Hi Michael,
On 6/5/22 05:01, Michael Ellerman wrote:
> Dmitry Osipenko <dmitry.osipe...@collabora.com> writes:
>> We're unconditionally registering sys-off handler for the legacy
>> pm_power_off() callback, this causes problem for platforms that don't
>> use power-off handlers at all and should be halted. Now reboot syscall
>> assumes that there is a power-off handler installed and tries to power
>> off system instead of halting it.
>>
>> To fix the trouble, move the handler's registration to the reboot syscall
>> and check the pm_power_off() presence.
>
> I'm seeing a qemu virtual machine (ppce500) fail to power off using the
> gpio-poweroff driver. I bisected it to this commit.
>
> I think the problem is that the machine is going via kernel_power_off(),
> not sys_reboot(), and so legacy_pm_power_off() has not been registered.
>
> If I just put the core_initcall back then it works as before. Not sure
> if that's a safe change in general though.
Thank you very much for the testing and reporting the problem! I see now the
two more cases that were missed previously:
1. There is the orderly_poweroff() used by some drivers.
2. PowerPC may invoke do_kernel_power_off() directly from xmon code.
Could you please test this change:
--- >8 ---
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 3b19b123efec..0e4a3defcd94 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -320,6 +320,7 @@ static struct sys_off_handler platform_sys_off_handler;
static struct sys_off_handler *alloc_sys_off_handler(int priority)
{
struct sys_off_handler *handler;
+ gfp_t flags;
/*
* Platforms like m68k can't allocate sys_off handler dynamically
@@ -330,7 +331,12 @@ static struct sys_off_handler *alloc_sys_off_handler(int
priority)
if (handler->cb_data)
return ERR_PTR(-EBUSY);
} else {
- handler = kzalloc(sizeof(*handler), GFP_KERNEL);
+ if (system_state > SYSTEM_RUNNING)
+ flags = GFP_ATOMIC;
+ else
+ flags = GFP_KERNEL;
+
+ handler = kzalloc(sizeof(*handler), flags);
if (!handler)
return ERR_PTR(-ENOMEM);
}
@@ -615,7 +621,26 @@ static void do_kernel_power_off_prepare(void)
*/
void do_kernel_power_off(void)
{
+ struct sys_off_handler *sys_off = NULL;
+
+ /*
+ * Register sys-off handlers for legacy PM callback. This allows
+ * legacy PM callbacks temporary co-exist with the new sys-off API.
+ *
+ * TODO: Remove legacy handlers once all legacy PM users will be
+ * switched to the sys-off based APIs.
+ */
+ if (pm_power_off) {
+ sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_DEFAULT,
+ legacy_pm_power_off, NULL);
+ if (IS_ERR(sys_off))
+ return;
+ }
+
atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
+
+ unregister_sys_off_handler(sys_off);
}
/**
@@ -626,7 +651,8 @@ void do_kernel_power_off(void)
*/
bool kernel_can_power_off(void)
{
- return !atomic_notifier_call_chain_is_empty(&power_off_handler_list);
+ return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
+ pm_power_off;
}
EXPORT_SYMBOL_GPL(kernel_can_power_off);
@@ -661,7 +687,6 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned
int, cmd,
void __user *, arg)
{
struct pid_namespace *pid_ns = task_active_pid_ns(current);
- struct sys_off_handler *sys_off = NULL;
char buffer[256];
int ret = 0;
@@ -686,21 +711,6 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned
int, cmd,
if (ret)
return ret;
- /*
- * Register sys-off handlers for legacy PM callback. This allows
- * legacy PM callbacks temporary co-exist with the new sys-off API.
- *
- * TODO: Remove legacy handlers once all legacy PM users will be
- * switched to the sys-off based APIs.
- */
- if (pm_power_off) {
- sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
- SYS_OFF_PRIO_DEFAULT,
- legacy_pm_power_off, NULL);
- if (IS_ERR(sys_off))
- return PTR_ERR(sys_off);
- }
-
/* Instead of trying to make the power_off code look like
* halt when pm_power_off is not set do it the easy way.
*/
@@ -758,7 +768,6 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned
int, cmd,
break;
}
mutex_unlock(&system_transition_mutex);
- unregister_sys_off_handler(sys_off);
return ret;
}
