[PATCH 1/8] dma-buf: remove shared fence staging in reservation object
Christian König
ckoenig.leichtzumerken at gmail.com
Thu Oct 4 13:12:43 UTC 2018
No need for that any more. Just replace the list when there isn't enough
room any more for the additional fence.
Signed-off-by: Christian König <christian.koenig at amd.com>
---
drivers/dma-buf/reservation.c | 178 ++++++++++++++----------------------------
include/linux/reservation.h | 4 -
2 files changed, 58 insertions(+), 124 deletions(-)
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 6c95f61a32e7..5825fc336a13 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -68,105 +68,23 @@ EXPORT_SYMBOL(reservation_seqcount_string);
*/
int reservation_object_reserve_shared(struct reservation_object *obj)
{
- struct reservation_object_list *fobj, *old;
- u32 max;
+ struct reservation_object_list *old, *new;
+ unsigned int i, j, k, max;
old = reservation_object_get_list(obj);
if (old && old->shared_max) {
- if (old->shared_count < old->shared_max) {
- /* perform an in-place update */
- kfree(obj->staged);
- obj->staged = NULL;
+ if (old->shared_count < old->shared_max)
return 0;
- } else
+ else
max = old->shared_max * 2;
- } else
- max = 4;
-
- /*
- * resize obj->staged or allocate if it doesn't exist,
- * noop if already correct size
- */
- fobj = krealloc(obj->staged, offsetof(typeof(*fobj), shared[max]),
- GFP_KERNEL);
- if (!fobj)
- return -ENOMEM;
-
- obj->staged = fobj;
- fobj->shared_max = max;
- return 0;
-}
-EXPORT_SYMBOL(reservation_object_reserve_shared);
-
-static void
-reservation_object_add_shared_inplace(struct reservation_object *obj,
- struct reservation_object_list *fobj,
- struct dma_fence *fence)
-{
- struct dma_fence *signaled = NULL;
- u32 i, signaled_idx;
-
- dma_fence_get(fence);
-
- preempt_disable();
- write_seqcount_begin(&obj->seq);
-
- for (i = 0; i < fobj->shared_count; ++i) {
- struct dma_fence *old_fence;
-
- old_fence = rcu_dereference_protected(fobj->shared[i],
- reservation_object_held(obj));
-
- if (old_fence->context == fence->context) {
- /* memory barrier is added by write_seqcount_begin */
- RCU_INIT_POINTER(fobj->shared[i], fence);
- write_seqcount_end(&obj->seq);
- preempt_enable();
-
- dma_fence_put(old_fence);
- return;
- }
-
- if (!signaled && dma_fence_is_signaled(old_fence)) {
- signaled = old_fence;
- signaled_idx = i;
- }
- }
-
- /*
- * memory barrier is added by write_seqcount_begin,
- * fobj->shared_count is protected by this lock too
- */
- if (signaled) {
- RCU_INIT_POINTER(fobj->shared[signaled_idx], fence);
} else {
- BUG_ON(fobj->shared_count >= fobj->shared_max);
- RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
- fobj->shared_count++;
+ max = 4;
}
- write_seqcount_end(&obj->seq);
- preempt_enable();
-
- dma_fence_put(signaled);
-}
-
-static void
-reservation_object_add_shared_replace(struct reservation_object *obj,
- struct reservation_object_list *old,
- struct reservation_object_list *fobj,
- struct dma_fence *fence)
-{
- unsigned i, j, k;
-
- dma_fence_get(fence);
-
- if (!old) {
- RCU_INIT_POINTER(fobj->shared[0], fence);
- fobj->shared_count = 1;
- goto done;
- }
+ new = kmalloc(offsetof(typeof(*new), shared[max]), GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
/*
* no need to bump fence refcounts, rcu_read access
@@ -174,46 +92,45 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
* references from the old struct are carried over to
* the new.
