Re: [RFT net-next 1/6] devlink: expose instance locking and add locked port registering

From: Jakub Kicinski <kuba@kernel.org>
To: Leon Romanovsky <leonro@nvidia.com>
Cc: <idosch@nvidia.com>, <petrm@nvidia.com>,
	<simon.horman@corigine.com>, <netdev@vger.kernel.org>,
	<jiri@resnulli.us>
Subject: Re: [RFT net-next 1/6] devlink: expose instance locking and add locked port registering
Date: Fri, 11 Mar 2022 10:06:11 -0800	[thread overview]
Message-ID: <20220311100611.2993ff4e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <YiuLsDa4jej7bVEz@unreal>

On Fri, 11 Mar 2022 19:49:36 +0200 Leon Romanovsky wrote:
> > No, no, that function is mostly for rcu dereference checking.
> > The calls should be eliminated as dead code on production systems.  
> 
> On systems without LOCKDEP, the devl_lock_is_held function will be
> generated to be like this:
> bool devl_lock_is_held(struct devlink *devlink)
> {
> 	return WARN_ON_ONCE(true);
> }
> EXPORT_SYMBOL_GPL(devl_lock_is_held);

I think you missed my first sentence. Anyway, this is what I'll do in
v1:

#ifdef CONFIG_LOCKDEP
/* For use in conjunction with LOCKDEP only e.g. rcu_dereference_protected() */
bool devl_lock_is_held(struct devlink *devlink)
{
	return lockdep_is_held(&devlink->lock);
}
EXPORT_SYMBOL_GPL(devl_lock_is_held);
#endif