Hi Christian,
On 8/9 星期二 17:08, Christian König wrote:
Hi Jeffy,
Am 09.08.22 um 09:55 schrieb Christian König:
[SNIP]
So we are allowing GEM object to have multiple handles, and GEM
object could have at most one dma-buf, doesn't that means that
dma-buf could map to multiple handles?
No, at least not for the same GEM file private. That's the reason
why the rb is indexed by the dma_buf object and not the handle.
In other words the rb is so that you have exactly one handle for
each dma_buf in each file private.
I don't think so, because if user get multiple handles for the same
GEM obj and use drm_gem_prime_handle_to_fd() for those handles
Mhm, that works? This is illegal and should have been prevented somehow.
At least I see the problem now. I'm just not sure how to fix it.
Your v2 patch indeed prevents leakage of the drm_prime_member for the
additional handles, but those shouldn't have been added in the first place.
The issue is that with this we make it unpredictable which handle is
returned. E.g. if we have handle 2,5,7 it can be that because of
re-balancing the tree sometimes 2 and sometimes 5 is returned.
Maybe cache the latest returned handle in the obj(after
drm_gem_prime_fd_to_handle), and clear it when that handle been deleted
in drm_gem_handle_delete()?
Something like:
drm_gem_prime_fd_to_handle
handle = drm_prime_lookup_buf_handle(buf)
obj = obj_from_handle(handle)
if !obj->primary_handle
obj->primary_handle = handle
return obj->primary_handle
Or maybe limit GEM obj with a single lifetime handle?
That's not really a good idea and breaks a couple of assumptions as far
as I know.
Ideas?
Thanks,
Christian.
