On 9/3/20 1:32 PM, Chris Wilson wrote:
Quoting Thomas Hellström (Intel) (2020-09-03 10:50:45)
On 9/2/20 4:02 PM, Thomas Hellström (Intel) wrote:
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;
}
That would mean wait_event-esque routines do not work on a fence.
OK, that is a no-go then.
internal wake function instead of the autoremove_wake_function remove
the fragility. Would that be possible?
autoremove is the function used by display for its wait_event loop over
multiple sources.
Hmm. I don't think I follow. I meant instead of
if (pos->func == autoremove_wake_function)
...
else
do_i915_specific_stuff;
we use
if (pos->func != i915_sw_fence_wake)
...
else
do_i915_specific_stuff;
/Thomas
-Chris
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