Re: [PATCH] vsock: ratelimit unknown ioctl error message

On Fri, Oct 23, 2020 at 09:30:59PM +0000, David Laight wrote:

From: Stefano Garzarella

quoted

Sent: 23 October 2020 15:10

On Fri, Oct 23, 2020 at 01:21:13PM +0100, Colin King wrote:

quoted

From: Colin Ian King <redacted>

When exercising the kernel with stress-ng with some ioctl tests the
"Unknown ioctl" error message is spamming the kernel log at a high
rate. Rate limit this message to reduce the noise.

Signed-off-by: Colin Ian King <redacted>
---
net/vmw_vsock/af_vsock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 9e93bc201cc0..b8feb9223454 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c

@@ -2072,7 +2072,7 @@ static long vsock_dev_do_ioctl(struct file *filp,

		break;

	default:
-		pr_err("Unknown ioctl %d\n", cmd);
+		pr_err_ratelimited("Unknown ioctl %d\n", cmd);

Make sense, or maybe can we remove the error message returning only the
-EINVAL?

Isn't the canonical error for unknown ioctl codes -ENOTTY?

Oh, thanks for pointing that out!

I had not paid attention to the error returned, but looking at it I noticed that perhaps the most appropriate would be -ENOIOCTLCMD.
In the ioctl syscall we return -ENOTTY, if the callback returns -ENOIOCTLCMD.

What do you think?

Stefano