Commit 39f152ff authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
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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: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarBorislav 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4d7b02d5

arch/x86/kernel/cpu/mcheck/mce.c

+20 −16
Original line number Diff line number Diff line
@@ -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;

	}

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