linux-kernel - Re: [PATCH] drm/hyperv: Add ratelimit on error message

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Date:   Sat, 10 Sep 2022 20:06:05 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Saurabh Sengar <ssengar@...ux.microsoft.com>,
        ssengar@...rosoft.com, drawat.floss@...il.com, airlied@...ux.ie,
        daniel@...ll.ch, linux-hyperv@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        mikelley@...rosoft.com
Subject: Re: [PATCH] drm/hyperv: Add ratelimit on error message

Hi

Am 09.09.22 um 17:09 schrieb Saurabh Sengar:
> Due to a full ring buffer, the driver may be unable to send updates to
> the Hyper-V host.  But outputing the error message can make the problem
> worse because console output is also typically written to the frame
> buffer.
> Rate limiting the error message, also output the error code for additional
> diagnosability.
> 
> Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
> ---
>   drivers/gpu/drm/hyperv/hyperv_drm_proto.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> index 76a182a..013a782 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> @@ -208,7 +208,7 @@ static inline int hyperv_sendpacket(struct hv_device *hdev, struct synthvid_msg
>   			       VM_PKT_DATA_INBAND, 0);
>   
>   	if (ret)
> -		drm_err(&hv->dev, "Unable to send packet via vmbus\n");
> +		drm_err_ratelimited(&hv->dev, "Unable to send packet via vmbus; error %d\n", ret);

I better option would probably be drm_err_once(). Then you'd get the 
first error message and skip all others.

Best regards
Thomas

>   
>   	return ret;
>   }

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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