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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: Wed, 18 Aug 2021 11:03:09 +0300	[thread overview]
Message-ID: <YRy+vc6nAZadagxT@unreal> (raw)
In-Reply-To: <20210816090700.313a54ba@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

On Mon, Aug 16, 2021 at 09:07:00AM -0700, Jakub Kicinski wrote:
> On Mon, 16 Aug 2021 18:53:45 +0300 Leon Romanovsky wrote:
> > 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".
> 
> IIUC that'd mean setting eswitch mode would hold write lock on 
> the dl instance. What locks does e.g. registering a dl port take 
> then?

write lock, because we are adding port to devlink->port_list.
   9099 int devlink_port_register(struct devlink *devlink,
   9100                           struct devlink_port *devlink_port,
   9101                           unsigned int port_index)
   9102 {
   ...
   9115         list_add_tail(&devlink_port->list, &devlink->port_list);

  parent reply	other threads:[~2021-08-18  8:05 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
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 [this message]
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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