From: Jakub Kicinski <kuba@kernel•org>
To: Shinas Rasheed <srasheed@marvell•com>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
Haseeb Gani <hgani@marvell•com>,
Vimlesh Kumar <vimleshk@marvell•com>,
Sathesh B Edara <sedara@marvell•com>,
"egallen@redhat•com" <egallen@redhat•com>,
"mschmidt@redhat•com" <mschmidt@redhat•com>,
"pabeni@redhat•com" <pabeni@redhat•com>,
"horms@kernel•org" <horms@kernel•org>,
"wizhao@redhat•com" <wizhao@redhat•com>,
"kheib@redhat•com" <kheib@redhat•com>,
"konguyen@redhat•com" <konguyen@redhat•com>,
"David S. Miller" <davem@davemloft•net>,
Eric Dumazet <edumazet@google•com>,
Jonathan Corbet <corbet@lwn•net>,
Veerasenareddy Burru <vburru@marvell•com>,
Satananda Burla <sburla@marvell•com>,
Shannon Nelson <shannon.nelson@amd•com>,
Tony Nguyen <anthony.l.nguyen@intel•com>,
Joshua Hay <joshua.a.hay@intel•com>,
Rahul Rameshbabu <rrameshbabu@nvidia•com>,
Brett Creeley <brett.creeley@amd•com>,
Andrew Lunn <andrew@lunn•ch>,
Jacob Keller <jacob.e.keller@intel•com>
Subject: Re: [EXT] Re: [PATCH net-next v5 1/8] octeon_ep_vf: Add driver framework and device initialization
Date: Tue, 6 Feb 2024 07:21:14 -0800 [thread overview]
Message-ID: <20240206072114.244738a9@kernel.org> (raw)
In-Reply-To: <PH0PR18MB473460118D0FC68BE4B3BC45C7462@PH0PR18MB4734.namprd18.prod.outlook.com>
On Tue, 6 Feb 2024 07:42:12 +0000 Shinas Rasheed wrote:
> > > We do cancel_work_sync in octep_vf_remove function.
> >
> > But the device is still registered, so the timeout can happen after you
> > cancel but before you unregister.
>
> There is rtnl_lock inside octep_vf_tx_timeout_task (the work task
> function), which can protect from unregister_netdev, for such cases
> (code snippet for quick reference below):
>
> static void octep_vf_tx_timeout_task(struct work_struct *work)
> {
> struct octep_vf_device *oct = container_of(work, struct octep_vf_device, tx_timeout_task);
> struct net_device *netdev = oct->netdev;
>
> rtnl_lock();
> if (netif_running(netdev)) {
> octep_vf_stop(netdev);
> octep_vf_open(netdev);
> }
> rtnl_unlock();
> }
>
> I hope this takes care of it? Please let me know if my thought
> process feels wrong. Thanks!
The problem I see is that if the queue is somehow overloaded or delayed
there can be a race where we cancel, then timeout happens, work doesn't
run for a while, and we free the netdev. So what I'm suggesting is -
hold a reference on the netdevice. That way you can be sure it doesn't
get freed and you can depend on the rtnl+netif_running() doing its job.
next prev parent reply other threads:[~2024-02-06 15:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-29 5:02 [PATCH net-next v5 0/8] add octeon_ep_vf driver Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 1/8] octeon_ep_vf: Add driver framework and device initialization Shinas Rasheed
2024-02-01 0:14 ` Jakub Kicinski
2024-02-03 5:35 ` [EXT] " Shinas Rasheed
2024-02-05 23:44 ` Jakub Kicinski
2024-02-06 7:42 ` Shinas Rasheed
2024-02-06 15:21 ` Jakub Kicinski [this message]
2024-01-29 5:02 ` [PATCH net-next v5 2/8] octeon_ep_vf: add hardware configuration APIs Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 3/8] octeon_ep_vf: add VF-PF mailbox communication Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 4/8] octeon_ep_vf: add Tx/Rx ring resource setup and cleanup Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 5/8] octeon_ep_vf: add support for ndo ops Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 6/8] octeon_ep_vf: add Tx/Rx processing and interrupt support Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 7/8] octeon_ep_vf: add ethtool support Shinas Rasheed
2024-01-29 5:02 ` [PATCH net-next v5 8/8] octeon_ep_vf: update MAINTAINERS Shinas Rasheed
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