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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <c5de33a3cd1dc18688fc2bb7cf6a84aedcc5a041.camel@perches.com>
Date:   Tue, 20 Apr 2021 12:58:48 -0700
From:   Joe Perches <joe@...ches.com>
To:     Michael Kelley <mikelley@...rosoft.com>, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 1/1] video: hyperv_fb: Add ratelimit on error message

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@...rosoft.com>

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;
>  }