From: Eric Dumazet <eric.dumazet@gmail.com>
To: Marcin Wojtas <mw@semihalf.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
davem@davemloft.net, linux@arm.linux.org.uk,
sebastian.hesselbarth@gmail.com, andrew@lunn.ch,
jason@lakedaemon.net, thomas.petazzoni@free-electrons.com,
gregory.clement@free-electrons.com, nadavh@marvell.com,
alior@marvell.com, simon.guinot@sequanux.org,
nitroshift@yahoo.com, jaz@semihalf.com
Subject: Re: [PATCH net-next 1/2] net: mvneta: add xmit_more support
Date: Tue, 13 Sep 2016 07:42:28 -0700 [thread overview]
Message-ID: <1473777748.18970.120.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <1473777182.18970.118.camel@edumazet-glaptop3.roam.corp.google.com>
On Tue, 2016-09-13 at 07:33 -0700, Eric Dumazet wrote:
> Hi Marcin
>
> Well, given the above comment, and fact that MVNETA_MAX_TXD == 532, it
> looks like you might add a bug if more than 256 skb are given to your
> ndo_start_xmit() with skb->xmit_more = 1
>
> I therefore suggest you make sure it does not happen.
>
> txq->pending += frags;
> if (!skb->xmit_more ||
> txq->pending > 256 - MVNETA_MAX_SKB_DESCS ||
> netif_xmit_stopped(nq))
> mvneta_txq_pend_desc_add(pp, txq)
>
Another solution would be to test the potential overflow in mvneta_tx()
and force a mvneta_txq_pend_desc_add(pp, txq) _before_ adding the desc
of the "about to be cooked" TSO packet.
(This is because MVNETA_MAX_SKB_DESCS is 217, so 255-217 leaves few room
for xmit_more to show its power)
WARNING: multiple messages have this Message-ID (diff)
From: eric.dumazet@gmail.com (Eric Dumazet)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH net-next 1/2] net: mvneta: add xmit_more support
Date: Tue, 13 Sep 2016 07:42:28 -0700 [thread overview]
Message-ID: <1473777748.18970.120.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <1473777182.18970.118.camel@edumazet-glaptop3.roam.corp.google.com>
On Tue, 2016-09-13 at 07:33 -0700, Eric Dumazet wrote:
> Hi Marcin
>
> Well, given the above comment, and fact that MVNETA_MAX_TXD == 532, it
> looks like you might add a bug if more than 256 skb are given to your
> ndo_start_xmit() with skb->xmit_more = 1
>
> I therefore suggest you make sure it does not happen.
>
> txq->pending += frags;
> if (!skb->xmit_more ||
> txq->pending > 256 - MVNETA_MAX_SKB_DESCS ||
> netif_xmit_stopped(nq))
> mvneta_txq_pend_desc_add(pp, txq)
>
Another solution would be to test the potential overflow in mvneta_tx()
and force a mvneta_txq_pend_desc_add(pp, txq) _before_ adding the desc
of the "about to be cooked" TSO packet.
(This is because MVNETA_MAX_SKB_DESCS is 217, so 255-217 leaves few room
for xmit_more to show its power)
next prev parent reply other threads:[~2016-09-13 14:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 7:00 [PATCH net-next 0/2] mvneta xmit_more and bql support Marcin Wojtas
2016-09-13 7:00 ` Marcin Wojtas
2016-09-13 7:00 ` [PATCH net-next 1/2] net: mvneta: add xmit_more support Marcin Wojtas
2016-09-13 7:00 ` Marcin Wojtas
2016-09-13 14:33 ` Eric Dumazet
2016-09-13 14:33 ` Eric Dumazet
2016-09-13 14:42 ` Eric Dumazet [this message]
2016-09-13 14:42 ` Eric Dumazet
2016-09-13 7:00 ` [PATCH net-next 2/2] net: mvneta: add BQL support Marcin Wojtas
2016-09-13 7:00 ` Marcin Wojtas
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