linux/drivers/vhost
Wei Xu 6e474083f3 vhost: fix skb leak in handle_rx()
Matthew found a roughly 40% tcp throughput regression with commit
c67df11f(vhost_net: try batch dequing from skb array) as discussed
in the following thread:
https://www.mail-archive.com/netdev@vger.kernel.org/msg187936.html

Eventually we figured out that it was a skb leak in handle_rx()
when sending packets to the VM. This usually happens when a guest
can not drain out vq as fast as vhost fills in, afterwards it sets
off the traffic jam and leaks skb(s) which occurs as no headcount
to send on the vq from vhost side.

This can be avoided by making sure we have got enough headcount
before actually consuming a skb from the batched rx array while
transmitting, which is simply done by moving checking the zero
headcount a bit ahead.

Signed-off-by: Wei Xu <wexu@redhat.com>
Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-02 21:31:03 -05:00
..
Kconfig tap: tap as an independent module 2017-02-11 20:59:41 -05:00
Kconfig.vringh vhost: split out vringh Kconfig 2016-08-02 16:54:28 +03:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
net.c vhost: fix skb leak in handle_rx() 2017-12-02 21:31:03 -05:00
scsi.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:08:18 -08:00
test.c Merge 4.8-rc5 into char-misc-next 2016-09-05 08:04:07 +02:00
test.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vhost.c vhost: fix end of range for access_ok 2017-11-14 23:57:39 +02:00
vhost.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vringh.c vringh: kill off ACCESS_ONCE() 2016-12-16 00:13:36 +02:00
vsock.c vhost/vsock: fix uninitialized vhost_vsock->guest_cid 2017-11-14 23:57:40 +02:00