linux-kernel - Re: [PATCH] forcedeth: switch from 'pci_' to 'dma

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Message-ID: <CAD=hENcZ=D58ZJY5iakbJ3eGmkP3EzUD2YvO0F9oBzZMc=YD4g@mail.gmail.com>
Date:   Mon, 23 Aug 2021 13:04:00 +0800
From:   Zhu Yanjun <zyjzyj2000@...il.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Rain River <rain.1986.08.12@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] forcedeth: switch from 'pci_' to 'dma_' API

On Mon, Aug 23, 2021 at 12:35 PM Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
>
> Le 23/08/2021 à 04:39, Zhu Yanjun a écrit :
> > On Sun, Aug 22, 2021 at 3:09 PM Christophe JAILLET
> > <christophe.jaillet@...adoo.fr> wrote:
> >>
> >> The wrappers in include/linux/pci-dma-compat.h should go away.
> >>
> >> The patch has been generated with the coccinelle script below.
> >>
> >> It has been hand modified to use 'dma_set_mask_and_coherent()' instead of
> >> 'pci_set_dma_mask()/pci_set_consistent_dma_mask()' when applicable.
> >> This is less verbose.
> >>
> >> It has been compile tested.
> >>
> >>
> >> @@
> >> @@
> >> -    PCI_DMA_BIDIRECTIONAL
> >> +    DMA_BIDIRECTIONAL
> >>
> >> @@
> >> @@
> >> -    PCI_DMA_TODEVICE
> >> +    DMA_TO_DEVICE
> >>
> >> @@
> >> @@
> >> -    PCI_DMA_FROMDEVICE
> >> +    DMA_FROM_DEVICE
> >>
> >> @@
> >> @@
> >> -    PCI_DMA_NONE
> >> +    DMA_NONE
> >>
> >> @@
> >> expression e1, e2, e3;
> >> @@
> >> -    pci_alloc_consistent(e1, e2, e3)
> >> +    dma_alloc_coherent(&e1->dev, e2, e3, GFP_)
> >>
> >> @@
> >> expression e1, e2, e3;
> >> @@
> >> -    pci_zalloc_consistent(e1, e2, e3)
> >> +    dma_alloc_coherent(&e1->dev, e2, e3, GFP_)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_free_consistent(e1, e2, e3, e4)
> >> +    dma_free_coherent(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_map_single(e1, e2, e3, e4)
> >> +    dma_map_single(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_unmap_single(e1, e2, e3, e4)
> >> +    dma_unmap_single(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4, e5;
> >> @@
> >> -    pci_map_page(e1, e2, e3, e4, e5)
> >> +    dma_map_page(&e1->dev, e2, e3, e4, e5)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_unmap_page(e1, e2, e3, e4)
> >> +    dma_unmap_page(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_map_sg(e1, e2, e3, e4)
> >> +    dma_map_sg(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_unmap_sg(e1, e2, e3, e4)
> >> +    dma_unmap_sg(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_dma_sync_single_for_cpu(e1, e2, e3, e4)
> >> +    dma_sync_single_for_cpu(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_dma_sync_single_for_device(e1, e2, e3, e4)
> >> +    dma_sync_single_for_device(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_dma_sync_sg_for_cpu(e1, e2, e3, e4)
> >> +    dma_sync_sg_for_cpu(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2, e3, e4;
> >> @@
> >> -    pci_dma_sync_sg_for_device(e1, e2, e3, e4)
> >> +    dma_sync_sg_for_device(&e1->dev, e2, e3, e4)
> >>
> >> @@
> >> expression e1, e2;
> >> @@
> >> -    pci_dma_mapping_error(e1, e2)
> >> +    dma_mapping_error(&e1->dev, e2)
> >>
> >> @@
> >> expression e1, e2;
> >> @@
> >> -    pci_set_dma_mask(e1, e2)
> >> +    dma_set_mask(&e1->dev, e2)
> >>
> >> @@
> >> expression e1, e2;
> >> @@
> >> -    pci_set_consistent_dma_mask(e1, e2)
> >> +    dma_set_coherent_mask(&e1->dev, e2)
> >>
> >> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> >> ---
> >> If needed, see post from Christoph Hellwig on the kernel-janitors ML:
> >>     https://marc.info/?l=kernel-janitors&m=158745678307186&w=4
> >> ---
> >>   drivers/net/ethernet/nvidia/forcedeth.c | 6 +-----
> >>   1 file changed, 1 insertion(+), 5 deletions(-)
> >>
> >> diff --git a/drivers/net/ethernet/nvidia/forcedeth.c b/drivers/net/ethernet/nvidia/forcedeth.c
> >> index 8724d6a9ed02..ef3fb4cc90af 100644
> >> --- a/drivers/net/ethernet/nvidia/forcedeth.c
> >> +++ b/drivers/net/ethernet/nvidia/forcedeth.c
> >> @@ -5782,15 +5782,11 @@ static int nv_probe(struct pci_dev *pci_dev, const struct pci_device_id *id)
> >>                  np->desc_ver = DESC_VER_3;
> >>                  np->txrxctl_bits = NVREG_TXRXCTL_DESC_3;
> >>                  if (dma_64bit) {
> >> -                       if (pci_set_dma_mask(pci_dev, DMA_BIT_MASK(39)))
> >> +                       if (dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(39)))
> >>                                  dev_info(&pci_dev->dev,
> >>                                           "64-bit DMA failed, using 32-bit addressing\n");
> >>                          else
> >>                                  dev->features |= NETIF_F_HIGHDMA;
> >> -                       if (pci_set_consistent_dma_mask(pci_dev, DMA_BIT_MASK(39))) {
> >> -                               dev_info(&pci_dev->dev,
> >> -                                        "64-bit DMA (consistent) failed, using 32-bit ring buffers\n");
> >> -                       }
> >
> >  From the commit log, "pci_set_consistent_dma_mask(e1, e2)" should be
> > replaced by "dma_set_coherent_mask(&e1->dev, e2)".
> > But in this snippet,  "pci_set_consistent_dma_mask(e1, e2)" is not
> > replaced by "dma_set_coherent_mask(&e1->dev, e2)".
> >
> > Why?
>
> Hi,
> in the commit log I said that:
>      The patch has been generated with the coccinelle script below.
>
>      It has been hand modified to use 'dma_set_mask_and_coherent()'
>      instead of 'pci_set_dma_mask()/pci_set_consistent_dma_mask()' when
>      applicable.
>      This is less verbose.

