From: David Miller <davem@davemloft.net>
To: stephen@networkplumber.org
Cc: netdev@vger.kernel.org, haiyangz@microsoft.com,
linux-kernel@vger.kernel.org, devel@linuxdriverproject.org
Subject: Re: [RFC 1/2] netvsc: reference counting fix
Date: Sun, 14 Aug 2016 21:31:33 -0700 (PDT) [thread overview]
Message-ID: <20160814.213133.1692896664092434326.davem@davemloft.net> (raw)
In-Reply-To: <20160813113559.617b7c55@xeon-e3>
From: Stephen Hemminger <stephen@networkplumber.org>
Date: Sat, 13 Aug 2016 11:35:59 -0700
> This is how I think it should be fixed, but not tested yet.
>
> Subjec: netvsc: use device not module reference counts
>
> Fix how the cross-device reference counting is handled. When VF is
> associated with the synthetic interface, the VF driver module should
> still be able to be unloaded. The module unload code will callback
> with NETDEV_UNREGISTER event which breaks the connection safely.
> (Fixes 9f4b5ba5db4 hv_netvsc: Implement support for VF drivers on Hyper-V)
>
> Signed-off-by: Stephen Hemminger <sthemmin@linuxonhyperv.com>
This might not work.
It is assumed that when a netdev unregister happens, it may be done so
at any point in time.
Therefore that NETDEV_UNREGISTER event must eliminate any and all
references to a given netdev. And that works perfectly fine right now
with all existing subsystems that take references to netdevs.
You'll have to add something so that a NETDEV_UNREGISTER event tears
this VF down and thus releases it's reference to the synthetic device.
next prev parent reply other threads:[~2016-08-15 4:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-11 10:58 [PATCH net 0/4] hv_netvsc: fixes for VF removal path Vitaly Kuznetsov
2016-08-11 10:58 ` [PATCH net 1/4] hv_netvsc: don't lose VF information Vitaly Kuznetsov
2016-08-11 15:38 ` Haiyang Zhang
2016-08-11 10:58 ` [PATCH net 2/4] hv_netvsc: reset vf_inject on VF removal Vitaly Kuznetsov
2016-08-11 11:46 ` Yuval Mintz
2016-08-11 12:09 ` Vitaly Kuznetsov
2016-08-12 14:47 ` Stephen Hemminger
2016-08-11 15:38 ` Haiyang Zhang
2016-08-13 3:40 ` David Miller
2016-08-13 18:35 ` [RFC 1/2] netvsc: reference counting fix Stephen Hemminger
2016-08-13 18:38 ` [RFC 2/2] netvsc: use RCU for VF net device reference Stephen Hemminger
2016-08-15 10:06 ` Vitaly Kuznetsov
2016-08-15 4:31 ` David Miller [this message]
2016-08-11 10:58 ` [PATCH net 3/4] hv_netvsc: protect module refcount by checking net_device_ctx->vf_netdev Vitaly Kuznetsov
2016-08-11 15:38 ` Haiyang Zhang
2016-08-11 10:58 ` [PATCH net 4/4] hv_netvsc: avoid deadlocks between rtnl lock and netvsc_inject_disable() Vitaly Kuznetsov
2016-08-11 15:38 ` Haiyang Zhang
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