Hi!
From: Marco Elver elver@google.com
[ Upstream commit f95e5a3d59011eec1257d0e76de1e1f8969d426f ]
Internal data structures (cpu_bps, task_bps) of powerpc's hw_breakpoint implementation have relied on nr_bp_mutex serializing access to them.
Before overhauling synchronization of kernel/events/hw_breakpoint.c, introduce 2 spinlocks to synchronize cpu_bps and task_bps respectively, thus avoiding reliance on callers synchronizing powerpc's hw_breakpoint.
This is preparation, not a bugfix, not sure why it was picked for 5.10.
Best regards, Pavel