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Message-ID: <CAOJe8K3fXBH-VBJXhVgm2ne6jFPup_J7xj=9K4v9e4xiw7Ujew@mail.gmail.com>
Date: Wed, 25 Mar 2020 22:16:52 +0300
From: Denis Kirjanov <kda@...ux-powerpc.org>
To: Jesper Dangaard Brouer <brouer@...hat.com>
Cc: netdev@...r.kernel.org, hawk@...nel.org,
ilias.apalodimas@...aro.org
Subject: Re: [PATCH net-next] net: page pool: allow to pass zero flags to page_pool_init()
On 3/25/20, Jesper Dangaard Brouer <brouer@...hat.com> wrote:
> On Wed, 25 Mar 2020 17:12:55 +0300
> Denis Kirjanov <kda@...ux-powerpc.org> wrote:
>
>> page pool API can be useful for non-DMA cases like
>> xen-netfront driver so let's allow to pass zero flags to
>> page pool flags.
>>
>> Signed-off-by: Denis Kirjanov <kda@...ux-powerpc.org>
>> ---
>> net/core/page_pool.c | 36 +++++++++++++++++++-----------------
>> 1 file changed, 19 insertions(+), 17 deletions(-)
>
> The pool->p.dma_dir is only used when flag PP_FLAG_DMA_MAP is used, so
> it looks more simple to do:
Yeap, agreed. Thanks!
>
> $ git diff
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 626db912fce4..ef98372facf6 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -43,9 +43,11 @@ static int page_pool_init(struct page_pool *pool,
> * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
> * which is the XDP_TX use-case.
> */
> - if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
> - (pool->p.dma_dir != DMA_BIDIRECTIONAL))
> - return -EINVAL;
> + if (pool->p.flags & PP_FLAG_DMA_MAP) {
> + if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
> + (pool->p.dma_dir != DMA_BIDIRECTIONAL))
> + return -EINVAL;
> + }
>
>
>
>> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
>> index 10d2b25..eeeb0d9 100644
>> --- a/net/core/page_pool.c
>> +++ b/net/core/page_pool.c
>> @@ -39,27 +39,29 @@ static int page_pool_init(struct page_pool *pool,
>> if (ring_qsize > 32768)
>> return -E2BIG;
>>
>> - /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
>> - * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
>> - * which is the XDP_TX use-case.
>> - */
>> - if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
>> - (pool->p.dma_dir != DMA_BIDIRECTIONAL))
>> - return -EINVAL;
>> -
>> - if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
>> - /* In order to request DMA-sync-for-device the page
>> - * needs to be mapped
>> + if (pool->p.flags) {
>> + /* DMA direction is either DMA_FROM_DEVICE or DMA_BIDIRECTIONAL.
>> + * DMA_BIDIRECTIONAL is for allowing page used for DMA sending,
>> + * which is the XDP_TX use-case.
>> */
>> - if (!(pool->p.flags & PP_FLAG_DMA_MAP))
>> + if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
>> + (pool->p.dma_dir != DMA_BIDIRECTIONAL))
>> return -EINVAL;
>>
>> - if (!pool->p.max_len)
>> - return -EINVAL;
>> + if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) {
>> + /* In order to request DMA-sync-for-device the page
>> + * needs to be mapped
>> + */
>> + if (!(pool->p.flags & PP_FLAG_DMA_MAP))
>> + return -EINVAL;
>>
>> - /* pool->p.offset has to be set according to the address
>> - * offset used by the DMA engine to start copying rx data
>> - */
>> + if (!pool->p.max_len)
>> + return -EINVAL;
>> +
>> + /* pool->p.offset has to be set according to the address
>> + * offset used by the DMA engine to start copying rx data
>> + */
>> + }
>> }
>>
>> if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
>
>
>
> --
> Best regards,
> Jesper Dangaard Brouer
> MSc.CS, Principal Kernel Engineer at Red Hat
> LinkedIn: http://www.linkedin.com/in/brouer
>
>
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