Re: [PATCH net-next 3/6] devlink: Count struct devlink consumers

From: Jakub Kicinski
Date: Mon Aug 16 2021 - 11:47:51 EST

On Sat, 14 Aug 2021 12:57:28 +0300 Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@xxxxxxxxxx>
> The struct devlink itself is protected by internal lock and doesn't
> need global lock during operation. That global lock is used to protect
> addition/removal new devlink instances from the global list in use by
> all devlink consumers in the system.
> The future conversion of linked list to be xarray will allow us to
> actually delete that lock, but first we need to count all struct devlink
> users.

Not a problem with this set but to state the obvious the global devlink
lock also protects from concurrent execution of all the ops which don't
take the instance lock (DEVLINK_NL_FLAG_NO_LOCK). You most likely know
this but I thought I'd comment on an off chance it helps.

> The reference counting provides us a way to ensure that no new user
> space commands success to grab devlink instance which is going to be
> destroyed makes it is safe to access it without lock.