| Date | Wed, 22 Feb 2017 12:37:09 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 10/25] openrisc: add spinlock implementation |
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On Wed, Feb 22, 2017 at 04:11:39AM +0900, Stafford Horne wrote:
> +static inline int arch_spin_trylock(arch_spinlock_t *lock) > +{ > + unsigned long contended, tmp; > + u32 slock; > + > + /* contended = (lock->tickets.owner != lock->tickets.next) */ > + __asm__ __volatile__( > + "1: l.lwa %0, 0(%3) \n" > + " l.srli %1, %0, 16 \n" > + " l.andi %2, %0, 0xffff \n" > + " l.sfeq %1, %2 \n" > + " l.bnf 1f \n" > + " l.ori %1, r0, 1 \n" > + " l.add %0, %0, %4 \n" > + " l.swa 0(%3), %0 \n" > + " l.bnf 1b \n" > + " l.ori %1, r0, 0 \n"
#ifdef CONFIG_SMP " l.sync \n" #endif
> + "1: \n" > + : "=&r" (slock), "=&r" (contended), "=&r" (tmp) > + : "r" (&lock->slock), "r" (1 << TICKET_SHIFT) > + : "cc", "memory"); > +
Then s/contended/acquired/, flip the bitset in the asm, and replace the entire thing below with:
return acquired;
> + if (!contended) { > + smp_mb(); > + return 1; > + } else { > + return 0; > + } > +}
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