From 7a5c8b57cec93196b3e84e3cad2ff81ae0faed78 Mon Sep 17 00:00:00 2001 From: Babu Moger Date: Wed, 14 Dec 2016 15:06:28 -0800 Subject: [PATCH] sparc: implement watchdog_nmi_enable and watchdog_nmi_disable Implement functions watchdog_nmi_enable and watchdog_nmi_disable to enable/disable nmi watchdog. Sparc uses arch specific nmi watchdog handler. Currently, we do not have a way to enable/disable nmi watchdog dynamically. With these patches we can enable or disable arch specific nmi watchdogs using proc or sysctl interface. Example commands. To enable: echo 1 > /proc/sys/kernel/nmi_watchdog To disable: echo 0 > /proc/sys/kernel/nmi_watchdog It can also achieved using the sysctl parameter kernel.nmi_watchdog Link: http://lkml.kernel.org/r/1478034826-43888-4-git-send-email-babu.moger@oracle.com Signed-off-by: Babu Moger Acked-by: Don Zickus Cc: Ingo Molnar Cc: Jiri Kosina Cc: Andi Kleen Cc: Yaowei Bai Cc: Aaron Tomlin Cc: Ulrich Obergfell Cc: Tejun Heo Cc: Hidehiro Kawai Cc: Josh Hunt Cc: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/sparc/kernel/nmi.c | 44 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/arch/sparc/kernel/nmi.c b/arch/sparc/kernel/nmi.c index a9973bb4a1b2..95e73c63c99d 100644 --- a/arch/sparc/kernel/nmi.c +++ b/arch/sparc/kernel/nmi.c @@ -42,7 +42,7 @@ static int panic_on_timeout; */ atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ EXPORT_SYMBOL(nmi_active); - +static int nmi_init_done; static unsigned int nmi_hz = HZ; static DEFINE_PER_CPU(short, wd_enabled); static int endflag __initdata; @@ -153,6 +153,8 @@ static void report_broken_nmi(int cpu, int *prev_nmi_count) void stop_nmi_watchdog(void *unused) { + if (!__this_cpu_read(wd_enabled)) + return; pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable); __this_cpu_write(wd_enabled, 0); atomic_dec(&nmi_active); @@ -207,6 +209,9 @@ error: void start_nmi_watchdog(void *unused) { + if (__this_cpu_read(wd_enabled)) + return; + __this_cpu_write(wd_enabled, 1); atomic_inc(&nmi_active); @@ -259,6 +264,8 @@ int __init nmi_init(void) } } + nmi_init_done = 1; + return err; } @@ -270,3 +277,38 @@ static int __init setup_nmi_watchdog(char *str) return 0; } __setup("nmi_watchdog=", setup_nmi_watchdog); + +/* + * sparc specific NMI watchdog enable function. + * Enables watchdog if it is not enabled already. + */ +int watchdog_nmi_enable(unsigned int cpu) +{ + if (atomic_read(&nmi_active) == -1) { + pr_warn("NMI watchdog cannot be enabled or disabled\n"); + return -1; + } + + /* + * watchdog thread could start even before nmi_init is called. + * Just Return in that case. Let nmi_init finish the init + * process first. + */ + if (!nmi_init_done) + return 0; + + smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1); + + return 0; +} +/* + * sparc specific NMI watchdog disable function. + * Disables watchdog if it is not disabled already. + */ +void watchdog_nmi_disable(unsigned int cpu) +{ + if (atomic_read(&nmi_active) == -1) + pr_warn_once("NMI watchdog cannot be enabled or disabled\n"); + else + smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1); +}