[PATCH 19/22] drm/i915: Allow contexts to be unreferenced locklessly
Chris Wilson
chris at chris-wilson.co.uk
Fri May 19 09:53:19 UTC 2017
If we move the actual cleanup of the context to a worker, we can allow
the final free to be called from any context and avoid undue latency in
the caller.
v2: Negotiate handling the delayed contexts free by flushing the
workqueue before calling i915_gem_context_fini() and performing the final
free of the kernel context directly
v3: Flush deferred frees before new context allocations
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
drivers/gpu/drm/i915/gvt/scheduler.c | 2 +-
drivers/gpu/drm/i915/i915_drv.c | 2 +
drivers/gpu/drm/i915/i915_drv.h | 23 +--------
drivers/gpu/drm/i915/i915_gem_context.c | 59 +++++++++++++++++++-----
drivers/gpu/drm/i915/i915_gem_context.h | 15 +++++-
drivers/gpu/drm/i915/i915_perf.c | 4 +-
drivers/gpu/drm/i915/selftests/i915_vma.c | 8 +++-
drivers/gpu/drm/i915/selftests/mock_context.c | 9 ++++
drivers/gpu/drm/i915/selftests/mock_context.h | 2 +
drivers/gpu/drm/i915/selftests/mock_gem_device.c | 3 +-
10 files changed, 88 insertions(+), 39 deletions(-)
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 6ae286cb5804..84c2495df372 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -595,7 +595,7 @@ int intel_gvt_init_workload_scheduler(struct intel_gvt *gvt)
void intel_vgpu_clean_gvt_context(struct intel_vgpu *vgpu)
{
- i915_gem_context_put_unlocked(vgpu->shadow_ctx);
+ i915_gem_context_put(vgpu->shadow_ctx);
}
int intel_vgpu_init_gvt_context(struct intel_vgpu *vgpu)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6c91bc9f7e2b..2d2fb4327f97 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -550,6 +550,8 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
static void i915_gem_fini(struct drm_i915_private *dev_priv)
{
+ flush_workqueue(dev_priv->wq);
+
mutex_lock(&dev_priv->drm.struct_mutex);
intel_uc_fini_hw(dev_priv);
i915_gem_cleanup_engines(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 61a0c81164cc..f11c06bd977e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2313,6 +2313,8 @@ struct drm_i915_private {
struct {
struct list_head list;
+ struct llist_head free_list;
+ struct work_struct free_work;
/* The hw wants to have a stable context identifier for the
* lifetime of the context (for OA, PASID, faults, etc).
@@ -3497,27 +3499,6 @@ i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id)
return ctx;
}
-static inline struct i915_gem_context *
-i915_gem_context_get(struct i915_gem_context *ctx)
-{
- kref_get(&ctx->ref);
- return ctx;
-}
-
-static inline void i915_gem_context_put(struct i915_gem_context *ctx)
-{
- lockdep_assert_held(&ctx->i915->drm.struct_mutex);
- kref_put(&ctx->ref, i915_gem_context_free);
-}
-
-static inline void i915_gem_context_put_unlocked(struct i915_gem_context *ctx)
-{
- struct mutex *lock = &ctx->i915->drm.struct_mutex;
-
- if (kref_put_mutex(&ctx->ref, i915_gem_context_free, lock))
- mutex_unlock(lock);
-}
-
static inline struct intel_timeline *
i915_gem_context_lookup_timeline(struct i915_gem_context *ctx,
struct intel_engine_cs *engine)
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index f4395a1e214d..2ad78bb50137 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -158,13 +158,11 @@ static void vma_lut_free(struct i915_gem_context *ctx)
kvfree(lut->ht);
}
-void i915_gem_context_free(struct kref *ctx_ref)
+static void i915_gem_context_free(struct i915_gem_context *ctx)
{
- struct i915_gem_context *ctx = container_of(ctx_ref, typeof(*ctx), ref);
int i;
lockdep_assert_held(&ctx->i915->drm.struct_mutex);
