Unless cpu0 code explicitly calls do_idle(), then it never will,
and thus any on_cpu(0, ...) calls will hang. Let's assume that
if cpu0 hasn't already called do_idle() that the on_cpu(0, ...)
call from a secondary CPU was a programming error and assert.
However, it's possible the developer intends cpu0 to call do_idle
later, so give the developer a chance to disable the assert too.
Also, while cpu0 is special, it's not that special. It shouldn't
be the only CPU that can call on_cpus().
Finally, let's not mess with cpu0's idle state in on_cpus(), as
this could potentially confuse another CPU that's checking it.
Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
---
lib/arm/asm/smp.h | 2 ++
lib/arm/smp.c | 16 +++++++++++-----
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/lib/arm/asm/smp.h b/lib/arm/asm/smp.h
index 4272e0fd9253..62d14b07bc51 100644
--- a/lib/arm/asm/smp.h
+++ b/lib/arm/asm/smp.h
@@ -10,6 +10,8 @@
#define smp_processor_id() (current_thread_info()->cpu)
+extern bool cpu0_calls_idle;
+
extern void halt(void);
extern void do_idle(void);
diff --git a/lib/arm/smp.c b/lib/arm/smp.c
index 7e3c91ce3b48..b4b43237e32e 100644
--- a/lib/arm/smp.c
+++ b/lib/arm/smp.c
@@ -14,6 +14,8 @@
#include <asm/psci.h>
#include <asm/smp.h>
+bool cpu0_calls_idle;
+
cpumask_t cpu_present_mask;
cpumask_t cpu_online_mask;
cpumask_t cpu_idle_mask;
@@ -81,6 +83,9 @@ void do_idle(void)
{
int cpu = smp_processor_id();
+ if (cpu == 0)
+ cpu0_calls_idle = true;
+
set_cpu_idle(cpu, true);
sev();
@@ -103,6 +108,9 @@ void on_cpu_async(int cpu, void (*func)(void *data), void *data)
return;
}
+ assert_msg(cpu != 0 || cpu0_calls_idle, "Waiting on CPU0, which is unlikely to idle. "
+ "If this is intended set cpu0_calls_idle=1");
+
spin_lock(&lock);
if (!cpu_online(cpu))
__smp_boot_secondary(cpu, do_idle);
@@ -133,17 +141,15 @@ void on_cpu(int cpu, void (*func)(void *data), void *data)
void on_cpus(void (*func)(void))
{
- int cpu;
+ int cpu, me = smp_processor_id();
for_each_present_cpu(cpu) {
- if (cpu == 0)
+ if (cpu == me)
continue;
on_cpu_async(cpu, (on_cpu_func)func, NULL);
}
func();
- set_cpu_idle(0, true);
- while (!cpumask_full(&cpu_idle_mask))
+ while (cpumask_weight(&cpu_idle_mask) < nr_cpus - 1)
wfe();
- set_cpu_idle(0, false);
}
--
2.9.4
