[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 4/7] xen/9pfs: connect to the backend
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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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