Re: [Qemu-devel] [PATCH v2 08/12] cpus: always call seqlock_write in cpu_update_icount

[Richard Henderson]

On 09/10/2018 04:27 PM, Emilio G. Cota wrote:
>  
> -#ifndef CONFIG_ATOMIC64
>      seqlock_write_lock(&timers_state.vm_clock_seqlock,
>                         &timers_state.vm_clock_lock);
> -#endif
>      atomic_set__nocheck(&timers_state.qemu_icount,
>                          timers_state.qemu_icount + executed);
> -#ifndef CONFIG_ATOMIC64
>      seqlock_write_unlock(&timers_state.vm_clock_seqlock,
>                           &timers_state.vm_clock_lock);
> -#endif

I don't understand this.  Surely you either want atomic64_set,
or an actual atomic64_add, but no extra lock when CONFIG_ATOMIC64.


r~