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Message-ID: <20241025132054.GE6956@nvidia.com>
Date: Fri, 25 Oct 2024 10:20:54 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Alexey Kardashevskiy <aik@....com>
Cc: Nicolin Chen <nicolinc@...dia.com>, kevin.tian@...el.com,
will@...nel.org, joro@...tes.org, suravee.suthikulpanit@....com,
robin.murphy@....com, dwmw2@...radead.org, baolu.lu@...ux.intel.com,
shuah@...nel.org, linux-kernel@...r.kernel.org,
iommu@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
linux-kselftest@...r.kernel.org, eric.auger@...hat.com,
jean-philippe@...aro.org, mdf@...nel.org, mshavit@...gle.com,
shameerali.kolothum.thodi@...wei.com, smostafa@...gle.com,
yi.l.liu@...el.com, zhangfei.gao@...aro.org,
patches@...ts.linux.dev
Subject: Re: [PATCH v4 01/14] iommufd/viommu: Introduce IOMMUFD_OBJ_VDEVICE
and its related struct
On Fri, Oct 25, 2024 at 06:53:01PM +1100, Alexey Kardashevskiy wrote:
> > +#define iommufd_vdevice_alloc(ictx, drv_struct, member) \
> > + ({ \
> > + static_assert( \
> > + __same_type(struct iommufd_vdevice, \
> > + ((struct drv_struct *)NULL)->member)); \
> > + static_assert(offsetof(struct drv_struct, member.obj) == 0); \
> > + container_of(_iommufd_object_alloc(ictx, \
> > + sizeof(struct drv_struct), \
> > + IOMMUFD_OBJ_VDEVICE), \
> > + struct drv_struct, member.obj); \
> > + })
> > #endif
>
> A nit: it hurts eyes to read:
>
> mock_vdev = iommufd_vdevice_alloc(viommu->ictx, mock_vdevice, core);
>
> vs.
>
> mock_vdev = iommufd_vdevice_alloc(viommu->ictx, struct mock_vdevice, core);
>
> as for the former I go searching for a "mock_vdevice" variable and for the
> latter it is clear it is 1) a macro 2) which does some type checking.
>
> also, it makes it impossible to pass things like typeof(..) or a type from
> typedef. Thanks,
Makes sense to me
And the container_of() should not be used in these macros, the point
was to avoid it to make the PTR_ERR behavior cleraer. Just put a force
type cast
Jason
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