x86/mcheck: Reorganize the hotplug callbacks

Initially I wanted to remove mcheck_cpu_init() from identify_cpu() and let it
become an independent early hotplug callback. The main problem here was that
the init on the boot CPU may happen too late
(device_initcall_sync(mcheck_init_device)) and nobody wanted to risk receiving
and MCE event at boot time leading to a shutdown (if the MCE feature is not yet
enabled).

Here is attempt two: the timming stays as-is but the ordering of the functions
is changed:
- mcheck_cpu_init() (which is run from identify_cpu()) will setup the timer
  struct but won't fire the timer. This is moved to CPU_ONLINE since its
  cleanup part is in CPU_DOWN_PREPARE. So if it is okay to stop the timer early
  in the shutdown phase, it should be okay to start it late in the bring up phase.

- CPU_DOWN_PREPARE disables the MCE feature flags for !INTEL CPUs in
  mce_disable_cpu(). If a failure occures it would be re-enabled on all vendor
  CPUs (including Intel where it was not disabled during shutdown). To keep this
  working I am moving it to CPU_ONLINE. smp_call_function_single() is dropped
  beause the notifier runs nowdays on the target CPU.

- CPU_ONLINE is invoking mce_device_create() + mce_threshold_create_device()
  but its cleanup part is in CPU_DEAD (mce_threshold_remove_device() and
  mce_device_remove()). In order to keep this symmetrical I am moving the clean
  up from CPU_DEAD to CPU_DOWN_PREPARE.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: rt@linutronix.de
Cc: linux-edac@vger.kernel.org
Link: http://lkml.kernel.org/r/20161110174447.11848-6-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 20 insertions, 16 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 052b5e05c3c4..a524faa51400 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1745,6 +1745,14 @@ static void mce_start_timer(unsigned int cpu, struct timer_list *t)
         add_timer_on(t, cpu);
 }
 
+static void __mcheck_cpu_setup_timer(void)
+{
+        struct timer_list *t = this_cpu_ptr(&mce_timer);
+        unsigned int cpu = smp_processor_id();
+
+        setup_pinned_timer(t, mce_timer_fn, cpu);
+}
+
 static void __mcheck_cpu_init_timer(void)
 {
         struct timer_list *t = this_cpu_ptr(&mce_timer);
@@ -1796,7 +1804,7 @@ void mcheck_cpu_init(struct cpuinfo_x86 *c)
         __mcheck_cpu_init_generic();
         __mcheck_cpu_init_vendor(c);
         __mcheck_cpu_init_clear_banks();
-        __mcheck_cpu_init_timer();
+        __mcheck_cpu_setup_timer();
 }
 
 /*
@@ -2470,28 +2478,25 @@ static void mce_device_remove(unsigned int cpu)
 }
 
 /* Make sure there are no machine checks on offlined CPUs. */
-static void mce_disable_cpu(void *h)
+static void mce_disable_cpu(void)
 {
-        unsigned long action = *(unsigned long *)h;
-
         if (!mce_available(raw_cpu_ptr(&cpu_info)))
                 return;
 
-        if (!(action & CPU_TASKS_FROZEN))
+        if (!cpuhp_tasks_frozen)
                 cmci_clear();
 
         vendor_disable_error_reporting();
 }
 
-static void mce_reenable_cpu(void *h)
+static void mce_reenable_cpu(void)
 {
-        unsigned long action = *(unsigned long *)h;
         int i;
 
         if (!mce_available(raw_cpu_ptr(&cpu_info)))
                 return;
 
-        if (!(action & CPU_TASKS_FROZEN))
+        if (!cpuhp_tasks_frozen)
                 cmci_reenable();
         for (i = 0; i < mca_cfg.banks; i++) {
                 struct mce_bank *b = &mce_banks[i];
@@ -2510,6 +2515,7 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 
         switch (action & ~CPU_TASKS_FROZEN) {
         case CPU_ONLINE:
+        case CPU_DOWN_FAILED:
 
                 mce_device_create(cpu);
 
@@ -2517,11 +2523,10 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
                         mce_device_remove(cpu);
                         return NOTIFY_BAD;
                 }
-
+                mce_reenable_cpu();
+                mce_start_timer(cpu, t);
                 break;
         case CPU_DEAD:
-                mce_threshold_remove_device(cpu);
-                mce_device_remove(cpu);
                 mce_intel_hcpu_update(cpu);
 
                 /* intentionally ignoring frozen here */
@@ -2529,12 +2534,11 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
                         cmci_rediscover();
                 break;
         case CPU_DOWN_PREPARE:
-                smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
+                mce_disable_cpu();
                 del_timer_sync(t);
-                break;
-        case CPU_DOWN_FAILED:
-                smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
-                mce_start_timer(cpu, t);
+
+                mce_threshold_remove_device(cpu);
+                mce_device_remove(cpu);
                 break;
         }