On 12/14/2010 04:11 PM, Jeremy Fitzhardinge wrote:
> On 12/14/2010 06:55 AM, Daniel De Graaf wrote:
>> apply_to_page_range will acquire PTE lock while priv->lock is held, and
>> mn_invl_range_start tries to acquire priv->lock with PTE already held.
>> Fix by not holding priv->lock during the entire map operation.
>
> Is priv->lock needed to protect the contents of map?
>
> J
No, since the map can only be mapped once (checked by map->vma assignment
while the lock is held). The unmap ioctl will return -EBUSY until
an munmap() is called on the area, so it also can't race, and the other
users are only active once the mmap operation completes.
>
>> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
>> ---
>> drivers/xen/gntdev.c | 19 +++++++++----------
>> 1 files changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
>> index a33e443..c582804 100644
>> --- a/drivers/xen/gntdev.c
>> +++ b/drivers/xen/gntdev.c
>> @@ -581,23 +581,22 @@ static int gntdev_mmap(struct file *flip, struct
>> vm_area_struct *vma)
>> if (!(vma->vm_flags & VM_WRITE))
>> map->flags |= GNTMAP_readonly;
>>
>> + spin_unlock(&priv->lock);
>> +
>> err = apply_to_page_range(vma->vm_mm, vma->vm_start,
>> vma->vm_end - vma->vm_start,
>> find_grant_ptes, map);
>> - if (err) {
>> - goto unlock_out;
>> - if (debug)
>> - printk("%s: find_grant_ptes() failure.\n",
>> __FUNCTION__);
>> - }
>> + if (err)
>> + return err;
>>
>> err = map_grant_pages(map);
>> - if (err) {
>> - goto unlock_out;
>> - if (debug)
>> - printk("%s: map_grant_pages() failure.\n",
>> __FUNCTION__);
>> - }
>> + if (err)
>> + return err;
>> +
>> map->is_mapped = 1;
>>
>> + return 0;
>> +
>> unlock_out:
>> spin_unlock(&priv->lock);
>> return err;
>
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home