From: Leon Romanovsky <leon@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: davem@davemloft.net, netdev@vger.kernel.org, jiri@nvidia.com,
idosch@nvidia.com, petrm@nvidia.com, simon.horman@corigine.com,
louis.peens@corigine.com
Subject: Re: [PATCH net-next 1/6] devlink: expose instance locking and add locked port registering
Date: Wed, 16 Mar 2022 20:39:28 +0200 [thread overview]
Message-ID: <YjIu4CBxEJ6UTk7c@unreal> (raw)
In-Reply-To: <20220316094859.2128c430@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On Wed, Mar 16, 2022 at 09:48:59AM -0700, Jakub Kicinski wrote:
> On Wed, 16 Mar 2022 10:29:16 +0200 Leon Romanovsky wrote:
> > Sorry that I'm asking you again same question.
> > How will this devl_lock_is_held() be used in drivers?
> >
> > Right now, if I decide to use this function in mlx5 (or in any other driver),
> > the code will be something like this:
> >
> > void func(...)
> > {
> > ....
> > if (IS_ENABLED(CONFIG_LOCKDEP))
> > if (rcu_dereference_protected(a, devl_lock_is_held(devlink) == b) {
> > ....
> > }
> >
> > The line "if (IS_ENABLED(CONFIG_LOCKDEP))" needs to be in every driver
> > or it won't compile in release mode.
>
> It follows the semantics of lockdep_is_held(), note that
> rcu_dereference_protected() makes the last parameter dead
> code with LOCKDEP=n
>
> #define RCU_LOCKDEP_WARN(c, s) do { } while (0 && (c))
Ahhh, I see, thanks for an explanation.
>
> where (c) would be devl_lock_is_held()
>
> so the call to devl_lock_is_held() is eliminated, and we
> won't get a linker error. There's no need for IS_ENABLED().
next prev parent reply other threads:[~2022-03-16 18:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-15 6:00 [PATCH net-next 0/6] devlink: expose instance locking and simplify port splitting Jakub Kicinski
2022-03-15 6:00 ` [PATCH net-next 1/6] devlink: expose instance locking and add locked port registering Jakub Kicinski
2022-03-16 8:29 ` Leon Romanovsky
2022-03-16 16:48 ` Jakub Kicinski
2022-03-16 18:39 ` Leon Romanovsky [this message]
2022-03-16 18:39 ` Leon Romanovsky
2022-03-15 6:00 ` [PATCH net-next 2/6] eth: nfp: wrap locking assertions in helpers Jakub Kicinski
2022-03-15 6:00 ` [PATCH net-next 3/6] eth: nfp: replace driver's "pf" lock with devlink instance lock Jakub Kicinski
2022-03-16 8:34 ` Leon Romanovsky
2022-03-16 16:45 ` Jakub Kicinski
2022-03-15 6:00 ` [PATCH net-next 4/6] eth: mlxsw: switch to explicit locking for port registration Jakub Kicinski
2022-03-15 8:29 ` Ido Schimmel
2022-03-15 6:00 ` [PATCH net-next 5/6] devlink: hold the instance lock in port_split / port_unsplit callbacks Jakub Kicinski
2022-03-15 8:30 ` Ido Schimmel
2022-03-15 6:00 ` [PATCH net-next 6/6] devlink: pass devlink_port to " Jakub Kicinski
2022-03-15 8:32 ` Ido Schimmel
2022-03-16 20:07 ` [PATCH net-next 0/6] devlink: expose instance locking and simplify port splitting Jakub Kicinski
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