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

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Message-Id: <1618933459-10585-1-git-send-email-mikelley@microsoft.com>
Date:   Tue, 20 Apr 2021 08:44:19 -0700
From:   Michael Kelley <mikelley@...rosoft.com>
To:     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
Cc:     mikelley@...rosoft.com
Subject: [PATCH 1/1] video: hyperv_fb: Add ratelimit on error message

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>
---
 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;
 }
-- 
1.8.3.1