arm64: smp: Defer RCU registration during secondary CPU bringup

Calling rcutree_report_cpu_starting() early during boot can lead to
livelocks with the generic CPU hotplug mechanism if the boot CPU blocks
on an RCU grace period while the CPU being onlined is spinning in
cpuhp_ap_sync_alive().

In preparation for enabling the generic CPU hotplug code on arm64, split
up the trace_hardirqs_off() call during secondary CPU bringup so that we
update lockdep early but defer the tracing updates until after the new
CPU has been registered with RCU, which itself is deferred until after
the early CPU compatibility checks, allowing us to drop the explicit
call to rcutree_report_cpu_dead() entirely.

Signed-off-by: Will Deacon <will@kernel.org>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

0 files changed, 0 insertions, 0 deletions