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ftrace: ftrace_dump_on_oops=[tracer]

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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-11-01 19:57:37 +01:00 committed by Ingo Molnar
parent 36609469c8
commit d9e540762f
2 changed files with 46 additions and 20 deletions
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8
Documentation/kernel-parameters.txt
View file

@ -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)

58
kernel/trace/trace.c
View file

@ -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;