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authorSteven Rostedt <srostedt@redhat.com>2008-11-05 16:05:44 -0500
committerIngo Molnar <mingo@elte.hu>2008-11-06 07:50:51 +0100
commit60a7ecf42661f2b22168751298592da6ee210c9e (patch)
tree050fd052c546c92f8aac10ee71d5bb6d98a21fc8 /include/linux/ftrace.h
parent79c81d220c8e25163f56edcdfaf23f83a4c88e6b (diff)
ftrace: add quick function trace stop
Impact: quick start and stop of function tracer This patch adds a way to disable the function tracer quickly without the need to run kstop_machine. It adds a new variable called function_trace_stop which will stop the calls to functions from mcount when set. This is just an on/off switch and does not handle recursion like preempt_disable(). It's main purpose is to help other tracers/debuggers start and stop tracing fuctions without the need to call kstop_machine. The config option HAVE_FUNCTION_TRACE_MCOUNT_TEST is added for archs that implement the testing of the function_trace_stop in the mcount arch dependent code. Otherwise, the test is done in the C code. x86 is the only arch at the moment that supports this. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/ftrace.h')
-rw-r--r--include/linux/ftrace.h30
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 4642959e5bd..794ab907dbf 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -23,6 +23,34 @@ struct ftrace_ops {
struct ftrace_ops *next;
};
+extern int function_trace_stop;
+
+/**
+ * ftrace_stop - stop function tracer.
+ *
+ * A quick way to stop the function tracer. Note this an on off switch,
+ * it is not something that is recursive like preempt_disable.
+ * This does not disable the calling of mcount, it only stops the
+ * calling of functions from mcount.
+ */
+static inline void ftrace_stop(void)
+{
+ function_trace_stop = 1;
+}
+
+/**
+ * ftrace_start - start the function tracer.
+ *
+ * This function is the inverse of ftrace_stop. This does not enable
+ * the function tracing if the function tracer is disabled. This only
+ * sets the function tracer flag to continue calling the functions
+ * from mcount.
+ */
+static inline void ftrace_start(void)
+{
+ function_trace_stop = 0;
+}
+
/*
* The ftrace_ops must be a static and should also
* be read_mostly. These functions do modify read_mostly variables
@@ -41,6 +69,8 @@ extern void ftrace_stub(unsigned long a0, unsigned long a1);
# define unregister_ftrace_function(ops) do { } while (0)
# define clear_ftrace_function(ops) do { } while (0)
static inline void ftrace_kill(void) { }
+static inline void ftrace_stop(void) { }
+static inline void ftrace_start(void) { }
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_DYNAMIC_FTRACE