ARM: imx: fix sync issue between imx_cpu_die and imx_cpu_kill
There is a sync issue with hotplug operation. It's possible that when
imx_cpu_kill gets running on primary core, the imx_cpu_die execution
on the core which is to be killed hasn't been finished yet. The problem
will very likely be hit when running suspend without no_console_suspend
setting on kernel cmdline.
It uses cpu jumping argument register to sync imx_cpu_die and
imx_cpu_kill. The register will be set in imx_cpu_die and imx_cpu_kill
will wait for the register being cleared to actually kill the cpu.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: <stable@vger.kernel.org>
diff --git a/arch/arm/mach-imx/hotplug.c b/arch/arm/mach-imx/hotplug.c
index 7bc5fe1..361a253 100644
--- a/arch/arm/mach-imx/hotplug.c
+++ b/arch/arm/mach-imx/hotplug.c
@@ -46,11 +46,23 @@
void imx_cpu_die(unsigned int cpu)
{
cpu_enter_lowpower();
+ /*
+ * We use the cpu jumping argument register to sync with
+ * imx_cpu_kill() which is running on cpu0 and waiting for
+ * the register being cleared to kill the cpu.
+ */
+ imx_set_cpu_arg(cpu, ~0);
cpu_do_idle();
}
int imx_cpu_kill(unsigned int cpu)
{
+ unsigned long timeout = jiffies + msecs_to_jiffies(50);
+
+ while (imx_get_cpu_arg(cpu) == 0)
+ if (time_after(jiffies, timeout))
+ return 0;
imx_enable_cpu(cpu, false);
+ imx_set_cpu_arg(cpu, 0);
return 1;
}