drm/i915: Drop stealing of bits from i915_sw_fence function pointer

Rather than stealing bits from i915_sw_fence function pointer use
separate fields for function pointer and flags. If using two different
fields, the 4 byte alignment for the i915_sw_fence function pointer can
also be dropped.

v2:
 (CI)
  - Set new function field rather than flags in __i915_sw_fence_init
v3:
 (Tvrtko)
  - Remove BUG_ON(!fence->flags) in reinit as that will now blow up
  - Only define fence->flags if CONFIG_DRM_I915_SW_FENCE_CHECK_DAG is
    defined
v4:
  - Rebase, resend for CI

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211116194929.10211-1-matthew.brost@intel.com

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 7ea0dbf81530..2a74a9a1cafe 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -18,7 +18,9 @@
 #define I915_SW_FENCE_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 #endif
 
+#ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
 static DEFINE_SPINLOCK(i915_sw_fence_lock);
+#endif
 
 #define WQ_FLAG_BITS \
 	BITS_PER_TYPE(typeof_member(struct wait_queue_entry, flags))
@@ -34,7 +36,7 @@ enum {
 
 static void *i915_sw_fence_debug_hint(void *addr)
 {
-	return (void *)(((struct i915_sw_fence *)addr)->flags & I915_SW_FENCE_MASK);
+	return (void *)(((struct i915_sw_fence *)addr)->fn);
 }
 
 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
@@ -126,10 +128,7 @@ static inline void debug_fence_assert(struct i915_sw_fence *fence)
 static int __i915_sw_fence_notify(struct i915_sw_fence *fence,
 				  enum i915_sw_fence_notify state)
 {
-	i915_sw_fence_notify_t fn;
-
-	fn = (i915_sw_fence_notify_t)(fence->flags & I915_SW_FENCE_MASK);
-	return fn(fence, state);
+	return fence->fn(fence, state);
 }
 
 #ifdef CONFIG_DRM_I915_SW_FENCE_DEBUG_OBJECTS
@@ -242,10 +241,13 @@ void __i915_sw_fence_init(struct i915_sw_fence *fence,
 			  const char *name,
 			  struct lock_class_key *key)
 {
-	BUG_ON(!fn || (unsigned long)fn & ~I915_SW_FENCE_MASK);
+	BUG_ON(!fn);
 
 	__init_waitqueue_head(&fence->wait, name, key);
-	fence->flags = (unsigned long)fn;
+	fence->fn = fn;
+#ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
+	fence->flags = 0;
+#endif
 
 	i915_sw_fence_reinit(fence);
 }
@@ -257,7 +259,6 @@ void i915_sw_fence_reinit(struct i915_sw_fence *fence)
 	atomic_set(&fence->pending, 1);
 	fence->error = 0;
 
-	I915_SW_FENCE_BUG_ON(!fence->flags);
 	I915_SW_FENCE_BUG_ON(!list_empty(&fence->wait.head));
 }
 
@@ -279,6 +280,7 @@ static int i915_sw_fence_wake(wait_queue_entry_t *wq, unsigned mode, int flags,
 	return 0;
 }
 
+#ifdef CONFIG_DRM_I915_SW_FENCE_CHECK_DAG
 static bool __i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 				    const struct i915_sw_fence * const signaler)
 {
@@ -322,9 +324,6 @@ static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 	unsigned long flags;
 	bool err;
 
-	if (!IS_ENABLED(CONFIG_DRM_I915_SW_FENCE_CHECK_DAG))
-		return false;
-
 	spin_lock_irqsave(&i915_sw_fence_lock, flags);
 	err = __i915_sw_fence_check_if_after(fence, signaler);
 	__i915_sw_fence_clear_checked_bit(fence);
@@ -332,6 +331,13 @@ static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
 
 	return err;
 }
+#else
+static bool i915_sw_fence_check_if_after(struct i915_sw_fence *fence,
+					 const struct i915_sw_fence * const signaler)
+{
+	return false;
+}
+#endif
 
 static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
 					  struct i915_sw_fence *signaler,