linux-kernel - Re: [PATCH 03/37] binder: Use wake up hint for synchronous transactions.

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Date:   Mon, 3 Jul 2017 11:18:35 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Todd Kjos <tkjos@...roid.com>
Cc:     arve@...roid.com, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org, maco@...gle.com, tkjos@...gle.com,
        Riley Andrews <riandrews@...gle.com>,
        Omprakash Dhyade <odhyade@...eaurora.org>
Subject: Re: [PATCH 03/37] binder: Use wake up hint for synchronous
 transactions.

On Thu, Jun 29, 2017 at 12:01:37PM -0700, Todd Kjos wrote:
> From: Riley Andrews <riandrews@...gle.com>
> 
> Use wake_up_interruptible_sync() to hint to the scheduler binder
> transactions are synchronous wakeups. Disable preemption while waking
> to avoid ping-ponging on the binder lock.
> 
> Signed-off-by: Todd Kjos <tkjos@...gle.com>
> Signed-off-by: Omprakash Dhyade <odhyade@...eaurora.org>

No signed-off-by from Riley?  Why not?  (just curious, not a requirement
here, but generally good practice.)

> ---
>  drivers/android/binder.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 9393924ae8e8..f7665c31feca 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -2200,8 +2200,12 @@ static void binder_transaction(struct binder_proc *proc,
>  	list_add_tail(&t->work.entry, target_list);
>  	tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
>  	list_add_tail(&tcomplete->entry, &thread->todo);
> -	if (target_wait)
> -		wake_up_interruptible(target_wait);
> +	if (target_wait) {
> +		if (reply || !(t->flags & TF_ONE_WAY))
> +			wake_up_interruptible_sync(target_wait);
> +		else
> +			wake_up_interruptible(target_wait);
> +	}

This too should be backported, right?

thanks,

greg k-h