Since upstream commit 617f3ef951 ("locking/rwsem: Remove
reader optimistic spinning"), vendors have seen increased
contention and blocking on rwsems.
There are attempts to actively fix this upstream:
https://lore.kernel.org/lkml/20240406081126.8030-1-bongkyu7.kim@samsung.com/
But in the meantime, provide vendorhooks so that vendors can
implement their own optimistic spin routine. In doing so,
vendors see improvements in cold launch times on important apps.
Bug: 331742151
Change-Id: I7466413de9ee1293e86f73880931235d7a9142ac
Signed-off-by: xieliujie <xieliujie@oppo.com>
[jstultz: Rewrote commit message]
Signed-off-by: John Stultz <jstultz@google.com>
260bfad693