[dpdk-stable] [PATCH v3 1/3] net/virtio: add missing barrier before reading the flags

[Maxime Coquelin]

On 1/9/19 3:50 PM, Ilya Maximets wrote:
> Reading the used->flags could be reordered with avail->idx update.
> vhost in kernel disables notifications for the time of packets
> receiving, like this:
> 
>      1. disable notify
>      2. process packets
>      3. enable notify
>      4. has more packets ? goto 1
> 
> In case of reordering, virtio driver could read the flags on
> step 2 while notifications disabled and update avail->idx after
> the step 4, i.e. vhost will exit the loop on step 4 with
> notifications enabled, but virtio will not notify.
> 
> Fixes: c1f86306a026 ("virtio: add new driver")
> CC: stable at dpdk.org
> 
> Reported-by: Shahaf Shuler <shahafs at mellanox.com>
> Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
> ---
>   drivers/net/virtio/virtqueue.h | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks,
Maxime