Re: [v2] powerpc: spinlock: Fix spin_unlock_wait()
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-06-06 11:14:28
Also in:
lkml
On Fri, 2016-03-06 at 03:49:48 UTC, Boqun Feng wrote:
quoted hunk ↗ jump to hunk
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