Op 11-09-17 om 16:45 schreef Christian König: > Am 11.09.2017 um 15:56 schrieb Maarten Lankhorst: >> Op 11-09-17 om 14:53 schreef Christian König: >>> Am 10.09.2017 um 09:30 schrieb Maarten Lankhorst: >>>> Op 04-09-17 om 21:02 schreef Christian König: >>>>> From: Christian König <christian.koenig at amd.com> >>>>> >>>>> Stop requiring that the src reservation object is locked for this operation. >>>>> >>>>> Signed-off-by: Christian König <christian.koenig at amd.com> >>>>> --- >>>>> drivers/dma-buf/reservation.c | 56 ++++++++++++++++++++++++++++++++----------- >>>>> 1 file changed, 42 insertions(+), 14 deletions(-) >>>>> >>>>> diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c >>>>> index dec3a81..b44d9d7 100644 >>>>> --- a/drivers/dma-buf/reservation.c >>>>> +++ b/drivers/dma-buf/reservation.c >>>>> @@ -266,8 +266,7 @@ EXPORT_SYMBOL(reservation_object_add_excl_fence); >>>>> * @dst: the destination reservation object >>>>> * @src: the source reservation object >>>>> * >>>>> -* Copy all fences from src to dst. Both src->lock as well as dst-lock must be >>>>> -* held. >>>>> +* Copy all fences from src to dst. dst-lock must be held. >>>>> */ >>>>> int reservation_object_copy_fences(struct reservation_object *dst, >>>>> struct reservation_object *src) >>>> Could this be implemented using reservation_object_get_fences_rcu? You're essentially duplicating its functionality. >>> I've considered this as well, but reservation_object_get_fences_rcu() returns an array and here we need an reservation_object_list. >> Doesn't seem too hard, below is the result from fiddling with the allocation function.. >> reservation_object_list is just a list of fences with some junk in front. >> >> Here you go, but only tested with the compiler. O:) >> -----8<----- >> drivers/dma-buf/reservation.c | 192 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------------------------------------------- >> 1 file changed, 109 insertions(+), 83 deletions(-) > > To be honest that looks rather ugly to me for not much gain. > > Additional to that we loose the optimization I've stolen from the wait function. Right now your version does exactly the same as reservation_object_get_fences_rcu, but with a reservation_object_list instead of a fence array. Can't you change reservation_object_get_fences_rcu to return a reservation_object_list? All callsites look like they could be easily converted. So the new patch series would be: 1. Make reservation_object_get_fences_rcu return a reservation_object_list 2. Add optimization 3. Convert reservation_object_copy_fences to use rcu. Cheers, Maarten
