On Tue, Oct 18, 2016 at 02:54:25PM +0200, Jan Kara wrote:
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages, int write, int force, struct page **pages, struct vm_area_struct **vmas); long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
int write, int force, struct page **pages, int *locked);
unsigned int gup_flags, struct page **pages, int *locked);Hum, the prototype is inconsistent with e.g. __get_user_pages_unlocked() where gup_flags come after **pages argument. Actually it makes more sense to have it before **pages so that input arguments come first and output arguments second but I don't care that much. But it definitely should be consistent...
It was difficult to decide quite how to arrange parameters as there was inconsitency with regards to parameter ordering already - for example __get_user_pages() places its flags argument before pages whereas, as you note, __get_user_pages_unlocked() puts them afterwards.
I ended up compromising by trying to match the existing ordering of the function as much as I could by replacing write, force pairs with gup_flags in the same location (with the exception of get_user_pages_unlocked() which I felt should match __get_user_pages_unlocked() in signature) or if there was already a gup_flags parameter as in the case of __get_user_pages_unlocked() I simply removed the write, force pair and left the flags as the last parameter.
I am happy to rearrange parameters as needed, however I am not sure if it'd be worthwhile for me to do so (I am keen to try to avoid adding too much noise here :)
If we were to rearrange parameters for consistency I'd suggest adjusting __get_user_pages_unlocked() to put gup_flags before pages and do the same with get_user_pages_unlocked(), let me know what you think.