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Commit 43a15386 authored by Frédéric Weisbecker's avatar Frédéric Weisbecker Committed by Ingo Molnar
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tracing/ftrace: replace none tracer by nop tracer 



Replace "none" tracer by the recently created "nop" tracer.
Both are pretty similar except that nop accepts TRACE_PRINT
or TRACE_SPECIAL entries.

And as a consequence, changing the size of the ring buffer now
requires that tracing has already been disabled.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2a3a4f66

kernel/trace/trace.c

+9 −40
Original line number Diff line number Diff line
@@ -142,24 +142,6 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait); 
/* trace_flags holds iter_ctrl options */

unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;



static notrace void no_trace_init(struct trace_array *tr)

{

	int cpu;



	ftrace_function_enabled = 0;

	if(tr->ctrl)

		for_each_online_cpu(cpu)

			tracing_reset(tr->data[cpu]);

	tracer_enabled = 0;

}



/* dummy trace to disable tracing */

static struct tracer no_tracer __read_mostly = {

	.name		= "none",

	.init		= no_trace_init

};





/**

 * trace_wake_up - wake up tasks waiting for trace input

 *
@@ -962,7 +944,7 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) 
	long disabled;

	int cpu;



	if (tracing_disabled || current_trace == &no_tracer || !tr->ctrl)

	if (tracing_disabled || !tr->ctrl)

		return;



	local_irq_save(flags);
@@ -2795,6 +2777,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf, 
	unsigned long val;

	char buf[64];

	int i, ret;

	struct trace_array *tr = filp->private_data;



	if (cnt >= sizeof(buf))

		return -EINVAL;
@@ -2814,9 +2797,9 @@ tracing_entries_write(struct file *filp, const char __user *ubuf, 


	mutex_lock(&trace_types_lock);



	if (current_trace != &no_tracer) {

	if (tr->ctrl) {

		cnt = -EBUSY;

		pr_info("ftrace: set current_tracer to none"

		pr_info("ftrace: please disable tracing"

			" before modifying buffer size\n");

		goto out;

	}
@@ -2879,20 +2862,6 @@ tracing_entries_write(struct file *filp, const char __user *ubuf, 
	return cnt;

}



static int tracing_open_mark(struct inode *inode, struct file *filp)

{

	int ret;



	ret = tracing_open_generic(inode, filp);

	if (ret)

		return ret;



	if (current_trace == &no_tracer)

		return -ENODEV;



	return 0;

}



static int mark_printk(const char *fmt, ...)

{

	int ret;
@@ -2911,7 +2880,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, 
	char *end;

	struct trace_array *tr = &global_trace;



	if (current_trace == &no_tracer || !tr->ctrl || tracing_disabled)

	if (!tr->ctrl || tracing_disabled)

		return -EINVAL;



	if (cnt > TRACE_BUF_SIZE)
@@ -2971,7 +2940,7 @@ static struct file_operations tracing_entries_fops = { 
};



static struct file_operations tracing_mark_fops = {

	.open		= tracing_open_mark,

	.open		= tracing_open_generic,

	.write		= tracing_mark_write,

};
@@ -3123,7 +3092,7 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args) 
	long disabled;

	int cpu, len = 0, write, written = 0;



	if (current_trace == &no_tracer || !tr->ctrl || tracing_disabled)

	if (!tr->ctrl || tracing_disabled)

		return 0;



	local_irq_save(flags);
@@ -3539,8 +3508,8 @@ __init static int tracer_alloc_buffers(void) 


	trace_init_cmdlines();



	register_tracer(&no_tracer);

	current_trace = &no_tracer;

	register_tracer(&nop_trace);

	current_trace = &nop_trace;



	/* All seems OK, enable tracing */

	global_trace.ctrl = tracer_enabled;

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -369,4 +369,6 @@ enum trace_iterator_flags { 
	TRACE_ITER_PRINTK		= 0x400,

};



extern struct tracer nop_trace;



#endif /* _LINUX_KERNEL_TRACE_H */

kernel/trace/trace_nop.c

+1 −6
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ static void nop_trace_ctrl_update(struct trace_array *tr) 
		stop_nop_trace(tr);

}



static struct tracer nop_trace __read_mostly =

struct tracer nop_trace __read_mostly =

{

	.name		= "nop",

	.init		= nop_trace_init,
@@ -62,8 +62,3 @@ static struct tracer nop_trace __read_mostly = 
#endif

};

__init static int init_nop_trace(void)

{

	return register_tracer(&nop_trace);

}

device_initcall(init_nop_trace);