Re: [PATCH v2] tun: Use netif_receive_skb instead of netif_rx

[Jason Wang]

On 2016å12æ02æ 03:43, David Miller wrote:
> From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Date: Thu,  1 Dec 2016 10:34:40 +0100
>
> > This patch changes tun.c to call netif_receive_skb instead of netif_rx
> > when a packet is received (if CONFIG_4KSTACKS is not enabled to avoid
> > stack exhaustion). The difference between the two is that netif_rx queues
> > the packet into the backlog, and netif_receive_skb proccesses the packet
> > in the current context.
> >
> > This patch is required for syzkaller [1] to collect coverage from packet
> > receive paths, when a packet being received through tun (syzkaller collects
> > coverage per process in the process context).
> >
> > As mentioned by Eric this change also speeds up tun/tap. As measured by
> > Peter it speeds up his closed-loop single-stream tap/OVS benchmark by
> > about 23%, from 700k packets/second to 867k packets/second.
> >
> > A similar patch was introduced back in 2010 [2, 3], but the author found
> > out that the patch doesn't help with the task he had in mind (for cgroups
> > to shape network traffic based on the original process) and decided not to
> > go further with it. The main concern back then was about possible stack
> > exhaustion with 4K stacks.
> >
> > [1] https://github.com/google/syzkaller
> >
> > [2] https://www.spinics.net/lists/netdev/thrd440.html#130570
> >
> > [3] https://www.spinics.net/lists/netdev/msg130570.html
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > ---
> >
> > Changes since v1:
> > - incorporate Eric's note about speed improvements in commit description
> > - use netif_receive_skb CONFIG_4KSTACKS is not enabled
> Applied to net-next, thanks!

David, looks like this commit is not in net-next.git.

Please help to check.

Thanks