On Fri, 2016-03-06 at 03:49:48 UTC, Boqun Feng wrote:
> diff --git a/arch/powerpc/include/asm/spinlock.h
> b/arch/powerpc/include/asm/spinlock.h
> index 523673d7583c..2ed893662866 100644
> --- a/arch/powerpc/include/asm/spinlock.h
> +++ b/arch/powerpc/include/asm/spinlock.h
> @@ -64,6 +64,25 @@ static inline int arch_spin_is_locked(arch_spinlock_t
> *lock)
> }
>
> /*
> + * Use a ll/sc loop to read the lock value, the STORE part of this operation
> is
> + * used for making later lock operation observe it.
> + */
> +static inline bool arch_spin_is_locked_sync(arch_spinlock_t *lock)
> +{
> + arch_spinlock_t tmp;
> +
> + __asm__ __volatile__(
> +"1: " PPC_LWARX(%0, 0, %2, 1) "\n"
As discussed offline I think we want to use EH=0 here (the final parameter).
From the ISA:
The value of EH provides a hint as to whether the program will perform a
subsequent store to the word in storage addressed by EA before some other
processor attempts to modify it.
0 Other programs might attempt to modify the word in storage addressed by EA
regardless of the result of the corresponding stwcx. instruction.
cheers
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