Commit 762e1207 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

tracing: Have stack tracing set filtered functions at boot 



Add stacktrace_filter= to the kernel command line that lets
the user pick specific functions to check the stack on.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 2a85a37f

Documentation/kernel-parameters.txt

+8 −0
Original line number Diff line number Diff line
@@ -2435,6 +2435,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
	stacktrace	[FTRACE]

			Enabled the stack tracer on boot up.



	stacktrace_filter=[function-list]

			[FTRACE] Limit the functions that the stack tracer

			will trace at boot up. function-list is a comma separated

			list of functions. This list can be changed at run

			time by the stack_trace_filter file in the debugfs

			tracing directory. Note, this enables stack tracing

			and the stacktrace above is not needed.



	sti=		[PARISC,HW]

			Format: <num>

			Set the STI (builtin display/keyboard on the HP-PARISC

kernel/trace/trace_stack.c

+11 −0
Original line number Diff line number Diff line
@@ -13,6 +13,9 @@ 
#include <linux/sysctl.h>

#include <linux/init.h>

#include <linux/fs.h>



#include <asm/setup.h>



#include "trace.h"



#define STACK_TRACE_ENTRIES 500
@@ -352,8 +355,13 @@ stack_trace_sysctl(struct ctl_table *table, int write, 
	return ret;

}



static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;



static __init int enable_stacktrace(char *str)

{

	if (strncmp(str, "_filter=", 8) == 0)

		strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);



	stack_tracer_enabled = 1;

	last_stack_tracer_enabled = 1;

	return 1;
@@ -375,6 +383,9 @@ static __init int stack_trace_init(void) 
	trace_create_file("stack_trace_filter", 0444, d_tracer,

			NULL, &stack_trace_filter_fops);



	if (stack_trace_filter_buf[0])

		ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);



	if (stack_tracer_enabled)

		register_ftrace_function(&trace_ops);