Commit f5e74e83 authored by Laurent Dufour's avatar Laurent Dufour Committed by Michael Ellerman
Browse files

powerpc/watchdog: introduce a NMI watchdog's factor 



Introduce a factor which would apply to the NMI watchdog timeout.

This factor is a percentage added to the watchdog_tresh value. The value is
set under the watchdog_mutex protection and lockup_detector_reconfigure()
is called to recompute wd_panic_timeout_tb.

Once the factor is set, it remains until it is set back to 0, which means
no impact.

Signed-off-by: default avatarLaurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220713154729.80789-4-ldufour@linux.ibm.com
parent 7c56a873

arch/powerpc/include/asm/nmi.h

+2 −0
Original line number Diff line number Diff line
@@ -5,8 +5,10 @@ 
#ifdef CONFIG_PPC_WATCHDOG

extern void arch_touch_nmi_watchdog(void);

long soft_nmi_interrupt(struct pt_regs *regs);

void watchdog_nmi_set_timeout_pct(u64 pct);

#else

static inline void arch_touch_nmi_watchdog(void) {}

static inline void watchdog_nmi_set_timeout_pct(u64 pct) {}

#endif



#ifdef CONFIG_NMI_IPI

arch/powerpc/kernel/watchdog.c

+20 −1
Original line number Diff line number Diff line
@@ -91,6 +91,10 @@ static cpumask_t wd_smp_cpus_pending; 
static cpumask_t wd_smp_cpus_stuck;

static u64 wd_smp_last_reset_tb;



#ifdef CONFIG_PPC_PSERIES

static u64 wd_timeout_pct;

#endif



/*

 * Try to take the exclusive watchdog action / NMI IPI / printing lock.

 * wd_smp_lock must be held. If this fails, we should return and wait
@@ -527,7 +531,13 @@ static int stop_watchdog_on_cpu(unsigned int cpu) 


static void watchdog_calc_timeouts(void)

{

	wd_panic_timeout_tb = watchdog_thresh * ppc_tb_freq;

	u64 threshold = watchdog_thresh;



#ifdef CONFIG_PPC_PSERIES

	threshold += (READ_ONCE(wd_timeout_pct) * threshold) / 100;

#endif



	wd_panic_timeout_tb = threshold * ppc_tb_freq;



	/* Have the SMP detector trigger a bit later */

	wd_smp_panic_timeout_tb = wd_panic_timeout_tb * 3 / 2;
@@ -570,3 +580,12 @@ int __init watchdog_nmi_probe(void) 
	}

	return 0;

}



#ifdef CONFIG_PPC_PSERIES

void watchdog_nmi_set_timeout_pct(u64 pct)

{

	pr_info("Set the NMI watchdog timeout factor to %llu%%\n", pct);

	WRITE_ONCE(wd_timeout_pct, pct);

	lockup_detector_reconfigure();

}

#endif