Re: [RFC 1/2] devlink: add simple fw crash helpers

On Fri, May 22, 2020 at 10:17:38AM -0700, Jakub Kicinski wrote:

On Fri, 22 May 2020 05:20:46 +0000 Luis Chamberlain wrote:

quoted

quoted

diff --git a/net/core/Makefile b/net/core/Makefile
index 3e2c378e5f31..6f1513781c17 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile

@@ -31,7 +31,7 @@ obj-$(CONFIG_LWTUNNEL_BPF) += lwt_bpf.o
 obj-$(CONFIG_BPF_STREAM_PARSER) += sock_map.o
 obj-$(CONFIG_DST_CACHE) += dst_cache.o
 obj-$(CONFIG_HWBM) += hwbm.o
-obj-$(CONFIG_NET_DEVLINK) += devlink.o
+obj-$(CONFIG_NET_DEVLINK) += devlink.o devlink_simple_fw_reporter.o  

This was looking super sexy up to here. This is networking specific.
We want something generic for *anything* that requests firmware.

You can't be serious. It's network specific because of how the Kconfig
is named?

Kconfig? What has that to do with anything? The issue I have is that the
solution I am looking for is for it to be agnostic to the subsystem. I
have found similar firmware crashes on gpu, media, scsci.

Working for a company operating large data centers I would strongly
prefer if we didn't have ten different ways of reporting firmware
problems in the fleet.

Indeed.

quoted

I'm afraid this won't work for something generic. I don't think its
throw-away work though, the idea to provide a generic interface to
dump firmware through netlink might be nice for networking, or other
things.

But I have a feeling we'll want something still more generic than this.

Please be specific. Saying generic a lot is not helpful. The code (as
you can see in this patch) is in no way network specific. Or are you
saying there are machines out there running without netlink sockets?

No, I am saying I want something to work with any struct device.

quoted

So networking may want to be aware that a firmware crash happened as
part of this network device health thing, but firmware crashing is a
generic thing.

I have now extended my patch set to include uvents and I am more set on
that we need the taint now more than ever.

Please expect my nack if you're trying to add this to networking
drivers.

The uevent mechanism is not for networking.

The taint however is, and I'd like to undertand how it is you do not see
that an undesirable requirement for a reboot is a clear case for a taint.

The irony is you have a problem with a networking device and all the
devices your initial set touched are networking. Two of the drivers 
you touched either have or will soon have devlink health reporters
implemented.

That is all great, and I don't think its a bad idea to add
infrastructure / extend it to get more information about a firmware
crash dump. However, suggesting that devlink is the only solution we
need in the kernel without considering other subsystems is what I am
suggesting doesn't suit my needs. Networking was just the first
subsystem I am taclking now but I have patches where similar situations
happen across the kernel.

  Luis