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-rw-r--r--include/linux/ftrace.h36
1 files changed, 34 insertions, 2 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 7b4e6572ab21..06b2990a35e4 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -287,8 +287,40 @@ 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);
+/* DO NOT MODIFY THIS VARIABLE DIRECTLY! */
+DECLARE_PER_CPU(int, disable_stack_tracer);
+
+/**
+ * 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.
+ */
+static inline 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(disable_stack_tracer);
+}
+
+/**
+ * stack_tracer_enable - re-enable the stack tracer
+ *
+ * After stack_tracer_disable() is called, stack_tracer_enable()
+ * must be called shortly afterward.
+ */
+static inline void stack_tracer_enable(void)
+{
+ if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
+ WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
+ this_cpu_dec(disable_stack_tracer);
+}
#else
static inline void stack_tracer_disable(void) { }
static inline void stack_tracer_enable(void) { }