>
> - if (check->context == fence->context ||
> + if ((check->context == fence->context &&
> + dma_fence_is_later(fence, check)) ||
We still need do more for !dma_fence_is_later(fence, check) case, in which, we will don't need add new fence to resv slot.
if ((check->context == fence->context) && dma_fence_is_later(fence, check))
fobj->shared_count = j;
RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
fobj->shared_count++;
} else {
dma_fence_put(fence);
}
No you cannot do that, check is changed and not the one you want,
Besides, we don't need to consider the case you mentioned, take only one fence in obj->staged for example:
You add a fence whose context is equal to this fence (check), so current logic will put this check into fobj->shared[++j], so in the end
Obj->fence will point to fobj, and original old would be rcu_kfree()
No additional action actually needed...
/Monk
-----Original Message-----
From: Zhou, David(ChunMing)
Sent: 2018年3月6日 12:25
To: Liu, Monk <Monk.Liu@xxxxxxx>; dri-devel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] dma-buf/reservation: should keep later one in add fence(v2)
On 2018年03月06日 11:53, Monk Liu wrote:
> v2:
> still check context first to avoid warning from dma_fence_is_later
> apply this fix in add_shared_replace as well
>
> Change-Id: If6a979ba9fd6c923b82212f35f07a9ff31c86767
> Signed-off-by: Monk Liu <Monk.Liu@xxxxxxx>
> ---
> drivers/dma-buf/reservation.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/reservation.c
> b/drivers/dma-buf/reservation.c index 314eb10..c6e3c86 100644
> --- a/drivers/dma-buf/reservation.c
> +++ b/drivers/dma-buf/reservation.c
> @@ -118,7 +118,8 @@ reservation_object_add_shared_inplace(struct reservation_object *obj,
> old_fence = rcu_dereference_protected(fobj->shared[i],
> reservation_object_held(obj));
>
> - if (old_fence->context == fence->context) {
> + if (old_fence->context == fence->context &&
> + dma_fence_is_later(fence, old_fence)) {
> /* memory barrier is added by write_seqcount_begin */
> RCU_INIT_POINTER(fobj->shared[i], fence);
> write_seqcount_end(&obj->seq);
> @@ -179,7 +180,8 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
> check = rcu_dereference_protected(old->shared[i],
> reservation_object_held(obj));
>
> - if (check->context == fence->context ||
> + if ((check->context == fence->context &&
> + dma_fence_is_later(fence, check)) ||
We still need do more for !dma_fence_is_later(fence, check) case, in which, we will don't need add new fence to resv slot.
if ((check->context == fence->context) && dma_fence_is_later(fence, check))
fobj->shared_count = j;
RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
fobj->shared_count++;
} else {
dma_fence_put(fence);
}
Regards,
David Zhou
> dma_fence_is_signaled(check))
> RCU_INIT_POINTER(fobj->shared[--k], check);
> else
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