Commit 9cd2992f authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

fgraph: Have set_graph_notrace only affect function_graph tracer 



In order to make the function graph infrastructure more generic, there can
not be code specific for the function_graph tracer in the generic code. This
includes the set_graph_notrace logic, that stops all graph calls when a
function in the set_graph_notrace is hit.

By using the trace_recursion mask, we can use a bit in the current
task_struct to implement the notrace code, and move the logic out of
fgraph.c and into trace_functions_graph.c and keeps it affecting only the
tracer and not all call graph callbacks.

Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Reviewed-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent d864a3ca

kernel/trace/fgraph.c

+0 −21
Original line number Original line Diff line number Diff line
@@ -64,30 +64,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, 
		return -EBUSY;

		return -EBUSY;

	}

	}





	/*

	 * The curr_ret_stack is an index to ftrace return stack of

	 * current task.  Its value should be in [0, FTRACE_RETFUNC_

	 * DEPTH) when the function graph tracer is used.  To support

	 * filtering out specific functions, it makes the index

	 * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)

	 * so when it sees a negative index the ftrace will ignore

	 * the record.  And the index gets recovered when returning

	 * from the filtered function by adding the FTRACE_NOTRACE_

	 * DEPTH and then it'll continue to record functions normally.

	 *

	 * The curr_ret_stack is initialized to -1 and get increased

	 * in this function.  So it can be less than -1 only if it was

	 * filtered out via ftrace_graph_notrace_addr() which can be

	 * set from set_graph_notrace file in tracefs by user.

	 */

	if (current->curr_ret_stack < -1)

		return -EBUSY;



	calltime = trace_clock_local();

	calltime = trace_clock_local();





	index = ++current->curr_ret_stack;

	index = ++current->curr_ret_stack;

	if (ftrace_graph_notrace_addr(func))

		current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;

	barrier();

	barrier();

	current->ret_stack[index].ret = ret;

	current->ret_stack[index].ret = ret;

	current->ret_stack[index].func = func;

	current->ret_stack[index].func = func;

kernel/trace/trace.h

+7 −0
Original line number Original line Diff line number Diff line
@@ -534,6 +534,13 @@ enum { 




	TRACE_GRAPH_DEPTH_START_BIT,

	TRACE_GRAPH_DEPTH_START_BIT,

	TRACE_GRAPH_DEPTH_END_BIT,

	TRACE_GRAPH_DEPTH_END_BIT,



	/*

	 * To implement set_graph_notrace, if this bit is set, we ignore

	 * function graph tracing of called functions, until the return

	 * function is called to clear it.

	 */

	TRACE_GRAPH_NOTRACE_BIT,

};

};





#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (1<<(bit)); } while (0)

#define trace_recursion_set(bit)	do { (current)->trace_recursion |= (1<<(bit)); } while (0)

kernel/trace/trace_functions_graph.c

+22 −0
Original line number Original line Diff line number Diff line
@@ -188,6 +188,18 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) 
	int cpu;

	int cpu;

	int pc;

	int pc;





	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))

		return 0;



	if (ftrace_graph_notrace_addr(trace->func)) {

		trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);

		/*

		 * Need to return 1 to have the return called

		 * that will clear the NOTRACE bit.

		 */

		return 1;

	}



	if (!ftrace_trace_task(tr))

	if (!ftrace_trace_task(tr))

		return 0;

		return 0;
@@ -290,6 +302,11 @@ void trace_graph_return(struct ftrace_graph_ret *trace) 




	ftrace_graph_addr_finish(trace);

	ftrace_graph_addr_finish(trace);





	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {

		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);

		return;

	}



	local_irq_save(flags);

	local_irq_save(flags);

	cpu = raw_smp_processor_id();

	cpu = raw_smp_processor_id();

	data = per_cpu_ptr(tr->trace_buffer.data, cpu);

	data = per_cpu_ptr(tr->trace_buffer.data, cpu);
@@ -315,6 +332,11 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace) 
{

{

	ftrace_graph_addr_finish(trace);

	ftrace_graph_addr_finish(trace);





	if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {

		trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);

		return;

	}



	if (tracing_thresh &&

	if (tracing_thresh &&

	    (trace->rettime - trace->calltime < tracing_thresh))

	    (trace->rettime - trace->calltime < tracing_thresh))

		return;

		return;

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