[net-next PATCH v2] igb: remove skb_orphan calls

[net-next PATCH v2] igb: remove skb_orphan calls

[Jeff Kirsher]

From: Alexander Duyck <alexander.h.duyck@intel.com>

Remove skb_orphan call from igb driver as it can cause multiple issues due
to the fact that it is calling the desctructor and removing the skb from
the socket prior to transmission.

The call was added to improve performance but did so by allowing the skb to
be removed from the socket which gave the socket more window space to
transmit.  The performance gain is not worth the extra problems that this
kind of workaround can introduce as this could lead to a potential DoS if a
UDP stream decided to monopolize the transmit path.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---

 drivers/net/igb/igb_main.c |   11 -----------
 1 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/drivers/net/igb/igb_main.c b/drivers/net/igb/igb_main.c
index 6cae258..78558f8 100644
--- a/drivers/net/igb/igb_main.c
+++ b/drivers/net/igb/igb_main.c
@@ -3258,14 +3258,6 @@ static int igb_xmit_frame_ring_adv(struct sk_buff *skb,
 	if (unlikely(shtx->hardware)) {
 		shtx->in_progress = 1;
 		tx_flags |= IGB_TX_FLAGS_TSTAMP;
-	} else if (likely(!shtx->software)) {
-		/*
-		 * TODO: can this be solved in dev.c:dev_hard_start_xmit()?
-		 * There are probably unmodified driver which do something
-		 * like this and thus don't work in combination with
-		 * SOF_TIMESTAMPING_TX_SOFTWARE.
-		 */
-		skb_orphan(skb);
 	}
 
 	if (adapter->vlgrp && vlan_tx_tag_present(skb)) {
@@ -4253,9 +4245,6 @@ static void igb_tx_hwtstamp(struct igb_adapter *adapter, struct sk_buff *skb)
 				timecompare_transform(&adapter->compare, ns);
 			skb_tstamp_tx(skb, &shhwtstamps);
 		}
-
-		/* delayed orphaning: skb_tstamp_tx() needs the socket */
-		skb_orphan(skb);
 	}
 }
 

Re: [net-next PATCH v2] igb: remove skb_orphan calls

[David Miller]

From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Date: Mon, 02 Mar 2009 15:44:04 -0800

> From: Alexander Duyck <alexander.h.duyck@intel.com>
> 
> Remove skb_orphan call from igb driver as it can cause multiple issues due
> to the fact that it is calling the desctructor and removing the skb from
> the socket prior to transmission.
> 
> The call was added to improve performance but did so by allowing the skb to
> be removed from the socket which gave the socket more window space to
> transmit.  The performance gain is not worth the extra problems that this
> kind of workaround can introduce as this could lead to a potential DoS if a
> UDP stream decided to monopolize the transmit path.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Acked-by: Mitch Williams <mitch.a.williams@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Applied.