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

[Laurent Dufour]

Le 19/05/2020 Ã 15:10, Michel Lespinasse a ÃcritÂ:
> On Mon, May 18, 2020 at 03:45:22PM +0200, Laurent Dufour wrote:
> > Le 24/04/2020 Ã 03:39, Michel Lespinasse a ÃcritÂ:
> > > 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...

I guess at one time the API would become might_lock_read_a_range(), isn't it?
Furthermore this would hiding the lock's name which the goal of this series.