From: David Miller <davem@davemloft.net>
To: nlhintz@hotmail.com
Cc: zajec5@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH] bgmac: don't update slot on skb alloc/dma mapping error
Date: Tue, 29 Oct 2013 15:39:57 -0400 (EDT) [thread overview]
Message-ID: <20131029.153957.1658989244969068757.davem@davemloft.net> (raw)
In-Reply-To: <BLU0-SMTP200803D333FF3A2F15AB82DAC090@phx.gbl>
From: Nathan Hintz <nlhintz@hotmail.com>
Date: Tue, 29 Oct 2013 01:22:55 -0700
> On Tue, 29 Oct 2013 07:52:58 +0100
> Rafał Miłecki <zajec5@gmail.com> wrote:
>
>> 2013/10/29 Nathan Hintz <nlhintz@hotmail.com>:
>> > Don't update the slot in "bgmac_dma_rx_skb_for_slot" unless both the
>> > skb alloc and dma mapping are successful; and free the newly allocated
>> > skb if a dma mapping error occurs. This will prevent an skb leak upon
>> > returning when an error occurs.
>>
>> In case of bgmac_dma_rx_skb_for_slot failure we're giving up anyway
>> (and freeing everything), but with your patch code is simpler to
>> understand, so I'm OK with that.
>>
>> Acked-by: Rafał Miłecki <zajec5@gmail.com>
>>
>
> I might be misunderstanding; but it in the case of failure, it appeared to me
> that the currently received packet was dropped and the old skb would continue
> to be assigned to the slot and would be used to receive future packets (this
> would continue until bgmac_dma_rx_skb_for_slot was successful).
That's exactly the wanted, and most desirable, behavior for any network
driver.
If you can't allocate a new SKB, reuse the old one, because the worst
thing you can do is prioritize packet reception over making sure the
device doesn't end up with no RX slots to DMA into.
prev parent reply other threads:[~2013-10-29 19:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-29 6:44 [PATCH] bgmac: don't update slot on skb alloc/dma mapping error Nathan Hintz
2013-10-29 6:52 ` Rafał Miłecki
2013-10-29 8:22 ` Nathan Hintz
2013-10-29 8:28 ` Rafał Miłecki
2013-10-29 15:20 ` Nathan Hintz
2013-10-29 19:39 ` David Miller [this message]
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