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From: Matthew Wilcox <willy@infradead.org>
To: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Jesper Dangaard Brouer <hawk@kernel.org>,
	netdev@vger.kernel.org, linux-mm@kvack.org,
	Shakeel Butt <shakeelb@google.com>
Subject: Re: [PATCH v2 03/24] page_pool: Add netmem_set_dma_addr() and netmem_get_dma_addr()
Date: Tue, 10 Jan 2023 18:15:42 +0000	[thread overview]
Message-ID: <Y72rTrFzDiMJLfc3@casper.infradead.org> (raw)
In-Reply-To: <CAC_iWj+bDVMptma_DjQkCZzcardXxShJ965=6zc0_6ffciQhXw@mail.gmail.com>

On Mon, Jan 09, 2023 at 07:30:30PM +0200, Ilias Apalodimas wrote:
> Hi Matthew

Hey Ilias.  Thanks for all the review!

> > -static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
> > +static inline dma_addr_t netmem_get_dma_addr(struct netmem *nmem)
> 
> Ideally, we'd like to avoid having people call these directly and use
> the page_pool_(get|set)_dma_addr wrappers.  Can we add a comment in
> v3?

I don't think this is what we want.  Currently drivers call
page_pool_get_dma_addr() on pages that are presumably from the page
pool, but the compiler isn't going to help them out if they just
get the struct page from somewhere random.  They'll get garbage and
presumably crash.

By returning a netmem pointer from page_pool, we help drivers ensure
that they're only passing around memory that was actually allocated
from the page_pool and so they won't get garbage if they pass it to
netmem_get_dma_addr().  The page_pool_get_dma_addr() wrapper is
a temporary measure until we have all the drivers converted to
use netmem alone.

Does that all make sense, or have I misunderstood what you wanted
from a comment?


