From: Vitaly Kuznetsov <vkuznets@redhat•com>
To: David Miller <davem@davemloft•net>
Cc: eric.dumazet@gmail•com, netdev@vger•kernel.org,
linux-kernel@vger•kernel.org, devel@linuxdriverproject•org,
kys@microsoft•com, haiyangz@microsoft•com,
sthemmin@microsoft•com
Subject: Re: [PATCH net-next 3/4] hv_netvsc: reset net_device_ctx->nvdev with rcu_assign_pointer()
Date: Tue, 31 Oct 2017 15:50:49 +0100 [thread overview]
Message-ID: <871sljxtfa.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20171031.234459.546020444648753386.davem@davemloft.net> (David Miller's message of "Tue, 31 Oct 2017 23:44:59 +0900 (KST)")
David Miller <davem@davemloft•net> writes:
> From: Vitaly Kuznetsov <vkuznets@redhat•com>
> Date: Tue, 31 Oct 2017 15:40:06 +0100
>
>> Eric Dumazet <eric.dumazet@gmail•com> writes:
>>
>>> On Tue, 2017-10-31 at 14:42 +0100, Vitaly Kuznetsov wrote:
>>>> RCU_INIT_POINTER() is not suitable here as it doesn't give us ordering
>>>> guarantees (see the comment in rcupdate.h). This is also not a hotpath.
>>>>
>>>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat•com>
>>>> ---
>>>> drivers/net/hyperv/netvsc.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
>>>> index bfc79698b8f4..12efb3e34775 100644
>>>> --- a/drivers/net/hyperv/netvsc.c
>>>> +++ b/drivers/net/hyperv/netvsc.c
>>>> @@ -560,7 +560,7 @@ void netvsc_device_remove(struct hv_device *device)
>>>>
>>>> netvsc_revoke_buf(device, net_device);
>>>>
>>>> - RCU_INIT_POINTER(net_device_ctx->nvdev, NULL);
>>>> + rcu_assign_pointer(net_device_ctx->nvdev, NULL);
>>>
>>> I see no point for this patch.
>>>
>>> Setting a NULL pointer needs no barrier at all.
>>
>> Oh, sorry, I got confused by the comment near RCU_INIT_POINTER() in
>> rcupdate.h. Now looking at their definitions I see.
>>
>> This patch can of course be dropped from the series.
>
> Any time there is a change to the series, you must resubmit the entire
> series.
>
Sure, will do. Just wanted to give it a couple of days to see if
Microsoft guys or someone else have any comments.
Thanks,
--
Vitaly
next prev parent reply other threads:[~2017-10-31 14:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 13:42 [PATCH net-next 0/4] hv_netvsc: fix some crashes and hangs on channel/mtu changes Vitaly Kuznetsov
2017-10-31 13:42 ` [PATCH net-next 1/4] hv_netvsc: netvsc_teardown_gpadl() split Vitaly Kuznetsov
2017-10-31 16:37 ` Stephen Hemminger
2017-10-31 13:42 ` [PATCH net-next 2/4] hv_netvsc: protect nvdev->extension with RCU Vitaly Kuznetsov
2017-10-31 16:44 ` Stephen Hemminger
2017-10-31 17:13 ` Vitaly Kuznetsov
2017-11-02 10:27 ` Vitaly Kuznetsov
2017-10-31 13:42 ` [PATCH net-next 3/4] hv_netvsc: reset net_device_ctx->nvdev with rcu_assign_pointer() Vitaly Kuznetsov
2017-10-31 14:09 ` Eric Dumazet
2017-10-31 14:40 ` Vitaly Kuznetsov
2017-10-31 14:44 ` David Miller
2017-10-31 14:50 ` Vitaly Kuznetsov [this message]
2017-10-31 16:45 ` Stephen Hemminger
2017-10-31 13:42 ` [PATCH net-next 4/4] hv_netvsc: hide warnings about uninitialized/missing rndis device Vitaly Kuznetsov
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