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From: Leon Romanovsky <leon@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "David S . Miller" <davem@davemloft.net>,
	Guangbin Huang <huangguangbin2@huawei.com>,
	Jacob Keller <jacob.e.keller@intel.com>,
	Jiri Pirko <jiri@nvidia.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Salil Mehta <salil.mehta@huawei.com>,
	Shannon Nelson <snelson@pensando.io>,
	Yisen Zhuang <yisen.zhuang@huawei.com>,
	Yufeng Mo <moyufeng@huawei.com>
Subject: Re: [PATCH net-next 3/6] devlink: Count struct devlink consumers
Date: Mon, 16 Aug 2021 18:53:45 +0300	[thread overview]
Message-ID: <YRqKCVbjTZaSrSy+@unreal> (raw)
In-Reply-To: <20210816084741.1dd1c415@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

On Mon, Aug 16, 2021 at 08:47:41AM -0700, Jakub Kicinski wrote:
> On Sat, 14 Aug 2021 12:57:28 +0300 Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> > 
> > 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 end goal will be something like that:
1. Delete devlink lock
2. Rely on xa_lock() while grabbing devlink instance (past devlink_try_get)
3. Convert devlink->lock to be read/write lock to make sure that we can run
get query in parallel.
4. Open devlink netlink to parallel ops, ".parallel_ops = true".

Thanks


> 
> > 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.
> 

  reply	other threads:[~2021-08-16 15:55 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-14  9:57 [PATCH net-next 0/6] Devlink cleanup for delay event series Leon Romanovsky
2021-08-14  9:57 ` [PATCH net-next 1/6] devlink: Simplify devlink_pernet_pre_exit call Leon Romanovsky
2021-08-14  9:57 ` [PATCH net-next 2/6] devlink: Remove check of always valid devlink pointer Leon Romanovsky
2021-08-14  9:57 ` [PATCH net-next 3/6] devlink: Count struct devlink consumers Leon Romanovsky
2021-08-16 15:47   ` Jakub Kicinski
2021-08-16 15:53     ` Leon Romanovsky [this message]
2021-08-16 16:07       ` Jakub Kicinski
2021-08-16 21:32         ` Keller, Jacob E
2021-08-18  8:12           ` Leon Romanovsky
2021-08-18 17:50             ` Keller, Jacob E
2021-08-20 13:06               ` Leon Romanovsky
2021-08-20 20:23                 ` Keller, Jacob E
2021-08-18  8:03         ` Leon Romanovsky
2021-08-14  9:57 ` [PATCH net-next 4/6] devlink: Use xarray to store devlink instances Leon Romanovsky
2021-08-16 21:27   ` Keller, Jacob E
2021-08-14  9:57 ` [PATCH net-next 5/6] devlink: Clear whole devlink_flash_notify struct Leon Romanovsky
2021-08-16 21:29   ` Keller, Jacob E
2021-08-14  9:57 ` [PATCH net-next 6/6] net: hns3: remove always exist devlink pointer check Leon Romanovsky
2021-08-14 13:10 ` [PATCH net-next 0/6] Devlink cleanup for delay event series patchwork-bot+netdevbpf

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