From: Eric Dumazet <eric.dumazet@gmail.com>
To: Ben Greear <greearb@candelatech.com>
Cc: David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] net/hyperv: fix erroneous NETDEV_TX_BUSY use
Date: Wed, 14 Mar 2012 12:17:12 -0700 [thread overview]
Message-ID: <1331752632.6022.49.camel@edumazet-glaptop> (raw)
In-Reply-To: <4F60E9F7.4000402@candelatech.com>
On Wed, 2012-03-14 at 11:56 -0700, Ben Greear wrote:
> On 03/14/2012 11:53 AM, Eric Dumazet wrote:
> > A driver start_xmit() method cannot free skb and return NETDEV_TX_BUSY,
> > since caller is going to reuse freed skb.
> >
> > This is mostly a revert of commit bf769375c (staging: hv: fix the return
> > status of netvsc_start_xmit())
> >
> > In fact netif_tx_stop_queue() / netif_stop_queue() is needed before
> > returning NETDEV_TX_BUSY or you can trigger a ksoftirqd fatal loop.
> >
> > In case of memory allocation error, only safe way is to drop the packet
> > and return NETDEV_TX_OK
>
> Can you not just leave the skb alone, not bump any tx-dropped
> stats, and return NETDEV_TX_BUSY?
>
Nope. Think about OOM.
If we do that, we requeue packet on qdisc, and schedule TX softirq.
-> loop
Really, NETDEV_TX_BUSY is not for this kind of situation.
next prev parent reply other threads:[~2012-03-14 19:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-14 18:53 [PATCH] net/hyperv: fix erroneous NETDEV_TX_BUSY use Eric Dumazet
2012-03-14 18:56 ` Ben Greear
2012-03-14 19:17 ` Eric Dumazet [this message]
2012-03-14 20:00 ` Haiyang Zhang
2012-03-14 20:14 ` Eric Dumazet
2012-03-14 20:29 ` Haiyang Zhang
2012-03-16 9:02 ` David Miller
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