drm/i915: Encode fence specific waitqueue behaviour into the wait.flags

Use the wait_queue_entry.flags to denote the special fence behaviour
(flattening continuations along fence chains, and for propagating
errors) rather than trying to detect ordinary waiters by their
functions.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201216165850.25030-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index 038d4c6884c5b708dc102d1b09fa663a17cee701..2744558f3050757f6c90b411f26dbb729999ec4c 100644 (file)
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -18,10 +18,15 @@
 #define I915_SW_FENCE_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 #endif
 
-#define I915_SW_FENCE_FLAG_ALLOC BIT(3) /* after WQ_FLAG_* for safety */
-
 static DEFINE_SPINLOCK(i915_sw_fence_lock);
 
+#define WQ_FLAG_BITS \
+       BITS_PER_TYPE(typeof_member(struct wait_queue_entry, flags))
+
+/* after WQ_FLAG_* for safety */
+#define I915_SW_FENCE_FLAG_FENCE BIT(WQ_FLAG_BITS - 1)
+#define I915_SW_FENCE_FLAG_ALLOC BIT(WQ_FLAG_BITS - 2)
+
 enum {
        DEBUG_FENCE_IDLE = 0,
        DEBUG_FENCE_NOTIFY,
@@ -154,10 +159,10 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
        spin_lock_irqsave_nested(&x->lock, flags, 1 + !!continuation);
        if (continuation) {
                list_for_each_entry_safe(pos, next, &x->head, entry) {
-                       if (pos->func == autoremove_wake_function)
-                               pos->func(pos, TASK_NORMAL, 0, continuation);
-                       else
+                       if (pos->flags & I915_SW_FENCE_FLAG_FENCE)
                                list_move_tail(&pos->entry, continuation);
+                       else
+                               pos->func(pos, TASK_NORMAL, 0, continuation);
                }
        } else {
                LIST_HEAD(extra);
@@ -166,9 +171,9 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,
                        list_for_each_entry_safe(pos, next, &x->head, entry) {
                                int wake_flags;
 
-                               wake_flags = fence->error;
-                               if (pos->func == autoremove_wake_function)
-                                       wake_flags = 0;
+                               wake_flags = 0;
+                               if (pos->flags & I915_SW_FENCE_FLAG_FENCE)
+                                       wake_flags = fence->error;
 
                                pos->func(pos, TASK_NORMAL, wake_flags, &extra);
                        }
@@ -332,8 +337,8 @@ static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
                                          struct i915_sw_fence *signaler,
                                          wait_queue_entry_t *wq, gfp_t gfp)
 {
+       unsigned int pending;
        unsigned long flags;
-       int pending;
 
        debug_fence_assert(fence);
        might_sleep_if(gfpflags_allow_blocking(gfp));
@@ -349,7 +354,7 @@ static int __i915_sw_fence_await_sw_fence(struct i915_sw_fence *fence,
        if (unlikely(i915_sw_fence_check_if_after(fence, signaler)))
                return -EINVAL;
 
-       pending = 0;
+       pending = I915_SW_FENCE_FLAG_FENCE;
        if (!wq) {
                wq = kmalloc(sizeof(*wq), gfp);
                if (!wq) {