*/
- for (i = 0, j = 0, k = fobj->shared_max; i < old->shared_count; ++i) {
- struct dma_fence *check;
+ for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) {
+ struct dma_fence *fence;
- check = rcu_dereference_protected(old->shared[i],
- reservation_object_held(obj));
-
- if (check->context == fence->context ||
- dma_fence_is_signaled(check))
- RCU_INIT_POINTER(fobj->shared[--k], check);
+ fence = rcu_dereference_protected(old->shared[i],
+ reservation_object_held(obj));
+ if (dma_fence_is_signaled(fence))
+ RCU_INIT_POINTER(new->shared[--k], fence);
else
- RCU_INIT_POINTER(fobj->shared[j++], check);
+ RCU_INIT_POINTER(new->shared[j++], fence);
}
- fobj->shared_count = j;
- RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);
- fobj->shared_count++;
+ new->shared_count = j;
+ new->shared_max = max;
-done:
preempt_disable();
write_seqcount_begin(&obj->seq);
/*
* RCU_INIT_POINTER can be used here,
* seqcount provides the necessary barriers
*/
- RCU_INIT_POINTER(obj->fence, fobj);
+ RCU_INIT_POINTER(obj->fence, new);
write_seqcount_end(&obj->seq);
preempt_enable();
if (!old)
- return;
+ return 0;
/* Drop the references to the signaled fences */
- for (i = k; i < fobj->shared_max; ++i) {
- struct dma_fence *f;
+ for (i = k; i < new->shared_max; ++i) {
+ struct dma_fence *fence;
- f = rcu_dereference_protected(fobj->shared[i],
- reservation_object_held(obj));
- dma_fence_put(f);
+ fence = rcu_dereference_protected(new->shared[i],
+ reservation_object_held(obj));
+ dma_fence_put(fence);
}
kfree_rcu(old, rcu);
+
+ return 0;
}
+EXPORT_SYMBOL(reservation_object_reserve_shared);
/**
* reservation_object_add_shared_fence - Add a fence to a shared slot
@@ -226,15 +143,39 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
void reservation_object_add_shared_fence(struct reservation_object *obj,
struct dma_fence *fence)
{
- struct reservation_object_list *old, *fobj = obj->staged;
+ struct reservation_object_list *fobj;
+ unsigned int i;
- old = reservation_object_get_list(obj);
- obj->staged = NULL;
+ dma_fence_get(fence);
+
+ fobj = reservation_object_get_list(obj);
- if (!fobj)
- reservation_object_add_shared_inplace(obj, old, fence);
- else
- reservation_object_add_shared_replace(obj, old, fobj, fence);
+ preempt_disable();
+ write_seqcount_begin(&obj->seq);
+
+ for (i = 0; i < fobj->shared_count; ++i) {
+ struct dma_fence *old_fence;
+
+ old_fence = rcu_dereference_protected(fobj->shared[i],
+ reservation_object_held(obj));
+ if (old_fence->context == fence->context ||
+ dma_fence_is_signaled(old_fence)) {
+ dma_fence_put(old_fence);
+ goto replace;
+ }
+ }
+
+ BUG_ON(fobj->shared_count >= fobj->shared_max);
+ fobj->shared_count++;
+
+replace:
+ /*
+ * memory barrier is added by write_seqcount_begin,
+ * fobj->shared_count is protected by this lock too
+ */
+ RCU_INIT_POINTER(fobj->shared[i], fence);
+ write_seqcount_end(&obj->seq);
+ preempt_enable();
}
EXPORT_SYMBOL(reservation_object_add_shared_fence);
@@ -343,9 +284,6 @@ int reservation_object_copy_fences(struct reservation_object *dst,
new = dma_fence_get_rcu_safe(&src->fence_excl);
rcu_read_unlock();
- kfree(dst->staged);
- dst->staged = NULL;
-
src_list = reservation_object_get_list(dst);
old = reservation_object_get_excl(dst);
diff --git a/include/linux/reservation.h b/include/linux/reservation.h
index 02166e815afb..54cf6773a14c 100644
--- a/include/linux/reservation.h
+++ b/include/linux/reservation.h
@@ -68,7 +68,6 @@ struct reservation_object_list {
* @seq: sequence count for managing RCU read-side synchronization
* @fence_excl: the exclusive fence, if there is one currently
* @fence: list of current shared fences
- * @staged: staged copy of shared fences for RCU updates
*/
struct reservation_object {
struct ww_mutex lock;
@@ -76,7 +75,6 @@ struct reservation_object {
struct dma_fence __rcu *fence_excl;
struct reservation_object_list __rcu *fence;
- struct reservation_object_list *staged;
};
#define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base)
@@ -95,7 +93,6 @@ reservation_object_init(struct reservation_object *obj)
__seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
RCU_INIT_POINTER(obj->fence, NULL);
RCU_INIT_POINTER(obj->fence_excl, NULL);
- obj->staged = NULL;
}
/**
@@ -124,7 +121,6 @@ reservation_object_fini(struct reservation_object *obj)
kfree(fobj);
}
- kfree(obj->staged);
ww_mutex_destroy(&obj->lock);
}
--
2.14.1
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