Hi, Chris,
On 8/26/20 3:28 PM, 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>
---
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 4cd2038cbe35..4e557d1c4644 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)
Not sure if sharing the flags field with the wait.c implementation is
fully OK either. Is the @key parameter to the wake function useable? I
mean rather than passing just a list head could we pass something like
struct i915_sw_fence_key {
bool no_recursion; /* Makes the wait function just put its entry on
@continuation and return */
int error;
struct list_head continuation;
}
/Thomas
+
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) {
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