On Sun, 25 Apr 2021 05:56:53 +0000
Ruifeng Wang [off-list ref] wrote:

Instead of polling for tail to be updated, use wfe instruction.

Signed-off-by: Gavin Hu <redacted>
Signed-off-by: Ruifeng Wang <redacted>
Reviewed-by: Steve Capper <redacted>
Reviewed-by: Ola Liljedahl <redacted>
Reviewed-by: Honnappa Nagarahalli <redacted>
Acked-by: Konstantin Ananyev <redacted>

Looks ok to me, but it does raise an interesting question.
Shouldn't the original code have been using atomic load to look at ht->tail.

This another place where "volatile considered harmful" applies.