drm/i915: Hold a reference to the active HW context

For virtual engines, we need to keep the HW context alive while it
remains in use. For regular HW contexts, they are created and kept alive
until the end of the GEM context. For simplicity, generalise the
requirements and keep an active reference to each HW context.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190318212347.30146-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 21208a865380cb2076592ff56f38bd05e0b8e0b9..d776d43707e0be72488a7fd1ea314afe53fcac91 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -232,7 +232,7 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
        i915_ppgtt_put(ctx->ppgtt);
 
        rbtree_postorder_for_each_entry_safe(it, n, &ctx->hw_contexts, node)
-               it->ops->destroy(it);
+               intel_context_put(it);
 
        kfree(ctx->name);
        put_pid(ctx->pid);

diff --git a/drivers/gpu/drm/i915/intel_context.c b/drivers/gpu/drm/i915/intel_context.c
index 0ab894a058f6eeae445df648b5574c77909a8453..8931e0fee873d48c8adbdba8c951f0b90ec85cc8 100644 (file)
--- a/drivers/gpu/drm/i915/intel_context.c
+++ b/drivers/gpu/drm/i915/intel_context.c
@@ -172,6 +172,7 @@ intel_context_pin(struct i915_gem_context *ctx,
                list_add(&ce->active_link, &ctx->active_engines);
                mutex_unlock(&ctx->mutex);
 
+               intel_context_get(ce);
                smp_mb__before_atomic(); /* flush pin before it is visible */
        }
 
@@ -192,6 +193,7 @@ void intel_context_unpin(struct intel_context *ce)
                return;
 
        /* We may be called from inside intel_context_pin() to evict another */
+       intel_context_get(ce);
        mutex_lock_nested(&ce->pin_mutex, SINGLE_DEPTH_NESTING);
 
        if (likely(atomic_dec_and_test(&ce->pin_count))) {
@@ -202,9 +204,11 @@ void intel_context_unpin(struct intel_context *ce)
                mutex_unlock(&ce->gem_context->mutex);
 
                i915_gem_context_put(ce->gem_context);
+               intel_context_put(ce);
        }
 
        mutex_unlock(&ce->pin_mutex);
+       intel_context_put(ce);
 }
 
 static void intel_context_retire(struct i915_active_request *active,
@@ -221,6 +225,8 @@ intel_context_init(struct intel_context *ce,
                   struct i915_gem_context *ctx,
                   struct intel_engine_cs *engine)
 {
+       kref_init(&ce->ref);
+
        ce->gem_context = ctx;
        ce->engine = engine;
        ce->ops = engine->cops;

diff --git a/drivers/gpu/drm/i915/intel_context.h b/drivers/gpu/drm/i915/intel_context.h
index 9546d932406aa2367fbdd652b6e6ffc200a5c668..ebc861b1a49e2bcf91a4c8b68ce7867b1cc3e42b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_context.h
+++ b/drivers/gpu/drm/i915/intel_context.h
@@ -73,4 +73,15 @@ static inline void __intel_context_pin(struct intel_context *ce)
 
 void intel_context_unpin(struct intel_context *ce);
 
+static inline struct intel_context *intel_context_get(struct intel_context *ce)
+{
+       kref_get(&ce->ref);
+       return ce;
+}
+
+static inline void intel_context_put(struct intel_context *ce)
+{
+       kref_put(&ce->ref, ce->ops->destroy);
+}
+
 #endif /* __INTEL_CONTEXT_H__ */

diff --git a/drivers/gpu/drm/i915/intel_context_types.h b/drivers/gpu/drm/i915/intel_context_types.h
index 6dc9b4b9067be6c93fd04d2eb738bdb4a768091a..624729a3587514d3198b7f86c7b65cf5950dd7de 100644 (file)
--- a/drivers/gpu/drm/i915/intel_context_types.h
+++ b/drivers/gpu/drm/i915/intel_context_types.h
@@ -7,6 +7,7 @@
 #ifndef __INTEL_CONTEXT_TYPES__
 #define __INTEL_CONTEXT_TYPES__
 
+#include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/rbtree.h>
@@ -22,7 +23,8 @@ struct intel_ring;
 struct intel_context_ops {
        int (*pin)(struct intel_context *ce);
        void (*unpin)(struct intel_context *ce);
-       void (*destroy)(struct intel_context *ce);
+
+       void (*destroy)(struct kref *kref);
 };
 
 /*
@@ -36,6 +38,8 @@ struct intel_sseu {
 };
 
 struct intel_context {
+       struct kref ref;
+
        struct i915_gem_context *gem_context;
        struct intel_engine_cs *engine;
        struct intel_engine_cs *active;

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index c949af7be8bddb40cba2bd0b6747e7baf92cb06e..51c2ea164b36f99c834843d472b5358c55085cf9 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1236,8 +1236,10 @@ static void __execlists_context_fini(struct intel_context *ce)
        i915_gem_object_put(ce->state->obj);
 }
 
-static void execlists_context_destroy(struct intel_context *ce)
+static void execlists_context_destroy(struct kref *kref)
 {
+       struct intel_context *ce = container_of(kref, typeof(*ce), ref);
+
        GEM_BUG_ON(intel_context_is_pinned(ce));
 
        if (ce->state)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 81b32bac2bcdf6de595e14656e639f9f7334afc9..9e7ad17b5250d24d725375ea7973128371eec7c2 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1350,8 +1350,10 @@ static void __ring_context_fini(struct intel_context *ce)
        i915_gem_object_put(ce->state->obj);
 }
 
-static void ring_context_destroy(struct intel_context *ce)
+static void ring_context_destroy(struct kref *ref)
 {
+       struct intel_context *ce = container_of(ref, typeof(*ce), ref);
+
        GEM_BUG_ON(intel_context_is_pinned(ce));
 
        if (ce->state)

diff --git a/drivers/gpu/drm/i915/selftests/mock_engine.c b/drivers/gpu/drm/i915/selftests/mock_engine.c
index 7641b74ada98c4cfe858c1c6eb6c5ec6ef702e1a..639d36eb904a802cdcb7b6cbe42b084bf84233e9 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/mock_engine.c
+++ b/drivers/gpu/drm/i915/selftests/mock_engine.c
@@ -128,12 +128,16 @@ static void mock_context_unpin(struct intel_context *ce)
        mock_timeline_unpin(ce->ring->timeline);
 }
 
-static void mock_context_destroy(struct intel_context *ce)
+static void mock_context_destroy(struct kref *ref)
 {
+       struct intel_context *ce = container_of(ref, typeof(*ce), ref);
+
        GEM_BUG_ON(intel_context_is_pinned(ce));
 
        if (ce->ring)
                mock_ring_free(ce->ring);
+
+       intel_context_free(ce);
 }
 
 static int mock_context_pin(struct intel_context *ce)
@@ -151,6 +155,7 @@ static int mock_context_pin(struct intel_context *ce)
 static const struct intel_context_ops mock_context_ops = {
        .pin = mock_context_pin,
        .unpin = mock_context_unpin,
+
        .destroy = mock_context_destroy,
 };