In preparation for making eb_vma bigger and heavy to run inn parallel,
we need to stop apply an in-place swap() to reorder around ww_mutex
deadlocks. Keep the array intact and reorder the locks using a dedicated
list.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
.../gpu/drm/i915/gem/i915_gem_execbuffer.c | 48 +++++++++++--------
drivers/gpu/drm/i915/i915_utils.h | 6 +++
2 files changed, 34 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 67ba33b3de60..0d773767c2ac 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -36,6 +36,7 @@ struct eb_vma {
struct drm_i915_gem_exec_object2 *exec;
struct list_head bind_link;
struct list_head reloc_link;
+ struct list_head lock_link;
struct hlist_node node;
u32 handle;
@@ -254,6 +255,8 @@ struct i915_execbuffer {
/** list of vma that have execobj.relocation_count */
struct list_head relocs;
+ struct list_head lock;
+
/**
* Track the most recently used object for relocations, as we
* frequently have to perform multiple relocations within the same
@@ -399,6 +402,10 @@ static int eb_create(struct i915_execbuffer *eb)
eb->lut_size = -eb->buffer_count;
}
+ INIT_LIST_HEAD(&eb->relocs);
+ INIT_LIST_HEAD(&eb->unbound);
+ INIT_LIST_HEAD(&eb->lock);
+
return 0;
}
@@ -604,6 +611,8 @@ eb_add_vma(struct i915_execbuffer *eb,
eb_unreserve_vma(ev);
list_add_tail(&ev->bind_link, &eb->unbound);
}
+
+ list_add_tail(&ev->lock_link, &eb->lock);
}
static inline int use_cpu_reloc(const struct reloc_cache *cache,
@@ -880,9 +889,6 @@ static int eb_lookup_vmas(struct i915_execbuffer *eb)
unsigned int i;
int err = 0;
- INIT_LIST_HEAD(&eb->relocs);
- INIT_LIST_HEAD(&eb->unbound);
-
for (i = 0; i < eb->buffer_count; i++) {
struct i915_vma *vma;
@@ -1790,38 +1796,39 @@ static int eb_relocate(struct i915_execbuffer *eb)
static int eb_move_to_gpu(struct i915_execbuffer *eb)
{
- const unsigned int count = eb->buffer_count;
struct ww_acquire_ctx acquire;
- unsigned int i;
+ struct eb_vma *ev;
int err = 0;
ww_acquire_init(&acquire, &reservation_ww_class);
- for (i = 0; i < count; i++) {
- struct eb_vma *ev = &eb->vma[i];
+ list_for_each_entry(ev, &eb->lock, lock_link) {
struct i915_vma *vma = ev->vma;
err = ww_mutex_lock_interruptible(&vma->resv->lock, &acquire);
if (err == -EDEADLK) {
- GEM_BUG_ON(i == 0);
- do {
- int j = i - 1;
+ struct eb_vma *unlock = ev, *en;
- ww_mutex_unlock(&eb->vma[j].vma->resv->lock);
-
- swap(eb->vma[i], eb->vma[j]);
- } while (--i);
+ list_for_each_entry_safe_continue_reverse(unlock, en, &eb->lock, lock_link) {
+ ww_mutex_unlock(&unlock->vma->resv->lock);
+ list_move_tail(&unlock->lock_link, &eb->lock);
+ }
+ GEM_BUG_ON(!list_is_first(&ev->lock_link, &eb->lock));
err = ww_mutex_lock_slow_interruptible(&vma->resv->lock,
&acquire);
}
- if (err)
- break;
+ if (err) {
+ list_for_each_entry_continue_reverse(ev, &eb->lock, lock_link)
+ ww_mutex_unlock(&ev->vma->resv->lock);
+
+ ww_acquire_fini(&acquire);
+ goto err_skip;
+ }
}
ww_acquire_done(&acquire);
- while (i--) {
- struct eb_vma *ev = &eb->vma[i];
+ list_for_each_entry(ev, &eb->lock, lock_link) {
struct i915_vma *vma = ev->vma;
unsigned int flags = ev->flags;
struct drm_i915_gem_object *obj = vma->obj;
@@ -2122,9 +2129,10 @@ static int eb_parse(struct i915_execbuffer *eb)
if (err)
goto err_trampoline;
- eb->vma[eb->buffer_count].vma = i915_vma_get(shadow);
- eb->vma[eb->buffer_count].flags = __EXEC_OBJECT_HAS_PIN;
eb->batch = &eb->vma[eb->buffer_count++];
+ eb->batch->vma = i915_vma_get(shadow);
+ eb->batch->flags = __EXEC_OBJECT_HAS_PIN;
+ list_add_tail(&eb->batch->lock_link, &eb->lock);
eb->vma[eb->buffer_count].vma = NULL;
eb->trampoline = trampoline;
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 03a73d2bd50d..28813806bc19 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -266,6 +266,12 @@ static inline int list_is_last_rcu(const struct list_head *list,
return READ_ONCE(list->next) == head;
}
+#define list_for_each_entry_safe_continue_reverse(pos, n, head, member) \
+ for (pos = list_prev_entry(pos, member), \
+ n = list_prev_entry(pos, member); \
+ &pos->member != (head); \
+ pos = n, n = list_prev_entry(n, member))
+
/*
* Wait until the work is finally complete, even if it tries to postpone
* by requeueing itself. Note, that if the worker never cancels itself,
--
2.20.1
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