diff options
| -rw-r--r-- | include/linux/ftrace.h | 6 | ||||
| -rw-r--r-- | kernel/trace/trace_stack.c | 32 |
2 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ef7123219f14..7b4e6572ab21 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -286,6 +286,12 @@ int stack_trace_sysctl(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); + +void stack_tracer_disable(void); +void stack_tracer_enable(void); +#else +static inline void stack_tracer_disable(void) { } +static inline void stack_tracer_enable(void) { } #endif struct ftrace_func_command { diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 338d076a06da..21e536cf66e4 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -41,6 +41,38 @@ static DEFINE_MUTEX(stack_sysctl_mutex); int stack_tracer_enabled; static int last_stack_tracer_enabled; +/** + * stack_tracer_disable - temporarily disable the stack tracer + * + * There's a few locations (namely in RCU) where stack tracing + * cannot be executed. This function is used to disable stack + * tracing during those critical sections. + * + * This function must be called with preemption or interrupts + * disabled and stack_tracer_enable() must be called shortly after + * while preemption or interrupts are still disabled. + */ +void stack_tracer_disable(void) +{ + /* Preemption or interupts must be disabled */ + if (IS_ENABLED(CONFIG_PREEMPT_DEBUG)) + WARN_ON_ONCE(!preempt_count() || !irqs_disabled()); + this_cpu_inc(trace_active); +} + +/** + * stack_tracer_enable - re-enable the stack tracer + * + * After stack_tracer_disable() is called, stack_tracer_enable() + * must be called shortly afterward. + */ +void stack_tracer_enable(void) +{ + if (IS_ENABLED(CONFIG_PREEMPT_DEBUG)) + WARN_ON_ONCE(!preempt_count() || !irqs_disabled()); + this_cpu_dec(trace_active); +} + void stack_trace_print(void) { long i; |