On 12/14/2010 06:55 AM, Daniel De Graaf wrote:
> Because there is no limitation on how many times a user can open a
> given device file, an per-file-description limit on the number of
> pages granted offers little to no benefit. Change to a global limit
> and remove the ioctl() as the parameter can now be changed via sysfs.
Does anyone use this ioctl? Wouldn't it be safer to replace it with a
no-op version?
J
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
> drivers/xen/gntdev.c | 48 ++++++++++++++----------------------------------
> 1 files changed, 14 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index c582804..62639af 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -44,13 +44,12 @@ MODULE_DESCRIPTION("User-space granted page access
> driver");
>
> static int debug = 0;
> module_param(debug, int, 0644);
> -static int limit = 1024;
> +static int limit = 1024*1024;
> module_param(limit, int, 0644);
> +static atomic_t pages_mapped = ATOMIC_INIT(0);
>
> struct gntdev_priv {
> struct list_head maps;
> - uint32_t used;
> - uint32_t limit;
> spinlock_t lock;
> struct mm_struct *mm;
> struct mmu_notifier mn;
> @@ -76,8 +75,8 @@ static void gntdev_print_maps(struct gntdev_priv *priv,
> {
> struct grant_map *map;
>
> - printk("%s: maps list (priv %p, usage %d/%d)\n",
> - __FUNCTION__, priv, priv->used, priv->limit);
> + printk("%s: maps list (priv %p)\n",
> + __FUNCTION__, priv);
> list_for_each_entry(map, &priv->maps, next)
> printk(" index %2d, count %2d %s\n",
> map->index, map->count,
> @@ -104,9 +103,6 @@ static struct grant_map *gntdev_alloc_map(struct
> gntdev_priv *priv, int count)
> add->count = count;
> add->priv = priv;
>
> - if (add->count + priv->used > priv->limit)
> - goto err;
> -
> return add;
>
> err:
> @@ -131,7 +127,6 @@ static void gntdev_add_map(struct gntdev_priv *priv,
> struct grant_map *add)
> list_add_tail(&add->next, &priv->maps);
>
> done:
> - priv->used += add->count;
> if (debug)
> gntdev_print_maps(priv, "[new]", add->index);
> }
> @@ -178,7 +173,7 @@ static int gntdev_del_map(struct grant_map *map)
> if (map->unmap_ops[i].handle)
> return -EBUSY;
>
> - map->priv->used -= map->count;
> + atomic_sub(map->count, &pages_mapped);
> list_del(&map->next);
> return 0;
> }
> @@ -360,7 +355,6 @@ static int gntdev_open(struct inode *inode, struct file
> *flip)
>
> INIT_LIST_HEAD(&priv->maps);
> spin_lock_init(&priv->lock);
> - priv->limit = limit;
>
> priv->mm = get_task_mm(current);
> if (!priv->mm) {
> @@ -416,19 +410,26 @@ static long gntdev_ioctl_map_grant_ref(struct
> gntdev_priv *priv,
> op.count);
> if (unlikely(op.count <= 0))
> return -EINVAL;
> - if (unlikely(op.count > priv->limit))
> - return -EINVAL;
>
> err = -ENOMEM;
> map = gntdev_alloc_map(priv, op.count);
> if (!map)
> return err;
> +
> if (copy_from_user(map->grants, &u->refs,
> sizeof(map->grants[0]) * op.count) != 0) {
> gntdev_free_map(map);
> return err;
> }
>
> + if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit))
> + {
> + if (debug)
> + printk("%s: can't map: over limit\n", __FUNCTION__);
> + gntdev_free_map(map);
> + return err;
> + }
> +
> spin_lock(&priv->lock);
> gntdev_add_map(priv, map);
> op.index = map->index << PAGE_SHIFT;
> @@ -495,24 +496,6 @@ static long gntdev_ioctl_get_offset_for_vaddr(struct
> gntdev_priv *priv,
> return 0;
> }
>
> -static long gntdev_ioctl_set_max_grants(struct gntdev_priv *priv,
> - struct ioctl_gntdev_set_max_grants
> __user *u)
> -{
> - struct ioctl_gntdev_set_max_grants op;
> -
> - if (copy_from_user(&op, u, sizeof(op)) != 0)
> - return -EFAULT;
> - if (debug)
> - printk("%s: priv %p, limit %d\n", __FUNCTION__, priv, op.count);
> - if (op.count > limit)
> - return -EINVAL;
> -
> - spin_lock(&priv->lock);
> - priv->limit = op.count;
> - spin_unlock(&priv->lock);
> - return 0;
> -}
> -
> static long gntdev_ioctl(struct file *flip,
> unsigned int cmd, unsigned long arg)
> {
> @@ -529,9 +512,6 @@ static long gntdev_ioctl(struct file *flip,
> case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
> return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
>
> - case IOCTL_GNTDEV_SET_MAX_GRANTS:
> - return gntdev_ioctl_set_max_grants(priv, ptr);
> -
> default:
> if (debug)
> printk("%s: priv %p, unknown cmd %x\n",
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