[linux-2.6-block.git] / kernel / trace / trace_nop.c

/*
 * nop tracer
 *
 * Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net>
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>

#include "trace.h"

/* Our two options */
enum {
	TRACE_NOP_OPT_ACCEPT = 0x1,
	TRACE_NOP_OPT_REFUSE = 0x2
};

/* Options for the tracer (see trace_options file) */
static struct tracer_opt nop_opts[] = {
	/* Option that will be accepted by set_flag callback */
	{ TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
	/* Option that will be refused by set_flag callback */
	{ TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
	{ } /* Always set a last empty entry */
};

static struct tracer_flags nop_flags = {
	/* You can check your flags value here when you want. */
	.val = 0, /* By default: all flags disabled */
	.opts = nop_opts
};

static struct trace_array	*ctx_trace;

static void start_nop_trace(struct trace_array *tr)
{
	/* Nothing to do! */
}

static void stop_nop_trace(struct trace_array *tr)
{
	/* Nothing to do! */
}

static int nop_trace_init(struct trace_array *tr)
{
	int cpu;
	ctx_trace = tr;

	for_each_online_cpu(cpu)
		tracing_reset(tr, cpu);

	start_nop_trace(tr);
	return 0;
}

static void nop_trace_reset(struct trace_array *tr)
{
	stop_nop_trace(tr);
}

/* It only serves as a signal handler and a callback to
 * accept or refuse tthe setting of a flag.
 * If you don't implement it, then the flag setting will be
 * automatically accepted.
 */
static int nop_set_flag(u32 old_flags, u32 bit, int set)
{
	/*
	 * Note that you don't need to update nop_flags.val yourself.
	 * The tracing Api will do it automatically if you return 0
	 */
	if (bit == TRACE_NOP_OPT_ACCEPT) {
		printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
			" Now cat trace_options to see the result\n",
			set);
		return 0;
	}

	if (bit == TRACE_NOP_OPT_REFUSE) {
		printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
			"Now cat trace_options to see the result\n",
			set);
		return -EINVAL;
	}

	return 0;
}


struct tracer nop_trace __read_mostly =
{
	.name		= "nop",
	.init		= nop_trace_init,
	.reset		= nop_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
	.selftest	= trace_selftest_startup_nop,
#endif
	.flags		= &nop_flags,
	.set_flag	= nop_set_flag
};
Commit	Line	Data
fb1b6d8b SN	1	/*
	2	* nop tracer
	3	*
	4	* Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net>
	5	*
	6	*/
	7
	8	#include <linux/module.h>
	9	#include <linux/fs.h>
	10	#include <linux/debugfs.h>
	11	#include <linux/ftrace.h>
	12
	13	#include "trace.h"
	14
0619faf6 FW	15	/* Our two options */
	16	enum {
	17	TRACE_NOP_OPT_ACCEPT = 0x1,
	18	TRACE_NOP_OPT_REFUSE = 0x2
	19	};
	20
	21	/* Options for the tracer (see trace_options file) */
	22	static struct tracer_opt nop_opts[] = {
	23	/* Option that will be accepted by set_flag callback */
	24	{ TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
	25	/* Option that will be refused by set_flag callback */
	26	{ TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
	27	{ } /* Always set a last empty entry */
	28	};
	29
	30	static struct tracer_flags nop_flags = {
	31	/* You can check your flags value here when you want. */
	32	.val = 0, /* By default: all flags disabled */
	33	.opts = nop_opts
	34	};
	35
fb1b6d8b SN	36	static struct trace_array *ctx_trace;
	37
	38	static void start_nop_trace(struct trace_array *tr)
	39	{
	40	/* Nothing to do! */
	41	}
	42
	43	static void stop_nop_trace(struct trace_array *tr)
	44	{
	45	/* Nothing to do! */
	46	}
	47
1c80025a	48	static int nop_trace_init(struct trace_array *tr)
fb1b6d8b	49	{
35cb5ed0	50	int cpu;
fb1b6d8b SN	51	ctx_trace = tr;
fb1b6d8b SN	52
35cb5ed0	53	for_each_online_cpu(cpu)
3928a8a2	54	tracing_reset(tr, cpu);
35cb5ed0	55
c76f0694	56	start_nop_trace(tr);
1c80025a	57	return 0;
fb1b6d8b SN	58	}
	59
	60	static void nop_trace_reset(struct trace_array *tr)
	61	{
c76f0694	62	stop_nop_trace(tr);
fb1b6d8b SN	63	}
fb1b6d8b SN	64
0619faf6 FW	65	/* It only serves as a signal handler and a callback to
	66	* accept or refuse tthe setting of a flag.
	67	* If you don't implement it, then the flag setting will be
	68	* automatically accepted.
	69	*/
	70	static int nop_set_flag(u32 old_flags, u32 bit, int set)
	71	{
	72	/*
	73	* Note that you don't need to update nop_flags.val yourself.
	74	* The tracing Api will do it automatically if you return 0
	75	*/
	76	if (bit == TRACE_NOP_OPT_ACCEPT) {
	77	printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
	78	" Now cat trace_options to see the result\n",
	79	set);
	80	return 0;
	81	}
	82
	83	if (bit == TRACE_NOP_OPT_REFUSE) {
	84	printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
	85	"Now cat trace_options to see the result\n",
	86	set);
	87	return -EINVAL;
	88	}
	89
	90	return 0;
	91	}
	92
	93
43a15386	94	struct tracer nop_trace __read_mostly =
fb1b6d8b SN	95	{
	96	.name = "nop",
	97	.init = nop_trace_init,
	98	.reset = nop_trace_reset,
fb1b6d8b SN	99	#ifdef CONFIG_FTRACE_SELFTEST
	100	.selftest = trace_selftest_startup_nop,
	101	#endif
0619faf6 FW	102	.flags = &nop_flags,
0619faf6 FW	103	.set_flag = nop_set_flag
fb1b6d8b SN	104	};
fb1b6d8b SN	105