Got it, thanks!

Reviewed-by: Zhu Yanjun <zyjzyj2000@...il.com>

Zhu Yanjun

>
> When I started this task proposed by Christoph Hellwig ([1]), their were
> 150 files using using 'pci_set_dma_mask()' ([2]). Many of them were good
> candidate for using 'dma_set_mask_and_coherent()' but this
> transformation can not easily be done by coccinelle because it depends
> on the way the code has been written.
>
> So, I decided to hand modify and include the transformation in the many
> patches have sent to remove this deprecated API.
> Up to now, it has never been an issue.
>
> I *DO* know that it should have been a 2 steps process but this clean-up
> was too big for me (i.e. 150 files) and doing the job twice was
> discouraging.
>
> My first motivation was to remove the deprecated API. Simplifying code
> and using 'dma_set_mask_and_coherent()' when applicable was just a bonus.
>
> So, if desired, I can send a v2 without the additional transformation
> but I won't send 2 patches for that. The 'dma_set_mask_and_coherent()'
> transformation would be left apart, for whoever feels like cleaning it.
>
> CJ
>
>
> [1]: https://marc.info/?l=kernel-janitors&m=158745678307186&w=4
> [2]: https://elixir.bootlin.com/linux/v5.8/A/ident/pci_set_dma_mask
>
>
> >
> > Zhu Yanjun
> >
> >
> >>                  }
> >>          } else if (id->driver_data & DEV_HAS_LARGEDESC) {
> >>                  /* packet format 2: supports jumbo frames */
> >> --
> >> 2.30.2
> >>
> >
>