netdev - Re: [PATCH v6 4/9] bgmac: simplify/optimize rx DMA error handling

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Message-ID: <CACna6rz-b2TXMPpPdRCiyS45mfZ2pgLRNiCyPpd4XLVDfwfbEA@mail.gmail.com>
Date:	Tue, 14 Apr 2015 11:19:10 +0200
From:	Rafał Miłecki <zajec5@...il.com>
To:	Felix Fietkau <nbd@...nwrt.org>
Cc:	Network Development <netdev@...r.kernel.org>,
	Hauke Mehrtens <hauke@...ke-m.de>
Subject: Re: [PATCH v6 4/9] bgmac: simplify/optimize rx DMA error handling

On 14 April 2015 at 11:13, Felix Fietkau <nbd@...nwrt.org> wrote:
> On 2015-04-14 07:55, Rafał Miłecki wrote:
>> On 14 April 2015 at 01:42, Felix Fietkau <nbd@...nwrt.org> wrote:
>>> @@ -528,14 +524,14 @@ static void bgmac_dma_rx_ring_free(struct bgmac *bgmac,
>>>
>>>         for (i = 0; i < ring->num_slots; i++) {
>>>                 slot = &ring->slots[i];
>>> -               if (!slot->buf)
>>> +               if (!slot->dma_addr)
>>>                         continue;
>>
>> I think it breaks error path of bgmac_dma_alloc. It may happen that
>> during DMA alloc we alloc skb and then we fail to map it. In such case
>> buf should be freed. Please trace how bgmac_dma_free is used in
>> bgmac_dma_alloc.
> I don't think so: bgmac_dma_rx_skb_for_slot handles both buffer
> allocation and dma mapping. If dma mapping fails, the buffer is freed
> before any part of the slot is overwritten.

Oops, I think I just spotted a memory leak then.

If bgmac_dma_rx_skb_for_slot fails to do DMA mapping it returns an
error without freeing a skb.

-- 
Rafał
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