Re: [PATCH 1/1] video: hyperv_fb: Add ratelimit on error message

[Joe Perches]

On Tue, 2021-04-20 at 08:44 -0700, Michael Kelley wrote:
> 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.  As a result, in some circumstances the error message is output
> continuously.
> 
> Break the cycle by rate limiting the error message.  Also output
> the error code for additional diagnosability.
> 
> Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>

None of the callers of this function ever check the return status.
Why is important/useful to emit this message at all?

> ---
>  drivers/video/fbdev/hyperv_fb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
> index 4dc9077..a7e6eea 100644
> --- a/drivers/video/fbdev/hyperv_fb.c
> +++ b/drivers/video/fbdev/hyperv_fb.c
> @@ -308,7 +308,7 @@ static inline int synthvid_send(struct hv_device *hdev,
>  			       VM_PKT_DATA_INBAND, 0);
>  
> 
>  	if (ret)
> -		pr_err("Unable to send packet via vmbus\n");
> +		pr_err_ratelimited("Unable to send packet via vmbus; error %d\n", ret);
>  
> 
>  	return ret;
>  }