Linux Virtualization - Mar 2011 - [patch 1/2] xen-gntdev: return -EFAULT on copy_to_user failure

copy_to_user() returns the amount of data remaining to be copied.  We
want to return a negative error code here.  The upper layers just
call WARN_ON() if we return non-zero so this doesn't change the
behavior.  But returning -EFAULT is still cleaner.

Signed-off-by: Dan Carpenter <error27 at gmail.com>

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 017ce60..b0f9e8f 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -273,7 +273,7 @@ static int __unmap_grant_pages(struct grant_map *map, int
offset, int pages)
 				map->vma->vm_start + map->notify.addr;
 			err = copy_to_user(tmp, &err, 1);
 			if (err)
-				return err;
+				return -EFAULT;
 			map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 		} else if (pgno >= offset && pgno < offset + pages) {
 			uint8_t *tmp = kmap(map->pages[pgno]);

On Sat, Mar 19, 2011 at 08:44:34AM +0300, Dan Carpenter
wrote:
> copy_to_user() returns the amount of data remaining to be copied.  We
> want to return a negative error code here.  The upper layers just
> call WARN_ON() if we return non-zero so this doesn't change the
> behavior.  But returning -EFAULT is still cleaner.
Thank you. Will put it on rc1 train.
> 
> Signed-off-by: Dan Carpenter <error27 at gmail.com>
> 
> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index 017ce60..b0f9e8f 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -273,7 +273,7 @@ static int __unmap_grant_pages(struct grant_map *map,
int offset, int pages)
>  				map->vma->vm_start + map->notify.addr;
>  			err = copy_to_user(tmp, &err, 1);
>  			if (err)
> -				return err;
> +				return -EFAULT;
>  			map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
>  		} else if (pgno >= offset && pgno < offset + pages) {
>  			uint8_t *tmp = kmap(map->pages[pgno]);
> 
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