On Mon, 2011-03-07 at 20:18 +0000, Daniel De Graaf wrote:
> The only time when granted pages need to be treated specially is when
> using Xen's PTE modification for grant mappings owned by another domain
> (that is, only gntdev on PV guests). Otherwise, the area does not
> require VM_DONTCOPY and VM_PFNMAP, since it can be accessed just like
> any other page of RAM.
>
> Since the vm_operations_struct close operations decrement reference
> counts, a corresponding open function that increments them is required
> now that it is possible to have multiple references to a single area.
>
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
Looks good, thanks.
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
> drivers/xen/gntalloc.c | 14 ++++++++++++--
> drivers/xen/gntdev.c | 16 ++++++++++++++--
> 2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
> index a7ffdfe..f6832f4 100644
> --- a/drivers/xen/gntalloc.c
> +++ b/drivers/xen/gntalloc.c
> @@ -427,6 +427,17 @@ static long gntalloc_ioctl(struct file *filp, unsigned
> int cmd,
> return 0;
> }
>
> +static void gntalloc_vma_open(struct vm_area_struct *vma)
> +{
> + struct gntalloc_gref *gref = vma->vm_private_data;
> + if (!gref)
> + return;
> +
> + spin_lock(&gref_lock);
> + gref->users++;
> + spin_unlock(&gref_lock);
> +}
> +
> static void gntalloc_vma_close(struct vm_area_struct *vma)
> {
> struct gntalloc_gref *gref = vma->vm_private_data;
> @@ -441,6 +452,7 @@ static void gntalloc_vma_close(struct vm_area_struct *vma)
> }
>
> static struct vm_operations_struct gntalloc_vmops = {
> + .open = gntalloc_vma_open,
> .close = gntalloc_vma_close,
> };
>
> @@ -471,8 +483,6 @@ static int gntalloc_mmap(struct file *filp, struct
> vm_area_struct *vma)
> vma->vm_private_data = gref;
>
> vma->vm_flags |= VM_RESERVED;
> - vma->vm_flags |= VM_DONTCOPY;
> - vma->vm_flags |= VM_PFNMAP | VM_PFN_AT_MMAP;
>
> vma->vm_ops = &gntalloc_vmops;
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index 2faf797..69c787a 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -334,17 +334,26 @@ static int unmap_grant_pages(struct grant_map *map, int
> offset, int pages)
>
> /* ------------------------------------------------------------------ */
>
> +static void gntdev_vma_open(struct vm_area_struct *vma)
> +{
> + struct grant_map *map = vma->vm_private_data;
> +
> + pr_debug("gntdev_vma_open %p\n", vma);
> + atomic_inc(&map->users);
> +}
> +
> static void gntdev_vma_close(struct vm_area_struct *vma)
> {
> struct grant_map *map = vma->vm_private_data;
>
> - pr_debug("close %p\n", vma);
> + pr_debug("gntdev_vma_close %p\n", vma);
> map->vma = NULL;
> vma->vm_private_data = NULL;
> gntdev_put_map(map);
> }
>
> static struct vm_operations_struct gntdev_vmops = {
> + .open = gntdev_vma_open,
> .close = gntdev_vma_close,
> };
>
> @@ -656,7 +665,10 @@ static int gntdev_mmap(struct file *flip, struct
> vm_area_struct *vma)
>
> vma->vm_ops = &gntdev_vmops;
>
> - vma->vm_flags |= VM_RESERVED|VM_DONTCOPY|VM_DONTEXPAND|VM_PFNMAP;
> + vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
> +
> + if (use_ptemod)
> + vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
>
> vma->vm_private_data = map;
>
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