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From: Leon Romanovsky <leon@kernel•org>
To: Prabhakar Kushwaha <prabhakar.pkin@gmail•com>
Cc: "David S . Miller" <davem@davemloft•net>,
	Jakub Kicinski <kuba@kernel•org>,
	Alexandre Belloni <alexandre.belloni@bootlin•com>,
	Andrew Lunn <andrew@lunn•ch>, Ariel Elior <aelior@marvell•com>,
	Bin Luo <luobin9@huawei•com>,
	Claudiu Manoil <claudiu.manoil@nxp•com>,
	Coiby Xu <coiby.xu@gmail•com>,
	Derek Chickles <dchickles@marvell•com>,
	drivers@pensando•io, Felix Manlunas <fmanlunas@marvell•com>,
	Florian Fainelli <f.fainelli@gmail•com>,
	Geetha sowjanya <gakula@marvell•com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
	GR-everest-linux-l2@marvell•com, GR-Linux-NIC-Dev@marvell•com,
	hariprasad <hkelam@marvell•com>, Ido Schimmel <idosch@nvidia•com>,
	intel-wired-lan@lists•osuosl.org,
	Ioana Ciornei <ioana.ciornei@nxp•com>,
	Jerin Jacob <jerinj@marvell•com>,
	Jesse Brandeburg <jesse.brandeburg@intel•com>,
	Jiri Pirko <jiri@nvidia•com>, Linu Cherian <lcherian@marvell•com>,
	Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
	linux-omap@vger•kernel.org, linux-staging@lists•linux.dev,
	Manish Chopra <manishc@marvell•com>,
	Michael Chan <michael.chan@broadcom•com>,
	netdev@vger•kernel.org, oss-drivers@corigine•com,
	Richard Cochran <richardcochran@gmail•com>,
	Saeed Mahameed <saeedm@nvidia•com>,
	Salil Mehta <salil.mehta@huawei•com>,
	Satanand Burla <sburla@marvell•com>,
	Shannon Nelson <snelson@pensando•io>,
	Simon Horman <simon.horman@corigine•com>,
	Subbaraya Sundeep <sbhatta@marvell•com>,
	Sunil Goutham <sgoutham@marvell•com>,
	Taras Chornyi <tchornyi@marvell•com>,
	Tariq Toukan <tariqt@nvidia•com>,
	Tony Nguyen <anthony.l.nguyen@intel•com>,
	UNGLinuxDriver@microchip•com, Vadym Kochan <vkochan@marvell•com>,
	Vivien Didelot <vivien.didelot@gmail•com>,
	Vladimir Oltean <vladimir.oltean@nxp•com>,
	Yisen Zhuang <yisen.zhuang@huawei•com>,
	Prabhakar Kushwaha <pkushwaha@marvell•com>,
	Shai Malin <malin1024@gmail•com>, Shai Malin <smalin@marvell•com>,
	rtoshniwal@marvell•com, Omkar Kulkarni <okulkarni@marvell•com>
Subject: Re: [PATCH net-next] devlink: Set device as early as possible
Date: Tue, 10 Aug 2021 16:45:20 +0300	[thread overview]
Message-ID: <YRKC8NKClMyaQOmt@unreal> (raw)
In-Reply-To: <CAJ2QiJLJk73RDS_XwQ0FY0ODq9qXbmiEZ2Y8Fkz9vVheK4he8g@mail.gmail.com>

On Tue, Aug 10, 2021 at 06:08:51PM +0530, Prabhakar Kushwaha wrote:
> Hi Leon,

<...>

> >  struct devlink *devlink_alloc_ns(const struct devlink_ops *ops,
> > -                                size_t priv_size, struct net *net)
> > +                                size_t priv_size, struct net *net,
> > +                                struct device *dev)
> >  {
> >         struct devlink *devlink;
> >
> > -       if (WARN_ON(!ops))
> > -               return NULL;
> > -
> > +       WARN_ON(!ops || !dev);
> >         if (!devlink_reload_actions_valid(ops))
> >                 return NULL;
> >
> >         devlink = kzalloc(sizeof(*devlink) + priv_size, GFP_KERNEL);
> >         if (!devlink)
> >                 return NULL;
> > +
> > +       devlink->dev = dev;
> >         devlink->ops = ops;
> >         xa_init_flags(&devlink->snapshot_ids, XA_FLAGS_ALLOC);
> >         write_pnet(&devlink->_net, net);
> > @@ -8810,12 +8812,9 @@ EXPORT_SYMBOL_GPL(devlink_alloc_ns);
> >   *     devlink_register - Register devlink instance
> >   *
> >   *     @devlink: devlink
> > - *     @dev: parent device
> >   */
> 
> This patch is converting devlink_alloc() to devlink_alloc_register().
> 
> There are 2 APIs: devlink_alloc() and devlink_register().
> Both APIs can be used in a scenario,
>               Where devlink_alloc() can be done by code written around
> one struct dev and used by another struct dev.
> or
> This scenario is not even a valid scenario?

devlink_alloc() is used to allocated netdev structures for newly
initialized device, it is not possible to share same devlink instance
between different devices.

> 
> > -int devlink_register(struct devlink *devlink, struct device *dev)
> > +int devlink_register(struct devlink *devlink)
> >  {
> > -       WARN_ON(devlink->dev);
> > -       devlink->dev = dev;
> >         mutex_lock(&devlink_mutex);
> >         list_add_tail(&devlink->list, &devlink_list);
> >         devlink_notify(devlink, DEVLINK_CMD_NEW);
> 
> Considering device registration has been moved to devlink_alloc().
> Can the remaining code of devlink_register() be also moved in devlink_alloc()?

The line "list_add_tail(&devlink->list, &devlink_list);" makes the
devlink instance visible to the devlink netlink users. We need to be
sure that it is happening when the device is already initialized, while
devlink_alloc() is performed usually as first line in .probe() routine.

This means that we can't combine alloc an register and
devlink_alloc_register() can't be valid scenario.

Thanks

> 
> --pk

      reply	other threads:[~2021-08-10 13:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-08 18:57 [PATCH net-next] devlink: Set device as early as possible Leon Romanovsky
2021-08-09  9:07 ` Jiri Pirko
2021-08-09  9:30 ` patchwork-bot+netdevbpf
2021-08-10 12:38 ` Prabhakar Kushwaha
2021-08-10 13:45   ` Leon Romanovsky [this message]

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