From: Ezequiel Garcia <ezequiel.garcia@free-electrons•com>
To: David Laight <David.Laight@ACULAB•COM>,
David Miller <davem@davemloft•net>,
Russell King <linux@arm•linux.org.uk>
Cc: "netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"B38611@freescale•com" <B38611@freescale•com>,
"fabio.estevam@freescale•com" <fabio.estevam@freescale•com>
Subject: Re: [PATCH v2] net: mv643xx_eth: Fix highmem support in non-TSO egress path
Date: Thu, 22 Jan 2015 10:26:56 -0300 [thread overview]
Message-ID: <54C0FAA0.9040002@free-electrons.com> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D1CAD0E4F@AcuExch.aculab.com>
On 01/22/2015 09:40 AM, David Laight wrote:
> From: Ezequiel Garcia
>> Commit 69ad0dd7af22b61d9e0e68e56b6290121618b0fb
>> Author: Ezequiel Garcia <ezequiel.garcia@free-electrons•com>
>> Date: Mon May 19 13:59:59 2014 -0300
>>
>> net: mv643xx_eth: Use dma_map_single() to map the skb fragments
>>
>> caused a nasty regression by removing the support for highmem skb
>> fragments. By using page_address() to get the address of a fragment's
>> page, we are assuming a lowmem page. However, such assumption is incorrect,
>> as fragments can be in highmem pages, resulting in very nasty issues.
>>
>> This commit fixes this by using the skb_frag_dma_map() helper,
>> which takes care of mapping the skb fragment properly. Additionally,
>> the type of mapping is now tracked, so it can be unmapped using
>> dma_unmap_page or dma_unmap_single when appropriate.
>>
>> Fixes: 69ad0dd7af22 ("net: mv643xx_eth: Use dma_map_single() to map the skb fragments")
>> Reported-by: Russell King <rmk+kernel@arm•linux.org.uk>
>> Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons•com>
> ...
>> @@ -2048,6 +2068,11 @@ static int txq_init(struct mv643xx_eth_private *mp, int index)
>> nexti * sizeof(struct tx_desc);
>> }
>>
>> + txq->tx_desc_mapping = kcalloc(txq->tx_ring_size, sizeof(char),
>> + GFP_KERNEL);
>> + if (!txq->tx_desc_mapping)
>> + return -ENOMEM;
>> +
>> /* Allocate DMA buffers for TSO MAC/IP/TCP headers */
>> txq->tso_hdrs = dma_alloc_coherent(mp->dev->dev.parent,
>> txq->tx_ring_size * TSO_HEADER_SIZE,
>
> I'm guessing there is an error path for dma_alloc_coherent() failing.
> You've not modified it to free tx_desc_mapping.
>
Yeah, you guess right.
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-01-22 13:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-22 12:14 [PATCH v2] net: mv643xx_eth: Fix highmem support in non-TSO egress path Ezequiel Garcia
2015-01-22 12:40 ` David Laight
2015-01-22 13:26 ` Ezequiel Garcia [this message]
2015-01-22 14:33 ` [PATCH v3] " Ezequiel Garcia
2015-01-24 13:45 ` Ezequiel Garcia
2015-01-26 23:11 ` Russell King - ARM Linux
2015-01-27 0:15 ` David Miller
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