Hi Stefano,
On 03/06/2017 08:01 PM, Stefano Stabellini wrote:
+static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
+ struct xen_9pfs_dataring *ring)
+{
+ int i;
+ int ret = -ENOMEM;
+
+ init_waitqueue_head(&ring->wq);
+ spin_lock_init(&ring->lock);
+ INIT_WORK(&ring->work, p9_xen_response);
+
+ ring->intf = (struct xen_9pfs_data_intf *) __get_free_page(GFP_KERNEL |
__GFP_ZERO);
+ if (!ring->intf)
+ goto error;
+ memset(ring->intf, 0, XEN_PAGE_SIZE);
+ ring->bytes = (void*)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
XEN_9PFS_RING_ORDER);
The ring order will be in term of Xen page size and not Linux. So you
are going to allocate much more memory than expected on 64KB kernel.
+ if (ring->bytes == NULL)
+ goto error;
+ for (i = 0; i < (1 << XEN_9PFS_RING_ORDER); i++)
+ ring->intf->ref[i] = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->bytes) + i), 0);.
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
Also, this is not going to work on 64K kernel because you will grant
access to noncontiguous memory (e.g 0-4K, 64K-68K,...).
We have various helper to break-down the page for you, see
gnttab_for_one_grant, gnttab_foreach_grant, gnttab_count_grant,
xen_for_each_gfn (though this one it is internal to xlate_mmu.c so far)
Please use them to avoid any further.
+ ring->ref = gnttab_grant_foreign_access(dev->otherend_id,
pfn_to_gfn(virt_to_pfn((void*)ring->intf)), 0);
Please use virt_to_gfn rather than pfn_to_gfn(virt_to_pfn).
+ ring->ring.in = ring->bytes;
+ ring->ring.out = ring->bytes + XEN_9PFS_RING_SIZE;
+
+ ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
+ if (ret)
+ goto error;
+ ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
xen_9pfs_front_event_handler,
+ 0, "xen_9pfs-frontend", ring);
+ if (ring->irq < 0) {
+ xenbus_free_evtchn(dev, ring->evtchn);
+ ret = ring->irq;
+ goto error;
+ }
return 0;
+
+error:
+ if (ring->intf != NULL)
+ kfree(ring->intf);
+ if (ring->bytes != NULL)
+ kfree(ring->bytes);
+ return ret;
}
Cheers,
--
Julien Grall
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