linux-kernel - Re: [PATCH] Input: evdev - Avoid duplicate checking of empty SYN

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Date:	Sat, 2 Jan 2016 20:31:06 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Aniroop Mathur <a.mathur@...sung.com>
Cc:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	aniroop.mathur@...il.com
Subject: Re: [PATCH] Input: evdev - Avoid duplicate checking of empty
 SYN_REPORT

Hi Aniroop,

On Thu, Dec 31, 2015 at 04:55:58AM +0530, Aniroop Mathur wrote:
> Input core already drops empty syn_report event so there is no need
> to check again for dropping empty syn_report event in evdev handler
> for all clients on every new event.

This reasoning is flawed: if all events from the packet are filtered out
for the given client we should be suppressing EV_SYN/SYN_REPORT pair as
well.

Thanks.

> 
> Signed-off-by: Aniroop Mathur <a.mathur@...sung.com>
> ---
>  drivers/input/evdev.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index e9ae3d5..6e242b7 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -276,13 +276,8 @@ static void evdev_pass_values(struct evdev_client *client,
>  		if (__evdev_is_filtered(client, v->type, v->code))
>  			continue;
>  
> -		if (v->type == EV_SYN && v->code == SYN_REPORT) {
> -			/* drop empty SYN_REPORT */
> -			if (client->packet_head == client->head)
> -				continue;
> -
> +		if (v->type == EV_SYN && v->code == SYN_REPORT)
>  			wakeup = true;
> -		}
>  
>  		event.type = v->type;
>  		event.code = v->code;
> -- 
> 2.6.2
> 

-- 
Dmitry
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