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drm/i915: Split i915_active.mutex into an irq-safe spinlock for the rbtree

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As we want to be able to run inside atomic context for retiring the
i915_active, and we are no longer allowed to abuse mutex_trylock, split
the tree management portion of i915_active.mutex into an irq-safe
spinlock.

References: a0855d24fc ("locking/mutex: Complain upon mutex API misuse in IRQ contexts")
References: https://bugs.freedesktop.org/show_bug.cgi?id=111626
Fixes: 274cbf20fd ("drm/i915: Push the i915_active.retire into a worker")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191114172535.1116-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-11-14 17:25:35 +00:00
parent 3fb33cd32f
commit c9ad602fea
3 changed files with 31 additions and 31 deletions
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57
drivers/gpu/drm/i915/i915_active.c
View File

@ -91,14 +91,15 @@ static void debug_active_init(struct i915_active *ref)
static void debug_active_activate(struct i915_active *ref)
{
lockdep_assert_held(&ref->mutex);
spin_lock_irq(&ref->tree_lock);
if (!atomic_read(&ref->count)) /* before the first inc */
debug_object_activate(ref, &active_debug_desc);
spin_unlock_irq(&ref->tree_lock);
}
static void debug_active_deactivate(struct i915_active *ref)
{
lockdep_assert_held(&ref->mutex);
lockdep_assert_held(&ref->tree_lock);
if (!atomic_read(&ref->count)) /* after the last dec */
debug_object_deactivate(ref, &active_debug_desc);
}
@ -128,29 +129,22 @@ __active_retire(struct i915_active *ref)
{
struct active_node *it, *n;
struct rb_root root;
bool retire = false;
unsigned long flags;
lockdep_assert_held(&ref->mutex);
GEM_BUG_ON(i915_active_is_idle(ref));
/* return the unused nodes to our slabcache -- flushing the allocator */
if (atomic_dec_and_test(&ref->count)) {
debug_active_deactivate(ref);
root = ref->tree;
ref->tree = RB_ROOT;
ref->cache = NULL;
retire = true;
}
mutex_unlock(&ref->mutex);
if (!retire)
if (!atomic_dec_and_lock_irqsave(&ref->count, &ref->tree_lock, flags))
return;
GEM_BUG_ON(rcu_access_pointer(ref->excl.fence));
rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
GEM_BUG_ON(i915_active_fence_isset(&it->base));
kmem_cache_free(global.slab_cache, it);
}
debug_active_deactivate(ref);
root = ref->tree;
ref->tree = RB_ROOT;
ref->cache = NULL;
spin_unlock_irqrestore(&ref->tree_lock, flags);
/* After the final retire, the entire struct may be freed */
if (ref->retire)
@ -158,6 +152,11 @@ __active_retire(struct i915_active *ref)
/* ... except if you wait on it, you must manage your own references! */
wake_up_var(ref);
rbtree_postorder_for_each_entry_safe(it, n, &root, node) {
GEM_BUG_ON(i915_active_fence_isset(&it->base));
kmem_cache_free(global.slab_cache, it);
}
}
static void
@ -169,7 +168,6 @@ active_work(struct work_struct *wrk)
if (atomic_add_unless(&ref->count, -1, 1))
return;
mutex_lock(&ref->mutex);
__active_retire(ref);
}
@ -180,9 +178,7 @@ active_retire(struct i915_active *ref)
if (atomic_add_unless(&ref->count, -1, 1))
return;
/* If we are inside interrupt context (fence signaling), defer */
if (ref->flags & I915_ACTIVE_RETIRE_SLEEPS ||
