From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe JAILLET Date: Sat, 11 Jul 2020 13:38:37 +0000 Subject: Re: [PATCH] staging: comedi: s626: Remove pci-dma-compat wrapper APIs. Message-Id: <6f701731-d0af-1bd5-5854-42f0ba39ed35@wanadoo.fr> List-Id: References: <20200711123533.GA15038@blackclown> In-Reply-To: <20200711123533.GA15038@blackclown> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Suraj Upadhyay , gregkh@linuxfoundation.org, abbotti@mev.co.uk, hsweeten@visionengravers.com Cc: devel@driverdev.osuosl.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Le 11/07/2020 =E0 14:35, Suraj Upadhyay a =E9crit=A0: > The legacy API wrappers in include/linux/pci-dma-compat.h > should go away as it creates unnecessary midlayering > for include/linux/dma-mapping.h APIs, instead use dma-mapping.h > APIs directly. > > The patch has been generated with the coccinelle script below > and compile-tested. > > [...] > @@ expression E1, E2, E3; @@ > - pci_alloc_consistent(E1, E2, E3) > + dma_alloc_coherent(&E1->dev, E2, E3, GFP_ATOMIC) > > @@ expression E1, E2, E3; @@ > - pci_zalloc_consistent(E1, E2, E3) > + dma_alloc_coherent(&E1->dev, E2, E3, GFP_ATOMIC) This is the tricky part of this kind of cleanup, see below. GFP_ATOMIC can't be wrong because it is was exactly what was done with=20 the pci_ function. However, most of the time, it can safely be replaced by GFP_KERNEL which=20 gives more opportunities to the memory allocator. > [...] > diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/come= di/drivers/s626.c > index 084a8e7b9fc2..c159416662fd 100644 > --- a/drivers/staging/comedi/drivers/s626.c > +++ b/drivers/staging/comedi/drivers/s626.c > @@ -2130,13 +2130,15 @@ static int s626_allocate_dma_buffers(struct comed= i_device *dev) > void *addr; > dma_addr_t appdma; > =20 > - addr =3D pci_alloc_consistent(pcidev, S626_DMABUF_SIZE, &appdma); > + addr =3D dma_alloc_coherent(&pcidev->dev, S626_DMABUF_SIZE, &appdma, > + GFP_ATOMIC); > if (!addr) > return -ENOMEM; > devpriv->ana_buf.logical_base =3D addr; > devpriv->ana_buf.physical_base =3D appdma; > =20 > - addr =3D pci_alloc_consistent(pcidev, S626_DMABUF_SIZE, &appdma); > + addr =3D dma_alloc_coherent(&pcidev->dev, S626_DMABUF_SIZE, &appdma, > + GFP_ATOMIC); > if (!addr) > return -ENOMEM; > devpriv->rps_buf.logical_base =3D addr; 's626_allocate_dma_buffers()' is only called from 's626_auto_attach()'. In this function, around the call to 's626_allocate_dma_buffers()', you=20 can see: =A0 - a few lines before, a call to 'comedi_alloc_devpriv()' =A0 - a few lines after, a call to 'comedi_alloc_subdevices()' These 2 functions make some memory allocation using GFP_KERNEL. So it is likely that using GFP_KERNEL in your proposal is also valid. Just my 2c. CJ