[PATCH 0/2] riscv: Fix cpu hotplug warnings

[Rui Qi]

This series fixes two issues with CPU hotplug on RISC-V that cause
spurious warnings when offlining CPUs.

Patch 1 fixes the immediate regression from commit 2b2b207e1162
("riscv: cpu_ops: Change return value type of cpu_is_stopped() to bool")
where the inverted warning condition triggers even when the
cpu_is_stopped callback is absent.

Patch 2 addresses the underlying race between the dying CPU and the
controlling CPU: the AP reports itself dead before it actually invokes
cpu_stop(), so the BP can observe the SBI HSM state as STARTED rather
than STOPPED. This was previously masked by the old semantics where
SBI_HSM_STATE_STARTED (0) was treated as success. The fix adds polling
with read_poll_timeout(), following the same approach as arm64's
cpu_psci_cpu_kill().

Rui Qi (2):
  riscv: Fix spurious warning when cpu_is_stopped callback is absent
  riscv: Poll for SBI_HSM_STATE_STOPPED in sbi_cpu_is_stopped()

 arch/riscv/kernel/cpu-hotplug.c |  6 +-----
 arch/riscv/kernel/cpu_ops_sbi.c | 13 ++++++++++---
 2 files changed, 11 insertions(+), 8 deletions(-)

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2.20.1