these hooks are required by the following features:
1.For rwsem readers, currently only the latest reader will be
recorded in sem->owner. We add hooks to record all readers which
have acquired the lock, once there are UX threads blocked in the
rwsem waiting list, these read_owners will be given high
priority in scheduling.
2.For rwsem writer, when a writer acquires the lock, we check
whether there are UX threads blocked in the rwsem wait list. If
so, we give this writer a high priority in scheduling so that it
can release the lock as soon as possible.
Both of these features can optimize the priority inversion
problem caused by rwsem and improve system responsiveness and
performance.
There is already a hook android_vh_rwsem_set_owner in rwsem_set_owner() to record writer owned, so the hook android_vh_record_rwsem_writer_owned in cherry pick is removed.
Bug: 335408185
Change-Id: I82a6fbb6acd2ce05d049e686b61e34e4d3b39a5e
Signed-off-by: zhujingpeng <zhujingpeng@vivo.com>
[jstultz: Rebased and resolved minor conflict]
Signed-off-by: John Stultz <jstultz@google.com>
(cherry picked from commit 188c41744ddcccef6daf6dcd4d6a444dabdc2f94)
(cherry picked from commit 869fc79d3abf1a1bcd97925fa3e0ee7188bb737c)
