On Mon, Dec 07, 2020 at 07:38:17PM +0000, Chris Wilson wrote:
> 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@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_sw_fence.c | 25 +++++++++++++++----------
> 1 file changed, 15 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
> index 038d4c6884c5..2744558f3050 100644
> --- 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) {
> --
> 2.20.1
>
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
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