!mutex_trylock(&ref->mutex)) {
if (ref->flags & I915_ACTIVE_RETIRE_SLEEPS) {
queue_work(system_unbound_wq, &ref->work);
return;
}
@ -227,7 +223,7 @@ active_instance(struct i915_active *ref, struct intel_timeline *tl)
if (!prealloc)
return NULL;
mutex_lock(&ref->mutex);
spin_lock_irq(&ref->tree_lock);
GEM_BUG_ON(i915_active_is_idle(ref));
parent = NULL;
@ -257,7 +253,7 @@ active_instance(struct i915_active *ref, struct intel_timeline *tl)
out:
ref->cache = node;
mutex_unlock(&ref->mutex);
spin_unlock_irq(&ref->tree_lock);
BUILD_BUG_ON(offsetof(typeof(*node), base));
return &node->base;
@ -278,8 +274,10 @@ void __i915_active_init(struct i915_active *ref,
if (bits & I915_ACTIVE_MAY_SLEEP)
ref->flags |= I915_ACTIVE_RETIRE_SLEEPS;
spin_lock_init(&ref->tree_lock);
ref->tree = RB_ROOT;
ref->cache = NULL;
init_llist_head(&ref->preallocated_barriers);
atomic_set(&ref->count, 0);
__mutex_init(&ref->mutex, "i915_active", key);
@ -510,7 +508,7 @@ static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
if (RB_EMPTY_ROOT(&ref->tree))
return NULL;
mutex_lock(&ref->mutex);
spin_lock_irq(&ref->tree_lock);
GEM_BUG_ON(i915_active_is_idle(ref));
/*
@ -575,7 +573,7 @@ static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
goto match;
}
mutex_unlock(&ref->mutex);
spin_unlock_irq(&ref->tree_lock);
return NULL;
@ -583,7 +581,7 @@ static struct active_node *reuse_idle_barrier(struct i915_active *ref, u64 idx)
rb_erase(p, &ref->tree); /* Hide from waits and sibling allocations */
if (p == &ref->cache->node)
ref->cache = NULL;
mutex_unlock(&ref->mutex);
spin_unlock_irq(&ref->tree_lock);
return rb_entry(p, struct active_node, node);
}
@ -664,6 +662,7 @@ int i915_active_acquire_preallocate_barrier(struct i915_active *ref,
void i915_active_acquire_barrier(struct i915_active *ref)
{
struct llist_node *pos, *next;
unsigned long flags;
GEM_BUG_ON(i915_active_is_idle(ref));
@ -673,7 +672,7 @@ void i915_active_acquire_barrier(struct i915_active *ref)
* populated by i915_request_add_active_barriers() to point to the
* request that will eventually release them.
*/
mutex_lock_nested(&ref->mutex, SINGLE_DEPTH_NESTING);
spin_lock_irqsave_nested(&ref->tree_lock, flags, SINGLE_DEPTH_NESTING);
llist_for_each_safe(pos, next, take_preallocated_barriers(ref)) {
struct active_node *node = barrier_from_ll(pos);
struct intel_engine_cs *engine = barrier_to_engine(node);
@ -699,7 +698,7 @@ void i915_active_acquire_barrier(struct i915_active *ref)
llist_add(barrier_to_ll(node), &engine->barrier_tasks);
intel_engine_pm_put(engine);
}
mutex_unlock(&ref->mutex);
spin_unlock_irqrestore(&ref->tree_lock, flags);
}
void i915_request_add_active_barriers(struct i915_request *rq)

1
drivers/gpu/drm/i915/i915_active_types.h
View File

@ -48,6 +48,7 @@ struct i915_active {
atomic_t count;
struct mutex mutex;
spinlock_t tree_lock;
struct active_node *cache;
struct rb_root tree;

4
drivers/gpu/drm/i915/selftests/i915_active.c
View File

@ -277,8 +277,8 @@ void i915_active_unlock_wait(struct i915_active *ref)
}
/* And wait for the retire callback */
mutex_lock(&ref->mutex);
mutex_unlock(&ref->mutex);
spin_lock_irq(&ref->tree_lock);
spin_unlock_irq(&ref->tree_lock);
/* ... which may have been on a thread instead */
flush_work(&ref->work);