Re: [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock

[Michel Lespinasse]

On Mon, May 18, 2020 at 03:45:22PM +0200, Laurent Dufour wrote:
> Le 24/04/2020 à 03:39, Michel Lespinasse a écrit :
> > Rename the mmap_sem field to mmap_lock. Any new uses of this lock
> > should now go through the new mmap locking api. The mmap_lock is
> > still implemented as a rwsem, though this could change in the future.
> > 
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> > index dc9ef302f517..701f3995f621 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
> > @@ -661,7 +661,7 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj)
> >   	struct etnaviv_gem_userptr *userptr = &etnaviv_obj->userptr;
> >   	int ret, pinned = 0, npages = etnaviv_obj->base.size >> PAGE_SHIFT;
> > -	might_lock_read(&current->mm->mmap_sem);
> > +	might_lock_read(&current->mm->mmap_lock);
> 
> Why not a mm_might_lock_read() new API to hide the mmap_lock, and add it to
> the previous patch?

I'm not sure why this is needed - we may rework the lock to be
something else than rwsem, but might_lock_read should still apply to
it and make sense ? I'm not sure what the extra API would bring...

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.