linux-kernel - Re: [PATCH net-next 2/3] udp_tunnel: remove rtnl

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Message-ID: <20250521153107.150f01e1@kernel.org>
Date: Wed, 21 May 2025 15:31:07 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Stanislav Fomichev <stfomichev@...il.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
 pabeni@...hat.com, skalluru@...vell.com, manishc@...vell.com,
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Subject: Re: [PATCH net-next 2/3] udp_tunnel: remove rtnl_lock dependency

On Wed, 21 May 2025 09:54:03 -0700 Stanislav Fomichev wrote:
> > >  enum udp_tunnel_nic_info_flags {
> > > -	/* Device callbacks may sleep */
> > > -	UDP_TUNNEL_NIC_INFO_MAY_SLEEP	= BIT(0),  
> > 
> > Could we use a different lock for sleeping and non-sleeping drivers?  
> 
> We can probably do it if we reorder the locks (as you ask/suggest
> below). Overall, I'm not sure I understand why we want to have two
> paths here. If we can do everything via work queue, why have a separate
> path for the non-sleepable callback? (more code -> more bugs)

I think when I was pulling this code out of the drivers I was trying 
to preserve the fast path for drivers which don't have to sleep.
But if some drivers are okay with the wq then the mechanism must work,
so I guess you're right, it should be fine to make all go via wq.