[PATCH 08/13] arm64: Use cpu_ops for smp_stop

Geoff Levand
2014-09-09T22:49:05Z

The current implementation of ipi_cpu_stop() is just a tight infinite loop
around cpu_relax(). This infinite loop implementation is OK if the machine
will soon do a poweroff, but it doesn't have any mechanism to allow a CPU
to be brought back on-line, nor is it compatible with kexec re-boot.

Add a check for a valid cpu_die method of the appropriate cpu_ops structure,
and if a valid method is found, transfer control to that method. It is
expected that the cpu_die method puts the CPU into a state such that they can
be brought back on-line or progress through a kexec re-boot.

Signed-off-by: Geoff Levand <geoff@infradead.org>
---
arch/arm64/kernel/smp.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 4743397..002aa8a 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -555,6 +555,15 @@ static void ipi_cpu_stop(unsigned int cpu)

local_irq_disable();

+ /* If we have the cpu ops use them. */
+
+ if (cpu_ops[cpu]->cpu_disable &&
+ cpu_ops[cpu]->cpu_die &&
+ !cpu_ops[cpu]->cpu_disable(cpu))
+ cpu_ops[cpu]->cpu_die(cpu);
+
+ /* Otherwise spin here. */
+
while (1)
cpu_relax();
}
--
1.9.1