When a compute unit issues several requests to the same line,
the requests wait in the L2 if it is a writeback cache. If the line is
invalid initially and the first request is atomic in nature, the L2
cache issues a request to main memory. On data return, the cache line
transitions to M but doesn't wake up the other requests, resulting in
a deadlock. This commit adds a wakeup call on data return for atomics
and fixes potential deadlocks.
be0a7937c1