Hi David,
On 12/11/2017 09:23 PM, David Miller wrote:
From: "Michael S. Tsirkin"
Date: Tue, 5 Dec 2017 21:29:37 +0200
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier
From: "Michael S. Tsirkin"
Date: Tue, 5 Dec 2017 21:29:37 +0200
> Users of ptr_ring expect that it's safe to give the
> data structure a pointer and have it be available
> to consumers, but that actually requires an smb_wmb
> or a stronger barrier.
>
> In absence of such barriers and on architec
From: "Michael S. Tsirkin"
Date: Tue, 5 Dec 2017 21:29:37 +0200
> Users of ptr_ring expect that it's safe to give the
> data structure a pointer and have it be available
> to consumers, but that actually requires an smb_wmb
> or a stronger barrier.
>
> In absence of such barriers and on architec
On Wed, Dec 06, 2017 at 02:08:54PM +, Cherian, George wrote:
> > @@ -275,6 +281,13 @@ static inline void *__ptr_ring_consume(struct ptr_ring
> *r)
> > if (ptr)
> > __ptr_ring_discard_one(r);
> >
> > + /*
> > + * This barrier is necessary in order to prevent race condition with
> > + * with __pt
On Wed, Dec 06, 2017 at 09:57:41AM +, George Cherian wrote:
> While running a multiple VM testscase with each VM running iperf
> traffic between others the following kernel NULL pointer exception
> was seen.
>
> Race appears when the tun driver instance of one VM calls skb_array_produce
> (fro
On Wed, Dec 06, 2017 at 02:51:41PM +0530, George Cherian wrote:
> Hi Michael,
>
>
> On 12/06/2017 12:59 AM, Michael S. Tsirkin wrote:
> > Users of ptr_ring expect that it's safe to give the
> > data structure a pointer and have it be available
> > to consumers, but that actually requires an smb_w
While running a multiple VM testscase with each VM running iperf
traffic between others the following kernel NULL pointer exception
was seen.
Race appears when the tun driver instance of one VM calls skb_array_produce
(from tun_net_xmit) and the the destined VM's skb_array_consume
(from tun_ring_r
Hi Michael,
On 12/06/2017 12:59 AM, Michael S. Tsirkin wrote:
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier.
This is not the exact situation we are seeing.
Let me t
On 2017年12月06日 10:53, Michael S. Tsirkin wrote:
On Wed, Dec 06, 2017 at 10:31:39AM +0800, Jason Wang wrote:
On 2017年12月06日 03:29, Michael S. Tsirkin wrote:
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually re
On Wed, Dec 06, 2017 at 10:31:39AM +0800, Jason Wang wrote:
>
>
> On 2017年12月06日 03:29, Michael S. Tsirkin wrote:
> > Users of ptr_ring expect that it's safe to give the
> > data structure a pointer and have it be available
> > to consumers, but that actually requires an smb_wmb
> > or a stronger
On 2017年12月06日 03:29, Michael S. Tsirkin wrote:
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier.
In absence of such barriers and on architectures that reorder writes,
Users of ptr_ring expect that it's safe to give the
data structure a pointer and have it be available
to consumers, but that actually requires an smb_wmb
or a stronger barrier.
In absence of such barriers and on architectures that reorder writes,
consumer might read an un=initialized value from an
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