[PATCH v2] kni: use netif_rx instead of netif_receive_skb in which ocurr deallock on userpace contex

[PATCH v2] kni: use netif_rx instead of netif_receive_skb in which ocurr deallock on userpace contex

[Yao-Po Wang]

Per netif_receive_skb function description, it may only be called from
interrupt contex, but KNI is run on kthread that like as user-space
contex. It may occur deallock, if netif_receive_skb called from kthread,
so it should be repleaced by netif_rx or adding local_bh_disable/enable
around netif_receive_skb.

Signed-off-by: Yao-Po Wang <blue119-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 lib/librte_eal/linuxapp/kni/kni_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/librte_eal/linuxapp/kni/kni_net.c b/lib/librte_eal/linuxapp/kni/kni_net.c
index d3c0190..28cc5ab 100644
--- a/lib/librte_eal/linuxapp/kni/kni_net.c
+++ b/lib/librte_eal/linuxapp/kni/kni_net.c
@@ -179,7 +179,7 @@ kni_net_rx_normal(struct kni_dev *kni)
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 			/* Call netif interface */
-			netif_receive_skb(skb);
+			netif_rx(skb);
 
 			/* Update statistics */
 			kni->stats.rx_bytes += len;
-- 
2.0.0

Re: [PATCH v2] kni: use netif_rx instead of netif_receive_skb in which ocurr deallock on userpace contex

[Thomas Monjalon]

Hi,

2014-07-11 23:37, Yao-Po Wang:
> Per netif_receive_skb function description, it may only be called from
> interrupt contex, but KNI is run on kthread that like as user-space
> contex. It may occur deallock, if netif_receive_skb called from kthread,
> so it should be repleaced by netif_rx or adding local_bh_disable/enable
> around netif_receive_skb.
> 
> Signed-off-by: Yao-Po Wang <blue119-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

> --- a/lib/librte_eal/linuxapp/kni/kni_net.c
> +++ b/lib/librte_eal/linuxapp/kni/kni_net.c
>  			/* Call netif interface */
> -			netif_receive_skb(skb);
> +			netif_rx(skb);

Is there someone confident to approve this change?

-- 
Thomas

Re: [PATCH v2] kni: use netif_rx instead of netif_receive_skb in which ocurr deallock on userpace contex

[Alex Markuze]

On Thu, Jul 17, 2014 at 3:02 PM, Thomas Monjalon
<thomas.monjalon-pdR9zngts4EAvxtiuMwx3w@public.gmane.org> wrote:
> Hi,
>
> 2014-07-11 23:37, Yao-Po Wang:
>> Per netif_receive_skb function description, it may only be called from
>> interrupt contex, but KNI is run on kthread that like as user-space
>> contex. It may occur deallock, if netif_receive_skb called from kthread,
>> so it should be repleaced by netif_rx or adding local_bh_disable/enable
>> around netif_receive_skb.
>>
>> Signed-off-by: Yao-Po Wang <blue119-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>
>> --- a/lib/librte_eal/linuxapp/kni/kni_net.c
>> +++ b/lib/librte_eal/linuxapp/kni/kni_net.c
>>                       /* Call netif interface */
>> -                     netif_receive_skb(skb);
>> +                     netif_rx(skb);
>
> Is there someone confident to approve this change?

Yao-Po is correct.

Please see this comment In Linux source code .
http://lxr.free-electrons.com/source/net/core/dev.c#L3715

Context:
All todays network drivers use(ixgbe is no exception) NAPI which is a
soft irq context of the receive flow .
This is the context in which netif_receive_skb should be called in.
KNI is not soft IRQ context so the generic netif_rx is the
right function.

>
> --
> Thomas

Re: [PATCH v2] kni: use netif_rx instead of netif_receive_skb in which ocurr deallock on userpace contex

[Thomas Monjalon]

2014-07-17 15:24, Alex Markuze:
> On Thu, Jul 17, 2014 at 3:02 PM, Thomas Monjalon
> > 2014-07-11 23:37, Yao-Po Wang:
> >> Per netif_receive_skb function description, it may only be called from
> >> interrupt contex, but KNI is run on kthread that like as user-space
> >> contex. It may occur deallock, if netif_receive_skb called from kthread,
> >> so it should be repleaced by netif_rx or adding local_bh_disable/enable
> >> around netif_receive_skb.
> >>
> >> Signed-off-by: Yao-Po Wang <blue119-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> >
> >> --- a/lib/librte_eal/linuxapp/kni/kni_net.c
> >> +++ b/lib/librte_eal/linuxapp/kni/kni_net.c
> >>                       /* Call netif interface */
> >> -                     netif_receive_skb(skb);
> >> +                     netif_rx(skb);
> >
> > Is there someone confident to approve this change?
> 
> Yao-Po is correct.
> 
> Please see this comment In Linux source code .
> http://lxr.free-electrons.com/source/net/core/dev.c#L3715
> 
> Context:
> All todays network drivers use(ixgbe is no exception) NAPI which is a
> soft irq context of the receive flow .
> This is the context in which netif_receive_skb should be called in.
> KNI is not soft IRQ context so the generic netif_rx is the
> right function.

Thanks for confirmation.
Assuming Acked-by: Alex Markuze <alex-I7wstvAgZDk@public.gmane.org>

Applied for version 1.7.1

Thanks
-- 
Thomas