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[RFC,04/12] drm/i915: Use explicit flag to mark unreachable intel_context

Message ID 20200309183129.2296-5-tvrtko.ursulin@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series Per client engine busyness | expand

Commit Message

Tvrtko Ursulin March 9, 2020, 6:31 p.m. UTC 
From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

I need to keep the GEM context around a bit longer so adding an explicit
flag for syncing execbuf with closed/abandonded contexts.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c    | 3 ++-
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 4 ++--
 drivers/gpu/drm/i915/gt/intel_context_types.h  | 1 +
 3 files changed, 5 insertions(+), 3 deletions(-)

Comments

Chris Wilson March 10, 2020, 3:30 p.m. UTC | #1 
Quoting Tvrtko Ursulin (2020-03-09 18:31:21)
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 0893ce781a84..0302757396d5 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -2547,8 +2547,8 @@ static void eb_request_add(struct i915_execbuffer *eb)
>         prev = __i915_request_commit(rq);
>  
>         /* Check that the context wasn't destroyed before submission */
> -       if (likely(rcu_access_pointer(eb->context->gem_context))) {
> -               attr = eb->gem_context->sched;
> +       if (likely(!READ_ONCE(eb->context->closed))) {
> +               attr = rcu_dereference(eb->gem_context)->sched;

That's the warn. We don't have a rcu_read_lock here so it complains.

eb->gem_context is a strong ref, no rcu markup require.
(it's the eb->context->gem_context that needs annotation)
-Chris
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 0f4150c8d7fe..abc3a3e2fcf1 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -568,7 +568,8 @@  static void engines_idle_release(struct i915_gem_context *ctx,
 		int err = 0;
 
 		/* serialises with execbuf */
-		RCU_INIT_POINTER(ce->gem_context, NULL);
+		smp_store_mb(ce->closed, true);
+
 		if (!intel_context_pin_if_active(ce))
 			continue;
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 0893ce781a84..0302757396d5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2547,8 +2547,8 @@  static void eb_request_add(struct i915_execbuffer *eb)
 	prev = __i915_request_commit(rq);
 
 	/* Check that the context wasn't destroyed before submission */
-	if (likely(rcu_access_pointer(eb->context->gem_context))) {
-		attr = eb->gem_context->sched;
+	if (likely(!READ_ONCE(eb->context->closed))) {
+		attr = rcu_dereference(eb->gem_context)->sched;
 
 		/*
 		 * Boost actual workloads past semaphores!
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 11278343b9b5..c60490e756f9 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -50,6 +50,7 @@  struct intel_context {
 
 	struct i915_address_space *vm;
 	struct i915_gem_context __rcu *gem_context;
+	bool closed;
 
 	struct list_head signal_link;
 	struct list_head signals;