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Subject[PATCH 7/8] ftrace: Consolidate updating of ftrace_trace_function
From: Steven Rostedt <srostedt@redhat.com>

There are three locations that perform almost identical functions in order
to update the ftrace_trace_function (the ftrace function variable that gets
called by mcount).

Consolidate these into a single function called update_ftrace_function().

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 95 +++++++++++++++++-------------------------------
1 files changed, 34 insertions(+), 61 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 5b758ea..33bcc71 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -151,6 +151,34 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
}
#endif

+static void update_ftrace_function(void)
+{
+ ftrace_func_t func;
+
+ /*
+ * If there's only one function registered, then call that
+ * function directly. Otherwise, we need to iterate over the
+ * registered callers.
+ */
+ if (ftrace_list == &ftrace_list_end ||
+ ftrace_list->next == &ftrace_list_end)
+ func = ftrace_list->func;
+ else
+ func = ftrace_list_func;
+
+ /* If we filter on pids, update to use the pid function */
+ if (!list_empty(&ftrace_pids)) {
+ set_ftrace_pid_function(func);
+ func = ftrace_pid_func;
+ }
+#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
+ ftrace_trace_function = func;
+#else
+ __ftrace_trace_function = func;
+ ftrace_trace_function = ftrace_test_stop_func;
+#endif
+}
+
static int __register_ftrace_function(struct ftrace_ops *ops)
{
ops->next = ftrace_list;
@@ -162,30 +190,8 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
*/
rcu_assign_pointer(ftrace_list, ops);

- if (ftrace_enabled) {
- ftrace_func_t func;
-
- if (ops->next == &ftrace_list_end)
- func = ops->func;
- else
- func = ftrace_list_func;
-
- if (!list_empty(&ftrace_pids)) {
- set_ftrace_pid_function(func);
- func = ftrace_pid_func;
- }
-
- /*
- * For one func, simply call it directly.
- * For more than one func, call the chain.
- */
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
- ftrace_trace_function = func;
-#else
- __ftrace_trace_function = func;
- ftrace_trace_function = ftrace_test_stop_func;
-#endif
- }
+ if (ftrace_enabled)
+ update_ftrace_function();

return 0;
}
@@ -213,52 +219,19 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)

*p = (*p)->next;

- if (ftrace_enabled) {
- /* If we only have one func left, then call that directly */
- if (ftrace_list->next == &ftrace_list_end) {
- ftrace_func_t func = ftrace_list->func;
-
- if (!list_empty(&ftrace_pids)) {
- set_ftrace_pid_function(func);
- func = ftrace_pid_func;
- }
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
- ftrace_trace_function = func;
-#else
- __ftrace_trace_function = func;
-#endif
- }
- }
+ if (ftrace_enabled)
+ update_ftrace_function();

return 0;
}

static void ftrace_update_pid_func(void)
{
- ftrace_func_t func;
-
+ /* Only do something if we are tracing something */
if (ftrace_trace_function == ftrace_stub)
return;

-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
- func = ftrace_trace_function;
-#else
- func = __ftrace_trace_function;
-#endif
-
- if (!list_empty(&ftrace_pids)) {
- set_ftrace_pid_function(func);
- func = ftrace_pid_func;
- } else {
- if (func == ftrace_pid_func)
- func = ftrace_pid_function;
- }
-
-#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
- ftrace_trace_function = func;
-#else
- __ftrace_trace_function = func;
-#endif
+ update_ftrace_function();
}

#ifdef CONFIG_FUNCTION_PROFILER
--
1.7.2.3



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