }

    #ifndef CONFIG_PARAVIRT_SPINLOCKS
    diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
    index 8ebd5df..ad0ad07 100644
    --- a/arch/x86/include/asm/spinlock_types.h
    +++ b/arch/x86/include/asm/spinlock_types.h
    @@ -16,7 +16,6 @@ typedef u32 __ticketpair_t;
    #endif

    #define TICKET_SHIFT (sizeof(__ticket_t) * 8)
    -#define TICKET_MASK ((__ticket_t)((1 << TICKET_SHIFT) - 1))

    typedef struct arch_spinlock {
    union {

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