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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
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Date: Mon, 26 Sep 2016 09:25:36 +0100
Message-ID: <874m53gj9b.fsf@linaro.org>
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Subject: Re: [Qemu-devel] [PATCH 12/16] cpus-common: remove redundant call
 to exclusive_idle()
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, cota@braap.org, sergey.fedorov@linaro.org, serge.fdrv@gmail.com


Paolo Bonzini <pbonzini@redhat.com> writes:

> No need to call exclusive_idle() from cpu_exec_end since it is done
> immediately afterwards in cpu_exec_start.  Any exclusive section could
> run as soon as cpu_exec_end leaves, because cpu->running is false and the
> mutex is not taken, so the call does not add any protection either.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
>  cpus-common.c              | 1 -
>  docs/tcg-exclusive.promela | 1 -
>  2 files changed, 2 deletions(-)
>
> diff --git a/cpus-common.c b/cpus-common.c
> index 115f3d4..80aaf9b 100644
> --- a/cpus-common.c
> +++ b/cpus-common.c
> @@ -221,7 +221,6 @@ void cpu_exec_end(CPUState *cpu)
>              qemu_cond_signal(&exclusive_cond);
>          }
>      }
> -    exclusive_idle();
>      qemu_mutex_unlock(&qemu_cpu_list_lock);
>  }
>
> diff --git a/docs/tcg-exclusive.promela b/docs/tcg-exclusive.promela
> index 360edcd..9e7d9e3 100644
> --- a/docs/tcg-exclusive.promela
> +++ b/docs/tcg-exclusive.promela
> @@ -123,7 +123,6 @@ byte has_waiter[N_CPUS];
>          }                                                                    \
>          :: else -> skip;                                                     \
>      fi;                                                                      \
> -    exclusive_idle();                                                        \
>      MUTEX_UNLOCK(mutex);
>
>  // Promela processes


--
Alex Bennée