- trace_i915_context_free(ctx);
GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
vma_lut_free(ctx);
@@ -192,6 +190,37 @@ void i915_gem_context_free(struct kref *ctx_ref)
kfree(ctx);
}
+static void contexts_free(struct drm_i915_private *i915)
+{
+ struct llist_node *freed = llist_del_all(&i915->contexts.free_list);
+ struct i915_gem_context *ctx;
+
+ lockdep_assert_held(&i915->drm.struct_mutex);
+
+ llist_for_each_entry(ctx, freed, free_link)
+ i915_gem_context_free(ctx);
+}
+
+static void contexts_free_worker(struct work_struct *work)
+{
+ struct drm_i915_private *i915 =
+ container_of(work, typeof(*i915), contexts.free_work);
+
+ mutex_lock(&i915->drm.struct_mutex);
+ contexts_free(i915);
+ mutex_unlock(&i915->drm.struct_mutex);
+}
+
+void i915_gem_context_release(struct kref *ref)
+{
+ struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref);
+ struct drm_i915_private *i915 = ctx->i915;
+
+ trace_i915_context_free(ctx);
+ if (llist_add(&ctx->free_link, &i915->contexts.free_list))
+ queue_work(i915->wq, &i915->contexts.free_work);
+}
+
static void context_close(struct i915_gem_context *ctx)
{
i915_gem_context_set_closed(ctx);
@@ -428,6 +457,8 @@ int i915_gem_contexts_init(struct drm_i915_private *dev_priv)
return 0;
INIT_LIST_HEAD(&dev_priv->contexts.list);
+ INIT_WORK(&dev_priv->contexts.free_work, contexts_free_worker);
+ init_llist_head(&dev_priv->contexts.free_list);
if (intel_vgpu_active(dev_priv) &&
HAS_LOGICAL_RING_CONTEXTS(dev_priv)) {
@@ -505,18 +536,20 @@ void i915_gem_contexts_lost(struct drm_i915_private *dev_priv)
}
}
-void i915_gem_contexts_fini(struct drm_i915_private *dev_priv)
+void i915_gem_contexts_fini(struct drm_i915_private *i915)
{
- struct i915_gem_context *dctx = dev_priv->kernel_context;
-
- lockdep_assert_held(&dev_priv->drm.struct_mutex);
+ struct i915_gem_context *ctx;
- GEM_BUG_ON(!i915_gem_context_is_kernel(dctx));
+ lockdep_assert_held(&i915->drm.struct_mutex);
- context_close(dctx);
- dev_priv->kernel_context = NULL;
+ /* Keep the context so that we can free it immediately ourselves */
+ ctx = i915_gem_context_get(fetch_and_zero(&i915->kernel_context));
+ GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));
+ context_close(ctx);
+ i915_gem_context_free(ctx);
- ida_destroy(&dev_priv->contexts.hw_ida);
+ /* Must free all deferred contexts (via flush_workqueue) first */
+ ida_destroy(&i915->contexts.hw_ida);
}
static int context_idr_cleanup(int id, void *p, void *data)
@@ -957,6 +990,10 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
if (ret)
return ret;
+ /* Reap stale contexts */
+ i915_gem_retire_requests(dev_priv);
+ contexts_free(dev_priv);
+
ctx = i915_gem_create_context(dev_priv, file_priv);
mutex_unlock(&dev->struct_mutex);
if (IS_ERR(ctx))
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index 808f878db812..61146f4aa168 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -86,6 +86,7 @@ struct i915_gem_context {
/** link: place with &drm_i915_private.context_list */
struct list_head link;
+ struct llist_node free_link;
/**
* @ref: reference count
@@ -284,7 +285,7 @@ void i915_gem_context_close(struct drm_file *file);
int i915_switch_context(struct drm_i915_gem_request *req);
int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv);
-void i915_gem_context_free(struct kref *ctx_ref);
+void i915_gem_context_release(struct kref *ctx_ref);
struct i915_gem_context *
i915_gem_context_create_gvt(struct drm_device *dev);
@@ -299,4 +300,16 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void *data,
struct drm_file *file);
+static inline struct i915_gem_context *
