Questions about TTM buffer object maping

[Jerome Glisse]

On Thu, Jul 11, 2013 at 5:43 PM, Jean-Sébastien Pédron
<jean-sebastien.pedron at dumbbell.fr> wrote:
> Hi,
>
> Thank you Jérôme and Daniel for your input, that's really helpful!
>
> I have another question: in ttm_bo_mmap(), a reference to the buffer object
> is acquired at the beginning of the function. Another reference is acquired
> in ttm_bo_vm_open() (released in ttm_bo_vm_close()).
>
> But where is the first reference released?
>
> --
> Jean-Sébastien Pédron

the ttm_bo_vm_open is not call on first time a vma is mmap, ie when
userspace do mmap it call driver
mmap callback which call ttm_bo_mmap but ttm_bo_vm_open is never call.
If the same process or
another process mmap the same area or subarea the ttm_bo_vm_open is
call. Then on each unmap
ttm_bo_vm_close is call.

Cheers,
Jerome