Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d9e54076 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

ftrace: ftrace_dump_on_oops=[tracer] 



Impact: add new (optional) debug boot option

In order to facilitate early boot trouble, allow one to specify a tracer
on the kernel boot line.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 36609469

Documentation/kernel-parameters.txt

+8 −0
Original line number Diff line number Diff line
@@ -765,6 +765,14 @@ and is between 256 and 4096 characters. It is defined in the file 
			parameter will force ia64_sal_cache_flush to call

			ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.



	ftrace=[tracer]

			[ftrace] will set and start the specified tracer

			as early as possible in order to facilitate early

			boot debugging.



	ftrace_dump_on_oops

			[ftrace] will dump the trace buffers on oops.



	gamecon.map[2|3]=

			[HW,JOY] Multisystem joystick and NES/SNES/PSX pad

			support via parallel port (up to 5 devices per port)

kernel/trace/trace.c

+38 −20
Original line number Diff line number Diff line
@@ -79,6 +79,15 @@ static int tracing_disabled = 1; 
 */

int ftrace_dump_on_oops;



static int tracing_set_tracer(char *buf);



static int __init set_ftrace(char *str)

{

	tracing_set_tracer(str);

	return 1;

}

__setup("ftrace", set_ftrace);



static int __init set_ftrace_dump_on_oops(char *str)

{

	ftrace_dump_on_oops = 1;
@@ -2394,29 +2403,11 @@ tracing_set_trace_read(struct file *filp, char __user *ubuf, 
	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

}



static ssize_t

tracing_set_trace_write(struct file *filp, const char __user *ubuf,

			size_t cnt, loff_t *ppos)

static int tracing_set_tracer(char *buf)

{

	struct trace_array *tr = &global_trace;

	struct tracer *t;

	char buf[max_tracer_type_len+1];

	int i;

	size_t ret;



	ret = cnt;



	if (cnt > max_tracer_type_len)

		cnt = max_tracer_type_len;



	if (copy_from_user(&buf, ubuf, cnt))

		return -EFAULT;



	buf[cnt] = 0;



	/* strip ending whitespace. */

	for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)

		buf[i] = 0;

	int ret = 0;



	mutex_lock(&trace_types_lock);

	for (t = trace_types; t; t = t->next) {
@@ -2440,6 +2431,33 @@ tracing_set_trace_write(struct file *filp, const char __user *ubuf, 
 out:

	mutex_unlock(&trace_types_lock);



	return ret;

}



static ssize_t

tracing_set_trace_write(struct file *filp, const char __user *ubuf,

			size_t cnt, loff_t *ppos)

{

	char buf[max_tracer_type_len+1];

	int i;

	size_t ret;



	if (cnt > max_tracer_type_len)

		cnt = max_tracer_type_len;



	if (copy_from_user(&buf, ubuf, cnt))

		return -EFAULT;



	buf[cnt] = 0;



	/* strip ending whitespace. */

	for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)

		buf[i] = 0;



	ret = tracing_set_tracer(buf);

	if (!ret)

		ret = cnt;



	if (ret > 0)

		filp->f_pos += ret;