+i915_gem_context_get(struct i915_gem_context *ctx)
+{
+ kref_get(&ctx->ref);
+ return ctx;
+}
+
+static inline void i915_gem_context_put(struct i915_gem_context *ctx)
+{
+ kref_put(&ctx->ref, i915_gem_context_release);
+}
+
#endif /* !__I915_GEM_CONTEXT_H__ */
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 85269bcc8372..8b5010c5c736 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -1680,7 +1680,7 @@ static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
list_del(&stream->link);
if (stream->ctx)
- i915_gem_context_put_unlocked(stream->ctx);
+ i915_gem_context_put(stream->ctx);
kfree(stream);
}
@@ -1851,7 +1851,7 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
kfree(stream);
err_ctx:
if (specific_ctx)
- i915_gem_context_put_unlocked(specific_ctx);
+ i915_gem_context_put(specific_ctx);
err:
return ret;
}
diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
index fb9072d5877f..2e86ec136b35 100644
--- a/drivers/gpu/drm/i915/selftests/i915_vma.c
+++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
@@ -186,16 +186,20 @@ static int igt_vma_create(void *arg)
goto end;
}
- list_for_each_entry_safe(ctx, cn, &contexts, link)
+ list_for_each_entry_safe(ctx, cn, &contexts, link) {
+ list_del_init(&ctx->link);
mock_context_close(ctx);
+ }
}
end:
/* Final pass to lookup all created contexts */
err = create_vmas(i915, &objects, &contexts);
out:
- list_for_each_entry_safe(ctx, cn, &contexts, link)
+ list_for_each_entry_safe(ctx, cn, &contexts, link) {
+ list_del_init(&ctx->link);
mock_context_close(ctx);
+ }
list_for_each_entry_safe(obj, on, &objects, st_link)
i915_gem_object_put(obj);
diff --git a/drivers/gpu/drm/i915/selftests/mock_context.c b/drivers/gpu/drm/i915/selftests/mock_context.c
index 243325b97d4c..9c7c68181f82 100644
--- a/drivers/gpu/drm/i915/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/selftests/mock_context.c
@@ -86,3 +86,12 @@ void mock_context_close(struct i915_gem_context *ctx)
i915_gem_context_put(ctx);
}
+
+void mock_init_contexts(struct drm_i915_private *i915)
+{
+ INIT_LIST_HEAD(&i915->contexts.list);
+ ida_init(&i915->contexts.hw_ida);
+
+ INIT_WORK(&i915->contexts.free_work, contexts_free_worker);
+ init_llist_head(&i915->contexts.free_list);
+}
diff --git a/drivers/gpu/drm/i915/selftests/mock_context.h b/drivers/gpu/drm/i915/selftests/mock_context.h
index 2427e5c0916a..383941a61124 100644
--- a/drivers/gpu/drm/i915/selftests/mock_context.h
+++ b/drivers/gpu/drm/i915/selftests/mock_context.h
@@ -25,6 +25,8 @@
#ifndef __MOCK_CONTEXT_H
#define __MOCK_CONTEXT_H
+void mock_init_contexts(struct drm_i915_private *i915);
+
struct i915_gem_context *
mock_context(struct drm_i915_private *i915,
const char *name);
diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
index 0ddb70a16550..47613d20bba8 100644
--- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c
+++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
@@ -57,6 +57,7 @@ static void mock_device_release(struct drm_device *dev)
cancel_delayed_work_sync(&i915->gt.retire_work);
cancel_delayed_work_sync(&i915->gt.idle_work);
+ flush_workqueue(i915->wq);
mutex_lock(&i915->drm.struct_mutex);
for_each_engine(engine, i915, id)
@@ -160,7 +161,7 @@ struct drm_i915_private *mock_gem_device(void)
INIT_LIST_HEAD(&i915->mm.unbound_list);
INIT_LIST_HEAD(&i915->mm.bound_list);
- ida_init(&i915->contexts.hw_ida);
+ mock_init_contexts(i915);
INIT_DELAYED_WORK(&i915->gt.retire_work, mock_retire_work_handler);
INIT_DELAYED_WORK(&i915->gt.idle_work, mock_idle_work_handler);
--
2.11.0
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