Re: [Qemu-devel] [PATCH v7 2/6] Wrapper function to wait on condition for the main loop mutex

[David Gibson]

On Fri, Mar 22, 2019 at 12:03:49PM +0530, Aravinda Prasad wrote:
> Introduce a wrapper function to wait on condition for
> the main loop mutex. This function atomically releases
> the main loop mutex and causes the calling thread to
> block on the condition.
> 
> Signed-off-by: Aravinda Prasad <address@hidden>

I don't see much value to this.  It's not really more expressive, and
is barely shorted than just open coding
        qemu_cond_wait(cond, &qemu_global_mutex)
wherever you need it.


> ---
>  cpus.c                   |    5 +++++
>  include/qemu/main-loop.h |    8 ++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/cpus.c b/cpus.c
> index e83f72b..d9379e7 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1858,6 +1858,11 @@ void qemu_mutex_unlock_iothread(void)
>      qemu_mutex_unlock(&qemu_global_mutex);
>  }
>  
> +void qemu_cond_wait_iothread(QemuCond *cond)
> +{
> +    qemu_cond_wait(cond, &qemu_global_mutex);
> +}
> +
>  static bool all_vcpus_paused(void)
>  {
>      CPUState *cpu;
> diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
> index f6ba78e..a6d20b0 100644
> --- a/include/qemu/main-loop.h
> +++ b/include/qemu/main-loop.h
> @@ -295,6 +295,14 @@ void qemu_mutex_lock_iothread_impl(const char *file, int 
> line);
>   */
>  void qemu_mutex_unlock_iothread(void);
>  
> +/*
> + * qemu_cond_wait_iothread: Wait on condition for the main loop mutex
> + *
> + * This function atomically releases the main loop mutex and causes
> + * the calling thread to block on the condition.
> + */
> +void qemu_cond_wait_iothread(QemuCond *cond);
> +
>  /* internal interfaces */
>  
>  void qemu_fd_register(int fd);
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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