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tun offloads bug

Message ID CADS+iDXrkp6vrj9dAYQqnGPm+-RYizYz_iEW0LEkqdXsxBfV2Q@mail.gmail.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Yaroslav Isakov March 16, 2017, 6:23 p.m. UTC 
Hello! I'm sending new patch, with proper formatting and signed tag

2017-03-08 23:29 GMT+03:00 Yaroslav Isakov <yaroslav.isakov@gmail.com>:
> Hello!
> I've found a bug in TUN/TAP driver with offloads - when Qemu is trying
> to set offloads on tap device, there is no error, but offloads are not
> appied.
>
> The cause of this is that udev in recent systemd is using ethtool to
> disable offloads. So, udev is setting tun->dev->wanted_features via
> ethtool ioctl to disable TSO, but when qemu is trying to set offloads,
> it's using TUN/TAP ioctl which is not setting wanted_features, so
> netdev_update_features will not see features qemu wants.
>
> This can be easily reproduced - just run qemu with
> guest_tso4=on,guest_tso6=on on systemd with systemd>=226 and after
> booting the VM, ethtool -k tap0 will show that TSO4 is disabled and
> TSO6 is enabled (systemd is not touching TSO6, that's why it's not
> affected at all)
> I've attached pretty trivial patch to fix this problem.

Comments

David Miller March 16, 2017, 7:12 p.m. UTC | #1 
This is not how you resubmit a patch.

You must make a fresh patch posting to the mailing list, provide the
commit message and patch as inline text, and not do it as a reply to
another posting.

Thank you.
Yaroslav Isakov March 16, 2017, 7:14 p.m. UTC | #2 
Sorry for this mess! I'll do it properly this time, I hope :)

2017-03-16 22:12 GMT+03:00 David Miller <davem@davemloft.net>:
>
> This is not how you resubmit a patch.
>
> You must make a fresh patch posting to the mailing list, provide the
> commit message and patch as inline text, and not do it as a reply to
> another posting.
>
> Thank you.
diff mbox

Patch

From 12a5079ef6172c32ac19b606310db151c7ca3e5d Mon Sep 17 00:00:00 2001
From: Yaroslav Isakov <yaroslav.isakov@gmail.com>
Date: Thu, 16 Mar 2017 21:08:37 +0300
Subject: [PATCH] tun: fix inability to set offloads after disabling them via
 ethtool

From: Yaroslav Isakov <yaroslav.isakov@gmail.com>

Added missing logic in tun driver, which prevents apps to set
offloads using tun ioctl, if offloads were previously disabled via ethtool

Signed-off-by: Yaroslav Isakov <yaroslav.isakov@gmail.com>
---
 drivers/net/tun.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 34cc3c5..cc88cd7 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1931,6 +1931,8 @@  static int set_offload(struct tun_struct *tun, unsigned long arg)
 		return -EINVAL;
 
 	tun->set_features = features;
+	tun->dev->wanted_features &= ~TUN_USER_FEATURES;
+	tun->dev->wanted_features |= features;
 	netdev_update_features(tun->dev);
 
 	return 0;
-- 
2.10.2