/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#include "i915_drv.h"
#include "i915_active.h"
#define BKL(ref) (&(ref)->i915->drm.struct_mutex)
struct active_node {
struct i915_gem_active base;
struct i915_active *ref;
struct rb_node node;
u64 timeline;
};
static void
__active_retire(struct i915_active *ref)
{
GEM_BUG_ON(!ref->count);
if (!--ref->count)
ref->retire(ref);
}
static void
node_retire(struct i915_gem_active *base, struct i915_request *rq)
{
__active_retire(container_of(base, struct active_node, base)->ref);
}
static void
last_retire(struct i915_gem_active *base, struct i915_request *rq)
{
__active_retire(container_of(base, struct i915_active, last));
}
static struct i915_gem_active *
active_instance(struct i915_active *ref, u64 idx)
{
struct active_node *node;
struct rb_node **p, *parent;
struct i915_request *old;
/*
* We track the most recently used timeline to skip a rbtree search
* for the common case, under typical loads we never need the rbtree
* at all. We can reuse the last slot if it is empty, that is
* after the previous activity has been retired, or if it matches the
* current timeline.
*
* Note that we allow the timeline to be active simultaneously in
* the rbtree and the last cache. We do this to avoid having
* to search and replace the rbtree element for a new timeline, with
* the cost being that we must be aware that the ref may be retired
* twice for the same timeline (as the older rbtree element will be
* retired before the new request added to last).
*/
old = i915_gem_active_raw(&ref->last, BKL(ref));
if (!old || old->fence.context == idx)
goto out;
/* Move the currently active fence into the rbtree */
idx = old->fence.context;
parent = NULL;
p = &ref->tree.rb_node;
while (*p) {
parent = *p;
node = rb_entry(parent, struct active_node, node);
if (node->timeline == idx)
goto replace;
if (node->timeline < idx)
p = &parent->rb_right;
else
p = &parent->rb_left;
}
node = kmalloc(sizeof(*node), GFP_KERNEL);
/* kmalloc may retire the ref->last (thanks shrinker)! */
if (unlikely(!i915_gem_active_raw(&ref->last, BKL(ref)))) {
kfree(node);
goto out;
}
if (unlikely(!node))
return ERR_PTR(-ENOMEM);
init_request_active(&node->base, node_retire);
node->ref = ref;
node->timeline = idx;
rb_link_node(&node->node, parent, p);
rb_insert_color(&node->node, &ref->tree);
replace:
/*
* Overwrite the previous active slot in the rbtree with last,
* leaving last zeroed. If the previous slot is still active,
* we must be careful as we now only expect to receive one retire
* callback not two, and so much undo the active counting for the
* overwritten slot.
*/
if (i915_gem_active_isset(&node->base)) {
/* Retire ourselves from the old rq->active_list */
__list_del_entry(&node->base.link);
ref->count--;
GEM_BUG_ON(!ref->count);
}
GEM_BUG_ON(list_empty(&ref->last.link));
list_replace_init(&ref->last.link, &node->base.link);
node->base.request = fetch_and_zero(&ref->last.request);
out:
return &ref->last;
}
void i915_active_init(struct drm_i915_private *i915,
struct i915_active *ref,
void (*retire)(struct i915_active *ref))
{
ref->i915 = i915;
ref->retire = retire;
ref->tree = RB_ROOT;
init_request_active(&ref->last, last_retire);
ref->count = 0;
}
int i915_active_ref(struct i915_active *ref,
u64 timeline,
struct i915_request *rq)
{
struct i915_gem_active *active;
active = active_instance(ref, timeline);
if (IS_ERR(active))
return PTR_ERR(active);
if (!i915_gem_active_isset(active))
ref->count++;
i915_gem_active_set(active, rq);
GEM_BUG_ON(!ref->count);
return 0;
}
bool i915_active_acquire(struct i915_active *ref)
{
lockdep_assert_held(BKL(ref));
return !ref->count++;
}
void i915_active_release(struct i915_active *ref)
{
lockdep_assert_held(BKL(ref));
__active_retire(ref);
}
int i915_active_wait(struct i915_active *ref)
{
struct active_node *it, *n;
int ret = 0;
if (i915_active_acquire(ref))
goto out_release;
ret = i915_gem_active_retire(&ref->last, BKL(ref));
if (ret)
goto out_release;
rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
ret = i915_gem_active_retire(&it->base, BKL(ref));
if (ret)
break;
}
out_release:
i915_active_release(ref);
return ret;
}
static int __i915_request_await_active(struct i915_request *rq,
struct i915_gem_active *active)
{
struct i915_request *barrier =
i915_gem_active_raw(active, &rq->i915->drm.struct_mutex);
return barrier ? i915_request_await_dma_fence(rq, &barrier->fence) : 0;
}
int i915_request_await_active(struct i915_request *rq, struct i915_active *ref)
{
struct active_node *it, *n;
int ret;
ret = __i915_request_await_active(rq, &ref->last);
if (ret)
return ret;
rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
ret = __i915_request_await_active(rq, &it->base);
if (ret)
return ret;
}
return 0;
}
void i915_active_fini(struct i915_active *ref)
{
struct active_node *it, *n;
GEM_BUG_ON(i915_gem_active_isset(&ref->last));
rbtree_postorder_for_each_entry_safe(it, n, &ref->tree, node) {
GEM_BUG_ON(i915_gem_active_isset(&it->base));
kfree(it);
}
ref->tree = RB_ROOT;
}
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftests/i915_active.c"
#endif
