Commit 23b4ff3a authored by Steven Rostedt's avatar Steven Rostedt
Browse files

ftrace: add traceon traceoff commands to enable/disable the buffers 



This patch adds the new function selection commands traceon and
traceoff. traceon sets the function to enable the ring buffers
while traceoff disables the ring buffers.  You can pass in the
number of times you want the command to be executed when the function
is hit. It will only execute if the state of the buffers are not
already in that state.

Example:

 # echo do_fork:traceon:4

Will enable the ring buffers if they are disabled every time it
hits do_fork, up to 4 times.

 # echo sys_close:traceoff

This will disable the ring buffers every time (unlimited) when
sys_close is called.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent 988ae9d6

kernel/trace/trace_functions.c

+135 −0
Original line number Original line Diff line number Diff line
@@ -9,6 +9,7 @@ 
 *  Copyright (C) 2004-2006 Ingo Molnar

 *  Copyright (C) 2004-2006 Ingo Molnar

 *  Copyright (C) 2004 William Lee Irwin III

 *  Copyright (C) 2004 William Lee Irwin III

 */

 */

#include <linux/ring_buffer.h>

#include <linux/debugfs.h>

#include <linux/debugfs.h>

#include <linux/uaccess.h>

#include <linux/uaccess.h>

#include <linux/ftrace.h>

#include <linux/ftrace.h>
@@ -231,9 +232,143 @@ static struct tracer function_trace __read_mostly = 
#endif

#endif

};

};





#ifdef CONFIG_DYNAMIC_FTRACE

static void

ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)

{

	long *count = (long *)data;



	if (tracing_is_on())

		return;



	if (!*count)

		return;



	if (*count != -1)

		(*count)--;



	tracing_on();

}



static void

ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)

{

	long *count = (long *)data;



	if (!tracing_is_on())

		return;



	if (!*count)

		return;



	if (*count != -1)

		(*count)--;



	tracing_off();

}



static struct ftrace_hook_ops traceon_hook_ops = {

	.func			= ftrace_traceon,

};



static struct ftrace_hook_ops traceoff_hook_ops = {

	.func			= ftrace_traceoff,

};



static int

ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)

{

	struct ftrace_hook_ops *ops;



	/* we register both traceon and traceoff to this callback */

	if (strcmp(cmd, "traceon") == 0)

		ops = &traceon_hook_ops;

	else

		ops = &traceoff_hook_ops;



	unregister_ftrace_function_hook_func(glob, ops);



	return 0;

}



static int

ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)

{

	struct ftrace_hook_ops *ops;

	void *count = (void *)-1;

	char *number;

	int ret;



	/* hash funcs only work with set_ftrace_filter */

	if (!enable)

		return -EINVAL;



	if (glob[0] == '!')

		return ftrace_trace_onoff_unreg(glob+1, cmd, param);



	/* we register both traceon and traceoff to this callback */

	if (strcmp(cmd, "traceon") == 0)

		ops = &traceon_hook_ops;

	else

		ops = &traceoff_hook_ops;



	if (!param)

		goto out_reg;



	number = strsep(&param, ":");



	if (!strlen(number))

		goto out_reg;



	/*

	 * We use the callback data field (which is a pointer)

	 * as our counter.

	 */

	ret = strict_strtoul(number, 0, (unsigned long *)&count);

	if (ret)

		return ret;



 out_reg:

	ret = register_ftrace_function_hook(glob, ops, count);



	return ret;

}



static struct ftrace_func_command ftrace_traceon_cmd = {

	.name			= "traceon",

	.func			= ftrace_trace_onoff_callback,

};



static struct ftrace_func_command ftrace_traceoff_cmd = {

	.name			= "traceoff",

	.func			= ftrace_trace_onoff_callback,

};



static int __init init_func_cmd_traceon(void)

{

	int ret;



	ret = register_ftrace_command(&ftrace_traceoff_cmd);

	if (ret)

		return ret;



	ret = register_ftrace_command(&ftrace_traceon_cmd);

	if (ret)

		unregister_ftrace_command(&ftrace_traceoff_cmd);

	return ret;

}

#else

static inline int init_func_cmd_traceon(void)

{

	return 0;

}

#endif /* CONFIG_DYNAMIC_FTRACE */



static __init int init_function_trace(void)

static __init int init_function_trace(void)

{

{

	init_func_cmd_traceon();

	return register_tracer(&function_trace);

	return register_tracer(&function_trace);

}

}





device_initcall(init_function_trace);

device_initcall(init_function_trace);

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