> -----Original Message-----
> From: Jason Gunthorpe <j...@ziepe.ca>
> Sent: Thursday, November 12, 2020 4:31 PM
> To: Xiong, Jianxin <jianxin.xi...@intel.com>
> Cc: linux-r...@vger.kernel.org; dri-devel@lists.freedesktop.org; Doug Ledford
> <dledf...@redhat.com>; Leon Romanovsky
> <l...@kernel.org>; Sumit Semwal <sumit.sem...@linaro.org>; Christian Koenig
> <christian.koe...@amd.com>; Vetter, Daniel
> <daniel.vet...@intel.com>
> Subject: Re: [PATCH v10 1/6] RDMA/umem: Support importing dma-buf as user
> memory region
>
> On Tue, Nov 10, 2020 at 01:41:12PM -0800, Jianxin Xiong wrote:
> > +struct ib_umem *ib_umem_dmabuf_get(struct ib_device *device,
> > + unsigned long offset, size_t size,
> > + int fd, int access,
> > + const struct dma_buf_attach_ops *ops) {
> > + struct dma_buf *dmabuf;
> > + struct ib_umem_dmabuf *umem_dmabuf;
> > + struct ib_umem *umem;
> > + unsigned long end;
> > + long ret;
> > +
> > + if (check_add_overflow(offset, (unsigned long)size, &end))
> > + return ERR_PTR(-EINVAL);
> > +
> > + if (unlikely(PAGE_ALIGN(end) < PAGE_SIZE))
> > + return ERR_PTR(-EINVAL);
>
> This is weird, what does it do?
This sequence is modeled after the following code from ib_umem_init_odp():
if (check_add_overflow(umem_odp->umem.address,
(unsigned long)umem_odp->umem.length,
&end))
return -EOVERFLOW;
end = ALIGN(end, page_size);
if (unlikely(end < page_size))
return -EOVERFLOW;
The weird part seems to be checking if 'end' is 0, but that should have been
covered
by check_add_overflow() already.
>
> > +
> > + if (unlikely(!ops || !ops->move_notify))
> > + return ERR_PTR(-EINVAL);
> > +
> > + umem_dmabuf = kzalloc(sizeof(*umem_dmabuf), GFP_KERNEL);
> > + if (!umem_dmabuf)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + umem = &umem_dmabuf->umem;
> > + umem->ibdev = device;
> > + umem->length = size;
> > + umem->address = offset;
> > + umem->writable = ib_access_writable(access);
> > + umem->is_dmabuf = 1;
> > +
> > + if (unlikely(!ib_umem_num_pages(umem))) {
> > + ret = -EINVAL;
> > + goto out_free_umem;
> > + }
> > +
> > + dmabuf = dma_buf_get(fd);
> > + if (IS_ERR(dmabuf)) {
> > + ret = PTR_ERR(dmabuf);
> > + goto out_free_umem;
> > + }
> > +
> > + if (dmabuf->size < offset + size) {
> > + ret = -EINVAL;
> > + goto out_release_dmabuf;
>
> offset + size == end, already computed, in fact move this above the kzalloc
>
> Jason
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