From: Florian Fainelli <f.fainelli@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: netdev@vger.kernel.org, linux-mm@kvack.org,
"Toke Høiland-Jørgensen" <toke@toke.dk>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
willy@infradead.org, "Saeed Mahameed" <saeedm@mellanox.com>,
"Alexander Duyck" <alexander.duyck@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
mgorman@techsingularity.net,
"David S. Miller" <davem@davemloft.net>,
"Tariq Toukan" <tariqt@mellanox.com>
Subject: Re: [net-next PATCH V2 1/3] mm: add dma_addr_t to struct page
Date: Tue, 12 Feb 2019 10:23:52 -0800 [thread overview]
Message-ID: <2d0de75d-960c-6866-b396-86490ca479af@gmail.com> (raw)
In-Reply-To: <20190212191917.2ef91a88@carbon>
On 2/12/19 10:19 AM, Jesper Dangaard Brouer wrote:
> On Tue, 12 Feb 2019 10:05:39 -0800
> Florian Fainelli <f.fainelli@gmail.com> wrote:
>
>> On 2/12/19 6:49 AM, Jesper Dangaard Brouer wrote:
>>> The page_pool API is using page->private to store DMA addresses.
>>> As pointed out by David Miller we can't use that on 32-bit architectures
>>> with 64-bit DMA
>>>
>>> This patch adds a new dma_addr_t struct to allow storing DMA addresses
>>>
>>> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
>>> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
>>> Acked-by: Andrew Morton <akpm@linux-foundation.org>
>>> ---
>>> include/linux/mm_types.h | 7 +++++++
>>> 1 file changed, 7 insertions(+)
>>>
>>> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
>>> index 2c471a2c43fa..581737bd0878 100644
>>> --- a/include/linux/mm_types.h
>>> +++ b/include/linux/mm_types.h
>>> @@ -95,6 +95,13 @@ struct page {
>>> */
>>> unsigned long private;
>>> };
>>> + struct { /* page_pool used by netstack */
>>> + /**
>>> + * @dma_addr: page_pool requires a 64-bit value even on
>>> + * 32-bit architectures.
>>> + */
>>
>> Nit: might require? dma_addr_t, as you mention in the commit may have a
>> different size based on CONFIG_ARCH_DMA_ADDR_T_64BIT.
>
> So you want me to change the comment to be:
>
> /**
> * @dma_addr: might require a 64-bit value even on
> * 32-bit architectures.
> */
>
> Correctly understood?
Correct, that is what I would change. The commit message is correct, but
the comment makes it sound like dma_addr_t is guaranteed to be 64-bit,
while it is actually platform dependent. Does that make it clearer?
--
Florian
next prev parent reply other threads:[~2019-02-12 18:24 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 14:48 [net-next PATCH V2 0/3] Fix page_pool API and dma address storage Jesper Dangaard Brouer
2019-02-12 14:49 ` [net-next PATCH V2 1/3] mm: add dma_addr_t to struct page Jesper Dangaard Brouer
2019-02-12 18:05 ` Florian Fainelli
2019-02-12 18:19 ` Jesper Dangaard Brouer
2019-02-12 18:23 ` Florian Fainelli [this message]
2019-02-12 14:49 ` [net-next PATCH V2 2/3] net: page_pool: don't use page->private to store dma_addr_t Jesper Dangaard Brouer
2019-02-12 14:49 ` [net-next PATCH V2 3/3] page_pool: use DMA_ATTR_SKIP_CPU_SYNC for DMA mappings Jesper Dangaard Brouer
2019-02-12 17:12 ` kbuild test robot
2019-02-12 17:58 ` Jesper Dangaard Brouer
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