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Subject[PATCH 08/13] ftrace: Have global_ops store the functions that are to be traced
From: Steven Rostedt <srostedt@redhat.com>

This is a step towards each ops structure defining its own set
of functions to trace. As the current code with pid's and such
are specific to the global_ops, it is restructured to be used
with the global ops.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 69 +++++++++++++++++++++++++++++++++++++-----------
1 files changed, 53 insertions(+), 16 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8fef1d9..dcce0bf 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -91,6 +91,7 @@ static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;
+static struct ftrace_ops global_ops;

/*
* Traverse the ftrace_list, invoking all entries. The reason that we
@@ -153,7 +154,7 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
}
#endif

-static void update_ftrace_function(void)
+static void update_global_ops(void)
{
ftrace_func_t func;

@@ -173,6 +174,18 @@ static void update_ftrace_function(void)
set_ftrace_pid_function(func);
func = ftrace_pid_func;
}
+
+ global_ops.func = func;
+}
+
+static void update_ftrace_function(void)
+{
+ ftrace_func_t func;
+
+ update_global_ops();
+
+ func = global_ops.func;
+
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
ftrace_trace_function = func;
#else
@@ -181,24 +194,19 @@ static void update_ftrace_function(void)
#endif
}

-static int __register_ftrace_function(struct ftrace_ops *ops)
+static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
- ops->next = ftrace_list;
+ ops->next = *list;
/*
* We are entering ops into the ftrace_list but another
* CPU might be walking that list. We need to make sure
* the ops->next pointer is valid before another CPU sees
* the ops pointer included into the ftrace_list.
*/
- rcu_assign_pointer(ftrace_list, ops);
-
- if (ftrace_enabled)
- update_ftrace_function();
-
- return 0;
+ rcu_assign_pointer(*list, ops);
}

-static int __unregister_ftrace_function(struct ftrace_ops *ops)
+static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
struct ftrace_ops **p;

@@ -206,13 +214,12 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
* If we are removing the last function, then simply point
* to the ftrace_stub.
*/
- if (ftrace_list == ops && ops->next == &ftrace_list_end) {
- ftrace_trace_function = ftrace_stub;
- ftrace_list = &ftrace_list_end;
+ if (*list == ops && ops->next == &ftrace_list_end) {
+ *list = &ftrace_list_end;
return 0;
}

- for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
+ for (p = list; *p != &ftrace_list_end; p = &(*p)->next)
if (*p == ops)
break;

@@ -220,7 +227,37 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
return -1;

*p = (*p)->next;
+ return 0;
+}
+
+static int __register_ftrace_function(struct ftrace_ops *ops)
+{
+ if (ftrace_disabled)
+ return -ENODEV;
+
+ if (FTRACE_WARN_ON(ops == &global_ops))
+ return -EINVAL;
+
+ add_ftrace_ops(&ftrace_list, ops);
+ if (ftrace_enabled)
+ update_ftrace_function();
+
+ return 0;
+}

+static int __unregister_ftrace_function(struct ftrace_ops *ops)
+{
+ int ret;
+
+ if (ftrace_disabled)
+ return -ENODEV;
+
+ if (FTRACE_WARN_ON(ops == &global_ops))
+ return -EINVAL;
+
+ ret = remove_ftrace_ops(&ftrace_list, ops);
+ if (ret < 0)
+ return ret;
if (ftrace_enabled)
update_ftrace_function();

@@ -894,7 +931,7 @@ enum {
FTRACE_OPS_FL_ENABLED = 1,
};

-struct ftrace_ops global_ops = {
+static struct ftrace_ops global_ops = {
.func = ftrace_stub,
.notrace_hash = EMPTY_HASH,
.filter_hash = EMPTY_HASH,
@@ -3263,7 +3300,7 @@ void __init ftrace_init(void)

#else

-struct ftrace_ops global_ops = {
+static struct ftrace_ops global_ops = {
.func = ftrace_stub,
};

--
1.7.4.4



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