From: Laurent Dufour ldufour@linux.ibm.com
[ Upstream commit f5e74e836097d1004077390717d4bd95d4a2c27a ]
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: Laurent Dufour ldufour@linux.ibm.com Reviewed-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220713154729.80789-4-ldufour@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/nmi.h | 2 ++ arch/powerpc/kernel/watchdog.c | 21 ++++++++++++++++++++- 2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/nmi.h b/arch/powerpc/include/asm/nmi.h index ea0e487f87b1..c3c7adef74de 100644 --- a/arch/powerpc/include/asm/nmi.h +++ b/arch/powerpc/include/asm/nmi.h @@ -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 diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index 7d28b9553654..5d903e63f932 100644 --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -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