watchdog: implement error handling for failure to set up hardware perf events

	__this_cpu_write(soft_lockup_hrtimer_cnt,

			 __this_cpu_read(hrtimer_interrupts));

	__touch_watchdog();

	/*

	 * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the

	 * failure path. Check for failures that can occur asynchronously -

	 * for example, when CPUs are on-lined - and shut down the hardware

	 * perf event on each CPU accordingly.

	 *

	 * The only non-obvious place this bit can be cleared is through

	 * watchdog_nmi_enable(), so a pr_info() is placed there.  Placing a

	 * pr_info here would be too noisy as it would result in a message

	 * every few seconds if the hardlockup was disabled but the softlockup

	 * enabled.

	 */

	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))

		watchdog_nmi_disable(cpu);

}

#ifdef CONFIG_HARDLOCKUP_DETECTOR

		goto out_save;

	}

	/*

	 * Disable the hard lockup detector if _any_ CPU fails to set up

	 * set up the hardware perf event. The watchdog() function checks

	 * the NMI_WATCHDOG_ENABLED bit periodically.

	 *

	 * The barriers are for syncing up watchdog_enabled across all the

	 * cpus, as clear_bit() does not use barriers.

	 */

	smp_mb__before_atomic();

	clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled);

	smp_mb__after_atomic();

	/* skip displaying the same error again */

	if (cpu > 0 && (PTR_ERR(event) == cpu0_err))

		return PTR_ERR(event);

	else

		pr_err("disabled (cpu%i): unable to create perf event: %ld\n",

			cpu, PTR_ERR(event));

	pr_info("Shutting down hard lockup detector on all cpus\n");

	return PTR_ERR(event);

	/* success path */