linux-kernel - Re: [PATCH net] vsock/test: Do not filter kallsyms by symbol type

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Message-ID: <aWoKNf1AI9s1bmYM@sgarzare-redhat>
Date: Fri, 16 Jan 2026 11:11:20 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
Cc: Luigi Leonardi <leonardi@...hat.com>, Jakub Kicinski <kuba@...nel.org>, 
	virtualization@...ts.linux.dev, netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] vsock/test: Do not filter kallsyms by symbol type

On Fri, Jan 16, 2026 at 09:52:36AM +0100, Michal Luczaj wrote:
>Blamed commit implemented logic to discover available vsock transports by
>grepping /proc/kallsyms for known symbols. It incorrectly filtered entries
>by type 'd'.
>
>For some kernel configs having
>
>    CONFIG_VIRTIO_VSOCKETS=m
>    CONFIG_VSOCKETS_LOOPBACK=y
>
>kallsyms reports
>
>    0000000000000000 d virtio_transport	[vmw_vsock_virtio_transport]
>    0000000000000000 t loopback_transport
>
>Overzealous filtering might have affected vsock test suit, resulting in
>insufficient/misleading testing.
>
>Do not filter symbols by type. It never helped much.
>
>Fixes: 3070c05b7afd ("vsock/test: Introduce get_transports()")
>Signed-off-by: Michal Luczaj <mhal@...x.co>
>---
>man nm says: 't' stands for symbol is in the text (code) section. Is this
>correct for `static struct virtio_transport loopback_transport`?

I'm not an expert, but yeah I was expecting "d" too, but maybe since
it's static and built-in will be in the text section?

BTW I just checked and for example on my 6.18.4-100.fc42.x86_64 I have:

0000000000000000 t sock_fs_type
0000000000000000 t proto_net_ops
0000000000000000 t net_inuse_ops

And they are all static structs of built-in modules.
So it seems it is common.

>---
> tools/testing/vsock/util.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks for the fix!

Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

>
>diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
>index 142c02a6834a..bf633cde82b0 100644
>--- a/tools/testing/vsock/util.h
>+++ b/tools/testing/vsock/util.h
>@@ -25,7 +25,7 @@ enum transport {
> };
>
> static const char * const transport_ksyms[] = {
>-	#define x(name, symbol) "d " symbol "_transport",
>+	#define x(name, symbol) " " symbol "_transport",
> 	KNOWN_TRANSPORTS(x)
> 	#undef x
> };
>
>---
>base-commit: a74c7a58ca2ca1cbb93f4c01421cf24b8642b962
>change-id: 20260113-vsock_test-kallsyms-grep-e08cd920621d
>
>Best regards,
>-- 
>Michal Luczaj <mhal@...x.co>
>