ftrace: Remove use of control list and ops

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().

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 18 insertions, 17 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 134f8d45b35b..4736a826baf5 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -76,8 +76,8 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  * ENABLED - set/unset when ftrace_ops is registered/unregistered
  * DYNAMIC - set when ftrace_ops is registered to denote dynamically
  *           allocated ftrace_ops which need special care
- * CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops
- *           could be controled by following calls:
+ * PER_CPU - set manualy by ftrace_ops user to denote the ftrace_ops
+ *           could be controlled by following calls:
  *             ftrace_function_local_enable
  *             ftrace_function_local_disable
  * SAVE_REGS - The ftrace_ops wants regs saved at each function called
@@ -121,7 +121,7 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
 enum {
 	FTRACE_OPS_FL_ENABLED			= 1 << 0,
 	FTRACE_OPS_FL_DYNAMIC			= 1 << 1,
-	FTRACE_OPS_FL_CONTROL			= 1 << 2,
+	FTRACE_OPS_FL_PER_CPU			= 1 << 2,
 	FTRACE_OPS_FL_SAVE_REGS			= 1 << 3,
 	FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED	= 1 << 4,
 	FTRACE_OPS_FL_RECURSION_SAFE		= 1 << 5,
@@ -134,6 +134,7 @@ enum {
 	FTRACE_OPS_FL_ALLOC_TRAMP		= 1 << 12,
 	FTRACE_OPS_FL_IPMODIFY			= 1 << 13,
 	FTRACE_OPS_FL_PID			= 1 << 14,
+	FTRACE_OPS_FL_RCU			= 1 << 15,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -146,11 +147,11 @@ struct ftrace_ops_hash {
 #endif
 
 /*
- * Note, ftrace_ops can be referenced outside of RCU protection.
- * (Although, for perf, the control ops prevent that). If ftrace_ops is
- * allocated and not part of kernel core data, the unregistering of it will
- * perform a scheduling on all CPUs to make sure that there are no more users.
- * Depending on the load of the system that may take a bit of time.
+ * Note, ftrace_ops can be referenced outside of RCU protection, unless
+ * the RCU flag is set. If ftrace_ops is allocated and not part of kernel
+ * core data, the unregistering of it will perform a scheduling on all CPUs
+ * to make sure that there are no more users. Depending on the load of the
+ * system that may take a bit of time.
  *
  * Any private data added must also take care not to be freed and if private
  * data is added to a ftrace_ops that is in core code, the user of the
@@ -196,34 +197,34 @@ int unregister_ftrace_function(struct ftrace_ops *ops);
 void clear_ftrace_function(void);
 
 /**
- * ftrace_function_local_enable - enable controlled ftrace_ops on current cpu
+ * ftrace_function_local_enable - enable ftrace_ops on current cpu
  *
  * This function enables tracing on current cpu by decreasing
  * the per cpu control variable.
  * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
+ * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
  */
 static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
 {
-	if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
+	if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
 		return;
 
 	(*this_cpu_ptr(ops->disabled))--;
 }
 
 /**
- * ftrace_function_local_disable - enable controlled ftrace_ops on current cpu
+ * ftrace_function_local_disable - disable ftrace_ops on current cpu
  *
- * This function enables tracing on current cpu by decreasing
+ * This function disables tracing on current cpu by increasing
  * the per cpu control variable.
  * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
+ * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
  */
 static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
 {
-	if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
+	if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
 		return;
 
 	(*this_cpu_ptr(ops->disabled))++;
@@ -235,12 +236,12 @@ static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
  *
  * This function returns value of ftrace_ops::disabled on current cpu.
  * It must be called with preemption disabled and only on ftrace_ops
- * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
+ * registered with FTRACE_OPS_FL_PER_CPU. If called without preemption
  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
  */
 static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 {
-	WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL));
+	WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU));
 	return *this_cpu_ptr(ops->disabled);
 }