On Mon, Oct 16, 2017 at 01:51:01AM -0400, Joshua Kinard wrote: > The only uncertainty I have is the bottom of atomic_sub_if_positive and > atomic64_sub_if_positive. In R10000_LLSC_WAR case, the end of the assembler is: > > "+" GCC_OFF_SMALL_ASM() (v->counter) > : "Ir" (i), GCC_OFF_SMALL_ASM() (v->counter) The GCC_OFF_SMALL_ASM() (v->counter) input here looks redundant because 1) the output one has +, which means input and output 2) %4 is never referenced. > : "memory"); To me this appears to be redundant since the only side effects are writing to v->counter which is already an output, and in any case the smp_mb__before_llsc() and smp_llsc_mb() imply memory clobber anyway. > > While the standard case is: > > : "=&r" (result), "=&r" (temp), > "+" GCC_OFF_SMALL_ASM() (v->counter) > : "Ir" (i)); So yeh, I'd go for this unless anybody can think of a reason it wouldn't work in the R10000_LLSC_WAR case. Hope that helps. Cheers James
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