  parent reply	other threads:[~2023-01-10 18:17 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-05 21:46 [PATCH v2 00/24] Split netmem from struct page Matthew Wilcox (Oracle)
2023-01-05 21:46 ` [PATCH v2 01/24] netmem: Create new type Matthew Wilcox (Oracle)
2023-01-06 13:07   ` Jesper Dangaard Brouer
2023-01-09 17:20   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 02/24] netmem: Add utility functions Matthew Wilcox (Oracle)
2023-01-06  2:24   ` kernel test robot
2023-01-06 20:35     ` Matthew Wilcox
2023-01-06 13:35   ` Jesper Dangaard Brouer
2023-01-05 21:46 ` [PATCH v2 03/24] page_pool: Add netmem_set_dma_addr() and netmem_get_dma_addr() Matthew Wilcox (Oracle)
2023-01-06 13:43   ` Jesper Dangaard Brouer
2023-01-09 17:30   ` Ilias Apalodimas
2023-01-10  9:17     ` Ilias Apalodimas
2023-01-10 18:16       ` Matthew Wilcox
2023-01-10 18:15     ` Matthew Wilcox [this message]
2023-01-05 21:46 ` [PATCH v2 04/24] page_pool: Convert page_pool_release_page() to page_pool_release_netmem() Matthew Wilcox (Oracle)
2023-01-06 13:46   ` Jesper Dangaard Brouer
2023-01-10  9:28   ` Ilias Apalodimas
2023-01-10 18:47     ` Matthew Wilcox
2023-01-11 13:56       ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 05/24] page_pool: Start using netmem in allocation path Matthew Wilcox (Oracle)
2023-01-06  2:34   ` kernel test robot
2023-01-06 13:59   ` Jesper Dangaard Brouer
2023-01-06 15:36     ` Matthew Wilcox
2023-01-10  9:30   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 06/24] page_pool: Convert page_pool_return_page() to page_pool_return_netmem() Matthew Wilcox (Oracle)
2023-01-06 14:10   ` Jesper Dangaard Brouer
2023-01-10  9:39   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 07/24] page_pool: Convert __page_pool_put_page() to __page_pool_put_netmem() Matthew Wilcox (Oracle)
2023-01-06 14:14   ` Jesper Dangaard Brouer
2023-01-10  9:47   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 08/24] page_pool: Convert pp_alloc_cache to contain netmem Matthew Wilcox (Oracle)
2023-01-06 14:18   ` Jesper Dangaard Brouer
2023-01-10  9:58   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 09/24] page_pool: Convert page_pool_defrag_page() to page_pool_defrag_netmem() Matthew Wilcox (Oracle)
2023-01-06 14:29   ` Jesper Dangaard Brouer
2023-01-10 10:27   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 10/24] page_pool: Convert page_pool_put_defragged_page() to netmem Matthew Wilcox (Oracle)
2023-01-06 14:32   ` Jesper Dangaard Brouer
2023-01-10 10:36   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 11/24] page_pool: Convert page_pool_empty_ring() to use netmem Matthew Wilcox (Oracle)
2023-01-06 15:22   ` Jesper Dangaard Brouer
2023-01-10 10:38   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 12/24] page_pool: Convert page_pool_alloc_pages() to page_pool_alloc_netmem() Matthew Wilcox (Oracle)
2023-01-06 15:27   ` Jesper Dangaard Brouer
2023-01-10 10:45   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 13/24] page_pool: Convert page_pool_dma_sync_for_device() to take a netmem Matthew Wilcox (Oracle)
2023-01-06 15:28   ` Jesper Dangaard Brouer
2023-01-10 10:47   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 14/24] page_pool: Convert page_pool_recycle_in_cache() to netmem Matthew Wilcox (Oracle)
2023-01-06 15:29   ` Jesper Dangaard Brouer
2023-01-10 10:48   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 15/24] page_pool: Remove page_pool_defrag_page() Matthew Wilcox (Oracle)
2023-01-06 15:29   ` Jesper Dangaard Brouer
2023-01-10  9:47   ` Ilias Apalodimas
2023-01-10 22:00     ` Matthew Wilcox
2023-01-11 13:58       ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 16/24] page_pool: Use netmem in page_pool_drain_frag() Matthew Wilcox (Oracle)
2023-01-06 15:30   ` Jesper Dangaard Brouer
2023-01-10 11:00   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 17/24] page_pool: Convert page_pool_return_skb_page() to use netmem Matthew Wilcox (Oracle)
2023-01-06 15:49   ` Jesper Dangaard Brouer
2023-01-06 16:53     ` Matthew Wilcox
2023-01-06 20:16       ` Jesper Dangaard Brouer
2023-01-09 18:36         ` Matthew Wilcox
2023-01-10 10:04           ` Jesper Dangaard Brouer
2023-01-05 21:46 ` [PATCH v2 18/24] page_pool: Convert frag_page to frag_nmem Matthew Wilcox (Oracle)
2023-01-06 15:51   ` Jesper Dangaard Brouer
2023-01-10 11:36   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 19/24] xdp: Convert to netmem Matthew Wilcox (Oracle)
2023-01-06 15:53   ` Jesper Dangaard Brouer
2023-01-10 11:50   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 20/24] mm: Remove page pool members from struct page Matthew Wilcox (Oracle)
2023-01-06 15:56   ` Jesper Dangaard Brouer
2023-01-10 11:51   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 21/24] page_pool: Pass a netmem to init_callback() Matthew Wilcox (Oracle)
2023-01-06 16:02   ` Jesper Dangaard Brouer
2023-01-10 11:32   ` Ilias Apalodimas
2023-01-05 21:46 ` [PATCH v2 22/24] net: Add support for netmem in skb_frag Matthew Wilcox (Oracle)
2023-01-05 21:46 ` [PATCH v2 23/24] mvneta: Convert to netmem Matthew Wilcox (Oracle)
2023-01-05 21:46 ` [PATCH v2 24/24] mlx5: " Matthew Wilcox (Oracle)
2023-01-06 16:31   ` Jesper Dangaard Brouer
2023-01-09 11:46     ` Tariq Toukan
2023-01-09 12:27   ` Tariq Toukan
2023-01-06  1:20 ` [PATCH v2 00/24] Split netmem from struct page Jesse Brandeburg

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