From de7edd31457b626e54a0b2a7e8ff4d65492f01ad Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 14 Jun 2013 16:21:43 -0400 Subject: tracing: Disable tracing on warning Add a traceoff_on_warning option in both the kernel command line as well as a sysctl option. When set, any WARN*() function that is hit will cause the tracing_on variable to be cleared, which disables writing to the ring buffer. This is useful especially when tracing a bug with function tracing. When a warning is hit, the print caused by the warning can flood the trace with the functions that producing the output for the warning. This can make the resulting trace useless by either hiding where the bug happened, or worse, by overflowing the buffer and losing the trace of the bug totally. Acked-by: Peter Zijlstra Signed-off-by: Steven Rostedt --- kernel/sysctl.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 9edcf456e0f..5b0f18c1280 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -600,6 +600,13 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "traceoff_on_warning", + .data = &__disable_trace_on_warning, + .maxlen = sizeof(__disable_trace_on_warning), + .mode = 0644, + .proc_handler = proc_dointvec, + }, #endif #ifdef CONFIG_MODULES { -- cgit v1.2.3-70-g09d2 From 3c00ea82c724fab0b98f15428a804cb45eb9ad38 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sun, 19 May 2013 20:45:15 +0200 Subject: watchdog: Rename confusing state variable We have two very conflicting state variable names in the watchdog: * watchdog_enabled: This one reflects the user interface. It's set to 1 by default and can be overriden with boot options or sysctl/procfs interface. * watchdog_disabled: This is the internal toggle state that tells if watchdog threads, timers and NMI events are currently running or not. This state mostly depends on the user settings. It's a convenient state latch. Now we really need to find clearer names because those are just too confusing to encourage deep review. watchdog_enabled now becomes watchdog_user_enabled to reflect its purpose as an interface. watchdog_disabled becomes watchdog_running to suggest its role as a pure internal state. Signed-off-by: Frederic Weisbecker Cc: Srivatsa S. Bhat Cc: Anish Singh Cc: Steven Rostedt Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Li Zhong Cc: Don Zickus --- include/linux/nmi.h | 2 +- kernel/sysctl.c | 4 ++-- kernel/watchdog.c | 30 +++++++++++++++--------------- 3 files changed, 18 insertions(+), 18 deletions(-) (limited to 'kernel/sysctl.c') diff --git a/include/linux/nmi.h b/include/linux/nmi.h index db50840e635..6a45fb583ff 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -46,7 +46,7 @@ static inline bool trigger_all_cpu_backtrace(void) #ifdef CONFIG_LOCKUP_DETECTOR int hw_nmi_is_cpu_stuck(struct pt_regs *); u64 hw_nmi_get_sample_period(int watchdog_thresh); -extern int watchdog_enabled; +extern int watchdog_user_enabled; extern int watchdog_thresh; struct ctl_table; extern int proc_dowatchdog(struct ctl_table *, int , diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 9edcf456e0f..b0805652c4f 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -801,7 +801,7 @@ static struct ctl_table kern_table[] = { #if defined(CONFIG_LOCKUP_DETECTOR) { .procname = "watchdog", - .data = &watchdog_enabled, + .data = &watchdog_user_enabled, .maxlen = sizeof (int), .mode = 0644, .proc_handler = proc_dowatchdog, @@ -828,7 +828,7 @@ static struct ctl_table kern_table[] = { }, { .procname = "nmi_watchdog", - .data = &watchdog_enabled, + .data = &watchdog_user_enabled, .maxlen = sizeof (int), .mode = 0644, .proc_handler = proc_dowatchdog, diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 52c9a9b91bd..51c4f34d258 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -29,9 +29,9 @@ #include #include -int watchdog_enabled = 1; +int watchdog_user_enabled = 1; int __read_mostly watchdog_thresh = 10; -static int __read_mostly watchdog_disabled = 1; +static int __read_mostly watchdog_running; static u64 __read_mostly sample_period; static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); @@ -63,7 +63,7 @@ static int __init hardlockup_panic_setup(char *str) else if (!strncmp(str, "nopanic", 7)) hardlockup_panic = 0; else if (!strncmp(str, "0", 1)) - watchdog_enabled = 0; + watchdog_user_enabled = 0; return 1; } __setup("nmi_watchdog=", hardlockup_panic_setup); @@ -82,7 +82,7 @@ __setup("softlockup_panic=", softlockup_panic_setup); static int __init nowatchdog_setup(char *str) { - watchdog_enabled = 0; + watchdog_user_enabled = 0; return 1; } __setup("nowatchdog", nowatchdog_setup); @@ -90,7 +90,7 @@ __setup("nowatchdog", nowatchdog_setup); /* deprecated */ static int __init nosoftlockup_setup(char *str) { - watchdog_enabled = 0; + watchdog_user_enabled = 0; return 1; } __setup("nosoftlockup", nosoftlockup_setup); @@ -158,7 +158,7 @@ void touch_all_softlockup_watchdogs(void) #ifdef CONFIG_HARDLOCKUP_DETECTOR void touch_nmi_watchdog(void) { - if (watchdog_enabled) { + if (watchdog_user_enabled) { unsigned cpu; for_each_present_cpu(cpu) { @@ -490,12 +490,12 @@ static int watchdog_enable_all_cpus(void) { int err = 0; - if (watchdog_disabled) { + if (!watchdog_running) { err = smpboot_register_percpu_thread(&watchdog_threads); if (err) pr_err("Failed to create watchdog threads, disabled\n"); else - watchdog_disabled = 0; + watchdog_running = 1; } return err; @@ -506,8 +506,8 @@ static int watchdog_enable_all_cpus(void) #ifdef CONFIG_SYSCTL static void watchdog_disable_all_cpus(void) { - if (!watchdog_disabled) { - watchdog_disabled = 1; + if (watchdog_running) { + watchdog_running = 0; smpboot_unregister_percpu_thread(&watchdog_threads); } } @@ -522,7 +522,7 @@ int proc_dowatchdog(struct ctl_table *table, int write, int err, old_thresh, old_enabled; old_thresh = ACCESS_ONCE(watchdog_thresh); - old_enabled = ACCESS_ONCE(watchdog_enabled); + old_enabled = ACCESS_ONCE(watchdog_user_enabled); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (err || !write) @@ -531,10 +531,10 @@ int proc_dowatchdog(struct ctl_table *table, int write, set_sample_period(); /* * Watchdog threads shouldn't be enabled if they are - * disabled. The 'watchdog_disabled' variable check in + * disabled. The 'watchdog_running' variable check in * watchdog_*_all_cpus() function takes care of this. */ - if (watchdog_enabled && watchdog_thresh) + if (watchdog_user_enabled && watchdog_thresh) err = watchdog_enable_all_cpus(); else watchdog_disable_all_cpus(); @@ -542,7 +542,7 @@ int proc_dowatchdog(struct ctl_table *table, int write, /* Restore old values on failure */ if (err) { watchdog_thresh = old_thresh; - watchdog_enabled = old_enabled; + watchdog_user_enabled = old_enabled; } return err; @@ -553,6 +553,6 @@ void __init lockup_detector_init(void) { set_sample_period(); - if (watchdog_enabled) + if (watchdog_user_enabled) watchdog_enable_all_cpus(); } -- cgit v1.2.3-70-g09d2