Re: [PATCH net-next v15 03/14] netdev: support binding dma-buf to netdevice

[Paolo Abeni <pabeni@redhat.com>]

On Tue, 2024-07-02 at 13:08 +0200, Paolo Abeni wrote:
> On Fri, 2024-06-28 at 00:32 +0000, Mina Almasry wrote:
> > +int net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
> > +			   struct net_devmem_dmabuf_binding **out)
> > +{
> > +	struct net_devmem_dmabuf_binding *binding;
> > +	static u32 id_alloc_next;
> > +	struct scatterlist *sg;
> > +	struct dma_buf *dmabuf;
> > +	unsigned int sg_idx, i;
> > +	unsigned long virtual;
> > +	int err;
> > +
> > +	dmabuf = dma_buf_get(dmabuf_fd);
> > +	if (IS_ERR(dmabuf))
> > +		return -EBADFD;
> > +
> > +	binding = kzalloc_node(sizeof(*binding), GFP_KERNEL,
> > +			       dev_to_node(&dev->dev));
> > +	if (!binding) {
> > +		err = -ENOMEM;
> > +		goto err_put_dmabuf;
> > +	}
> > +
> > +	binding->dev = dev;
> > +
> > +	err = xa_alloc_cyclic(&net_devmem_dmabuf_bindings, &binding->id,
> > +			      binding, xa_limit_32b, &id_alloc_next,
> > +			      GFP_KERNEL);
> > +	if (err < 0)
> > +		goto err_free_binding;
> > +
> > +	xa_init_flags(&binding->bound_rxq_list, XA_FLAGS_ALLOC);
> > +
> > +	refcount_set(&binding->ref, 1);
> > +
> > +	binding->dmabuf = dmabuf;
> > +
> > +	binding->attachment = dma_buf_attach(binding->dmabuf, dev->dev.parent);
> > +	if (IS_ERR(binding->attachment)) {
> > +		err = PTR_ERR(binding->attachment);
> > +		goto err_free_id;
> > +	}
> > +
> > +	binding->sgt =
> > +		dma_buf_map_attachment(binding->attachment, DMA_FROM_DEVICE);
> > +	if (IS_ERR(binding->sgt)) {
> > +		err = PTR_ERR(binding->sgt);
> > +		goto err_detach;
> > +	}
> > +
> > +	/* For simplicity we expect to make PAGE_SIZE allocations, but the
> > +	 * binding can be much more flexible than that. We may be able to
> > +	 * allocate MTU sized chunks here. Leave that for future work...
> > +	 */
> > +	binding->chunk_pool =
> > +		gen_pool_create(PAGE_SHIFT, dev_to_node(&dev->dev));
> > +	if (!binding->chunk_pool) {
> > +		err = -ENOMEM;
> > +		goto err_unmap;
> > +	}
> > +
> > +	virtual = 0;
> > +	for_each_sgtable_dma_sg(binding->sgt, sg, sg_idx) {
> > +		dma_addr_t dma_addr = sg_dma_address(sg);
> > +		struct dmabuf_genpool_chunk_owner *owner;
> > +		size_t len = sg_dma_len(sg);
> > +		struct net_iov *niov;
> > +
> > +		owner = kzalloc_node(sizeof(*owner), GFP_KERNEL,
> > +				     dev_to_node(&dev->dev));
> 
> I'm sorry for not catching this earlier, but it looks like the above
> allocation lacks a NULL check.

FTR, given the size of the series, the number of iterations already
done and the issue not preventing the functionality, I agree to merge
the series as-is, and handle this with a follow-up.

Thanks,

Paolo