Subject: Re: [PATCH net-next 2/9] net: devlink: remove region snapshots list dependency on devlink->lock

From: Jakub Kicinski <[email-masked]>
Date: Thu, 28 Jul 2022 09:16:45 -0700

On Thu, 28 Jul 2022 10:50:29 +0200 Jiri Pirko wrote:
> >> So resolve this by removing dependency on devlink->lock for region
> >> snapshots list consistency and introduce new mutex to ensure it.  
> >
> >I was hoping to avoid per-subobject locks. What prevents us from
> >depending on the instance lock here (once the driver is converted)?  
> 
> The fact that it could be called in mlx4 from both devl locked and
> unlocked context. Basically whenever CMD to fw is called.

Ok, I guess mlx4 uses regions as proto-health reporters so too hard of
a battle to fight. Please update the commit message tho.

> What is wrong in small locks here and there when they are sufficient?

The more locks the less obvious the semantics and ordering of locking
are.