Commit 6fb44b71 authored by Steven Rostedt's avatar Steven Rostedt Committed by Thomas Gleixner
Browse files

ftrace: add trace_function api for other tracers to use 



A new check was added in the ftrace function that wont trace if the CPU
trace buffer is disabled.  Unfortunately, other tracers used ftrace() to
write to the buffer after they disabled it. The new disable check makes
these calls into a nop.

This patch changes the __ftrace that is called without the check into a
new api for the other tracers to use, called "trace_function". The other
tracers use this interface instead when the trace CPU buffer is already
disabled.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2a2cc8f7

kernel/trace/trace.c

+4 −4
Original line number Diff line number Diff line
@@ -641,7 +641,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags) 
}



notrace void

__ftrace(struct trace_array *tr, struct trace_array_cpu *data,

trace_function(struct trace_array *tr, struct trace_array_cpu *data,

	       unsigned long ip, unsigned long parent_ip, unsigned long flags)

{

	struct trace_entry *entry;
@@ -664,7 +664,7 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data, 
       unsigned long ip, unsigned long parent_ip, unsigned long flags)

{

	if (likely(!atomic_read(&data->disabled)))

		__ftrace(tr, data, ip, parent_ip, flags);

		trace_function(tr, data, ip, parent_ip, flags);

}



notrace void
@@ -730,7 +730,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip) 
	disabled = atomic_inc_return(&data->disabled);



	if (likely(disabled == 1))

		__ftrace(tr, data, ip, parent_ip, flags);

		trace_function(tr, data, ip, parent_ip, flags);



	atomic_dec(&data->disabled);

	local_irq_restore(flags);

kernel/trace/trace.h

+5 −0
Original line number Diff line number Diff line
@@ -169,6 +169,11 @@ void trace_special(struct trace_array *tr, 
		   unsigned long arg1,

		   unsigned long arg2,

		   unsigned long arg3);

void trace_function(struct trace_array *tr,

		    struct trace_array_cpu *data,

		    unsigned long ip,

		    unsigned long parent_ip,

		    unsigned long flags);



void tracing_start_function_trace(void);

void tracing_stop_function_trace(void);

kernel/trace/trace_irqsoff.c

+5 −5
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip) 
	disabled = atomic_inc_return(&data->disabled);



	if (likely(disabled == 1))

		ftrace(tr, data, ip, parent_ip, flags);

		trace_function(tr, data, ip, parent_ip, flags);



	atomic_dec(&data->disabled);

}
@@ -150,7 +150,7 @@ check_critical_timing(struct trace_array *tr, 
	if (!report_latency(delta))

		goto out_unlock;



	ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);

	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags);



	latency = nsecs_to_usecs(delta);
@@ -188,7 +188,7 @@ out: 
	data->critical_sequence = max_sequence;

	data->preempt_timestamp = ftrace_now(cpu);

	tracing_reset(data);

	ftrace(tr, data, CALLER_ADDR0, parent_ip, flags);

	trace_function(tr, data, CALLER_ADDR0, parent_ip, flags);

}



static inline void notrace
@@ -221,7 +221,7 @@ start_critical_timing(unsigned long ip, unsigned long parent_ip) 


	local_save_flags(flags);



	ftrace(tr, data, ip, parent_ip, flags);

	trace_function(tr, data, ip, parent_ip, flags);



	__get_cpu_var(tracing_cpu) = 1;
@@ -254,7 +254,7 @@ stop_critical_timing(unsigned long ip, unsigned long parent_ip) 


	atomic_inc(&data->disabled);

	local_save_flags(flags);

	ftrace(tr, data, ip, parent_ip, flags);

	trace_function(tr, data, ip, parent_ip, flags);

	check_critical_timing(tr, data, parent_ip ? : ip, cpu);

	data->critical_start = 0;

	atomic_dec(&data->disabled);

kernel/trace/trace_sched_wakeup.c

+3 −2
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ wakeup_sched_switch(struct task_struct *prev, struct task_struct *next) 
	if (unlikely(!tracer_enabled || next != wakeup_task))

		goto out_unlock;



	ftrace(tr, data, CALLER_ADDR1, CALLER_ADDR2, flags);

	trace_function(tr, data, CALLER_ADDR1, CALLER_ADDR2, flags);



	/*

	 * usecs conversion is slow so we try to delay the conversion
@@ -192,7 +192,8 @@ wakeup_check_start(struct trace_array *tr, struct task_struct *p, 
	local_save_flags(flags);



	tr->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu);

	ftrace(tr, tr->data[wakeup_cpu], CALLER_ADDR1, CALLER_ADDR2, flags);

	trace_function(tr, tr->data[wakeup_cpu],

		       CALLER_ADDR1, CALLER_ADDR2, flags);



out_locked:

	spin_unlock(&wakeup_lock);

CRA Git | Maintained and supported by SUSTech CRA and CCSE