netdev - Re: [PATCH] net: set struct net

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Message-ID: <a075e64d-1297-4dc9-81b4-8b67f3db3cae@lunn.ch>
Date: Sun, 19 May 2024 15:42:49 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Alexey Dobriyan <adobriyan@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH] net: set struct net_device::name earlier

On Sun, May 19, 2024 at 08:41:40AM +0300, Alexey Dobriyan wrote:
> On Sun, May 19, 2024 at 12:04:05AM +0200, Andrew Lunn wrote:
> > On Sat, May 18, 2024 at 11:24:57PM +0300, Alexey Dobriyan wrote:
> > > I've tried debugging networking allocations with bpftrace and doing
> > > 
> > > 	$dev = (struct net_device*)arg0;
> > > 	printf("dev %s\n", $dev->name);
> > > 
> > > doesn't print anything useful in functions called right after netdevice
> > > allocation. The reason is very simple: dev->name has not been set yet.
> > > 
> > > Make name copying much earlier for smoother debugging experience.
> > 
> > Does this really help?
> 
> Yes and no. One could infer names from stacktraces and overall ordering
> of the allocations but it isn't convenient.
> 
> The snippet works everywhere except small number of functions
> but it doesn't cost anything to make it work everywhere.
> 
> > Instead of "" don't you get "eth%d"? The expansion of the %d to eth42
> > does not happen until you register the netdev.
> 
> Expansion happens later, yes. %d is fine. It is immediately obvious
> which type of device allocates what.

We are in the merge window at the moment, so patches are not being
accepted at the moment. You will need to repost in a weeks time. When
you do, please expand the commit message. The "which type of device"
is what is important here, not the true device name.

Also, please take a look at:

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html

	Andrew