On Mon, Nov 30, 2015 at 05:36:40PM -0500, Steven Rostedt wrote:
>
> [ Jiri, can you take a look at this. You can also apply it on top of my
> branch ftrace/core, and run any specific tests. I just need to nuke
> that control structure for further updates with ftrace. ]
>
>
> Currently perf has its own list function within the ftrace infrastructure
> that seems to be used only to allow for it to have per-cpu disabling as well
> as a check to make sure that it's not called while RCU is not watching. It
> uses something called the "control_ops" which is used to iterate over ops
> under it with the control_list_func().
>
> The problem is that this control_ops and control_list_func unnecessarily
> complicates the code. By replacing FTRACE_OPS_FL_CONTROL with two new flags
> (FTRACE_OPS_FL_RCU and FTRACE_OPS_FL_PER_CPU) we can remove all the code
> that is special with the control ops and add the needed checks within the
> generic ftrace_list_func().
hum,
do we need also change for the trampoline, something like below?
I needed attached patch to get the perf ftrace:function
event work properly..
thanks,
jirka
---
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index c4d881200d1f..2705ac2f3487 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5179,6 +5179,26 @@ static void ftrace_ops_recurs_func(unsigned long ip,
unsigned long parent_ip,
trace_clear_recursion(bit);
}
+static void ftrace_ops_per_cpu_func(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *regs)
+{
+ int bit;
+
+ bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
+ if (bit < 0)
+ return;
+
+ preempt_disable_notrace();
+
+ if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) &&
+ (!(op->flags & FTRACE_OPS_FL_PER_CPU) ||
!ftrace_function_local_disabled(op))) {
+ op->func(ip, parent_ip, op, regs);
+ }
+
+ preempt_enable_notrace();
+ trace_clear_recursion(bit);
+}
+
/**
* ftrace_ops_get_func - get the function a trampoline should call
* @ops: the ops to get the function for
@@ -5192,6 +5212,11 @@ static void ftrace_ops_recurs_func(unsigned long ip,
unsigned long parent_ip,
*/
ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops)
{
+ if (ops->flags & (FTRACE_OPS_FL_PER_CPU|FTRACE_OPS_FL_RCU)) {
+ printk("used per cpu trampoline function\n");
+ return ftrace_ops_per_cpu_func;
+ }
+
/*
* If the func handles its own recursion, call it directly.
* Otherwise call the recursion protected function that
--
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