| Message ID | 1520308390-32469-1-git-send-email-Monk.Liu@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@amd.com> > --- > 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
> > - 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@amd.com>; dri-devel@freedesktop.org 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@amd.com> > --- > 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
On 2018年03月06日 13:59, Liu, Monk wrote: >> >> - 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], Yes, if !dma_fence_is_later(fence, check), then 'check' will be put to fobj->shared[++j], so we don't need add new fence to resv slot, don't we? Regards, David Zhou > 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@amd.com>; dri-devel@freedesktop.org > 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@amd.com> >> --- >> 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
Make sense, will give v3 -----Original Message----- From: Zhou, David(ChunMing) Sent: 2018年3月6日 14:08 To: Liu, Monk <Monk.Liu@amd.com>; Zhou, David(ChunMing) <David1.Zhou@amd.com>; dri-devel@freedesktop.org Subject: Re: [PATCH] dma-buf/reservation: should keep later one in add fence(v2) On 2018年03月06日 13:59, Liu, Monk wrote: >> >> - 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], Yes, if !dma_fence_is_later(fence, check), then 'check' will be put to fobj->shared[++j], so we don't need add new fence to resv slot, don't we? Regards, David Zhou > 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@amd.com>; dri-devel@freedesktop.org > 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@amd.com> >> --- >> 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
Quoting Monk Liu (2018-03-06 03:53:10) > 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@amd.com> > --- > 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)) { This should be true by construction. Adding an older fence on the same context is a programming bug, imo. Between different callers the resv should have been locked and the fenced operations serialised, from the same caller, you shouldn't be handling more than one output fence? -Chris
okay
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)) || dma_fence_is_signaled(check)) RCU_INIT_POINTER(fobj->shared[--k], check); else
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@amd.com> --- drivers/dma-buf/reservation.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)