linux-kernel - Re: [PATCH v2 2/2] platform/chrome: cros_ec_ishtp: free ishtp buffer before sending event

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Date:   Tue, 14 Apr 2020 18:25:09 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Mathew King <mathewk@...omium.org>, linux-kernel@...r.kernel.org
Cc:     Jett Rink <jettrink@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Rushikesh S Kadam <rushikesh.s.kadam@...el.com>
Subject: Re: [PATCH v2 2/2] platform/chrome: cros_ec_ishtp: free ishtp buffer
 before sending event

Hi Jett and Mathew,

Thank you for the patch.

On 10/4/20 18:23, Mathew King wrote:
> From: Jett Rink <jettrink@...omium.org>
> 
> Recycle the ISH buffer before notifying of a response or an event. Often
> a new message is sent in response to an event and in high traffic
> scenarios this can lead to exhausting all available buffers. We can
> ensure we are using the fewest buffers possible by freeing buffers as
> soon as they are used.
> 
> Signed-off-by: Jett Rink <jettrink@...omium.org>
> Signed-off-by: Mathew King <mathewk@...omium.org>

Queued for 5.8

> ---
> v2: Reword the commit message
> ---
>  drivers/platform/chrome/cros_ec_ishtp.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_ishtp.c b/drivers/platform/chrome/cros_ec_ishtp.c
> index e673a7f738fc..ed794a7ddba9 100644
> --- a/drivers/platform/chrome/cros_ec_ishtp.c
> +++ b/drivers/platform/chrome/cros_ec_ishtp.c
> @@ -303,6 +303,10 @@ static void process_recv(struct ishtp_cl *cros_ish_cl,
>  		       rb_in_proc->buffer.data, data_len);
>  
>  error_wake_up:
> +		/* Free the buffer since we copied data or didn't need it */
> +		ishtp_cl_io_rb_recycle(rb_in_proc);
> +		rb_in_proc = NULL;
> +
>  		/* Set flag before waking up the caller */
>  		client_data->response.received = true;
>  
> @@ -312,12 +316,14 @@ static void process_recv(struct ishtp_cl *cros_ish_cl,
>  		break;
>  
>  	case CROS_MKBP_EVENT:
> +		/* Free the buffer. This is just an event without data */
> +		ishtp_cl_io_rb_recycle(rb_in_proc);
> +		rb_in_proc = NULL;
>  		/*
>  		 * Set timestamp from beginning of function since we actually
>  		 * got an incoming MKBP event
>  		 */
>  		client_data->ec_dev->last_event_time = timestamp;
> -		/* The event system doesn't send any data in buffer */
>  		schedule_work(&client_data->work_ec_evt);
>  
>  		break;
> @@ -327,8 +333,9 @@ static void process_recv(struct ishtp_cl *cros_ish_cl,
>  	}
>  
>  end_error:
> -	/* Free the buffer */
> -	ishtp_cl_io_rb_recycle(rb_in_proc);
> +	/* Free the buffer if we already haven't */
> +	if (rb_in_proc)
> +		ishtp_cl_io_rb_recycle(rb_in_proc);
>  
>  	up_read(&init_lock);
>  }
>