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tracing: Add function probe to trigger stack traces 

Add a function probe that will cause a stack trace to be traced in
the ring buffer when the given function(s) are called.

format is:

 <function>:stacktrace[:<count>]

 echo 'schedule:stacktrace' > /debug/tracing/set_ftrace_filter
 cat /debug/tracing/trace_pipe
     kworker/2:0-4329  [002] ...2  2933.558007: <stack trace>
 => kthread
 => ret_from_fork
          <idle>-0     [000] .N.2  2933.558019: <stack trace>
 => rest_init
 => start_kernel
 => x86_64_start_reservations
 => x86_64_start_kernel
     kworker/2:0-4329  [002] ...2  2933.558109: <stack trace>
 => kthread
 => ret_from_fork
[...]

This can be set to only trace a specific amount of times:

 echo 'schedule:stacktrace:3' > /debug/tracing/set_ftrace_filter
 cat /debug/tracing/trace_pipe
           <...>-58    [003] ...2   841.801694: <stack trace>
 => kthread
 => ret_from_fork
          <idle>-0     [001] .N.2   841.801697: <stack trace>
 => start_secondary
           <...>-2059  [001] ...2   841.801736: <stack trace>
 => wait_for_common
 => wait_for_completion
 => flush_work
 => tty_flush_to_ldisc
 => input_available_p
 => n_tty_poll
 => tty_poll
 => do_select
 => core_sys_select
 => sys_select
 => system_call_fastpath

To remove these:

 echo '!schedule:stacktrace' > /debug/tracing/set_ftrace_filter
 echo '!schedule:stacktrace:0' > /debug/tracing/set_ftrace_filter

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-13 10:17:50 -04:00 committed by Steven Rostedt
parent c142be8ebe
commit dd42cd3ea9
1 changed files with 117 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

154
kernel/trace/trace_functions.c
View File

@ -265,42 +265,38 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
tracing_off();
}
static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data);
/*
* Skip 4:
* ftrace_stacktrace()
* function_trace_probe_call()
* ftrace_ops_list_func()
* ftrace_call()
*/
#define STACK_SKIP 4
static struct ftrace_probe_ops traceon_count_probe_ops = {
.func = ftrace_traceon_count,
.print = ftrace_trace_onoff_print,
};
static void
ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
{
trace_dump_stack(STACK_SKIP);
}
static struct ftrace_probe_ops traceoff_count_probe_ops = {
.func = ftrace_traceoff_count,
.print = ftrace_trace_onoff_print,
};
static void
ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
{
if (!tracing_is_on())
return;
static struct ftrace_probe_ops traceon_probe_ops = {
.func = ftrace_traceon,
.print = ftrace_trace_onoff_print,
};
static struct ftrace_probe_ops traceoff_probe_ops = {
.func = ftrace_traceoff,
.print = ftrace_trace_onoff_print,
};
if (update_count(data))
trace_dump_stack(STACK_SKIP);
}
static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
ftrace_probe_print(const char *name, struct seq_file *m,
unsigned long ip, void *data)
{
long count = (long)data;
seq_printf(m, "%ps:", (void *)ip);
if (ops == &traceon_probe_ops || ops == &traceon_count_probe_ops)
seq_printf(m, "traceon");
else
seq_printf(m, "traceoff");
seq_printf(m, "%ps:%s", (void *)ip, name);
if (count == -1)
seq_printf(m, ":unlimited\n");
@ -311,10 +307,61 @@ ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
}
static int
ftrace_trace_onoff_callback(struct ftrace_hash *hash,
char *glob, char *cmd, char *param, int enable)
ftrace_traceon_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
{
return ftrace_probe_print("traceon", m, ip, data);
}
static int
ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
{
return ftrace_probe_print("traceoff", m, ip, data);
}
static int
ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
{
return ftrace_probe_print("stacktrace", m, ip, data);
}
static struct ftrace_probe_ops traceon_count_probe_ops = {
.func = ftrace_traceon_count,
.print = ftrace_traceon_print,
};
static struct ftrace_probe_ops traceoff_count_probe_ops = {
.func = ftrace_traceoff_count,
.print = ftrace_traceoff_print,
};
static struct ftrace_probe_ops stacktrace_count_probe_ops = {
.func = ftrace_stacktrace_count,
.print = ftrace_stacktrace_print,
};
static struct ftrace_probe_ops traceon_probe_ops = {
.func = ftrace_traceon,
.print = ftrace_traceon_print,
};
static struct ftrace_probe_ops traceoff_probe_ops = {
.func = ftrace_traceoff,
.print = ftrace_traceoff_print,
};
static struct ftrace_probe_ops stacktrace_probe_ops = {
.func = ftrace_stacktrace,
.print = ftrace_stacktrace_print,
};
static int
ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
struct ftrace_hash *hash, char *glob,
char *cmd, char *param, int enable)
{
struct ftrace_probe_ops *ops;
void *count = (void *)-1;
char *number;
int ret;
@ -323,12 +370,6 @@ ftrace_trace_onoff_callback(struct ftrace_hash *hash,
if (!enable)
return -EINVAL;
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
else
ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
if (glob[0] == '!') {
unregister_ftrace_function_probe_func(glob+1, ops);
return 0;
@ -356,6 +397,34 @@ ftrace_trace_onoff_callback(struct ftrace_hash *hash,
return ret < 0 ? ret : 0;
}
static int
ftrace_trace_onoff_callback(struct ftrace_hash *hash,
char *glob, char *cmd, char *param, int enable)
{
struct ftrace_probe_ops *ops;
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
else
ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
return ftrace_trace_probe_callback(ops, hash, glob, cmd,
param, enable);
}
static int
ftrace_stacktrace_callback(struct ftrace_hash *hash,
char *glob, char *cmd, char *param, int enable)
{
struct ftrace_probe_ops *ops;
ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
return ftrace_trace_probe_callback(ops, hash, glob, cmd,
param, enable);
}
static struct ftrace_func_command ftrace_traceon_cmd = {
.name = "traceon",
.func = ftrace_trace_onoff_callback,
@ -366,6 +435,11 @@ static struct ftrace_func_command ftrace_traceoff_cmd = {
.func = ftrace_trace_onoff_callback,
};
static struct ftrace_func_command ftrace_stacktrace_cmd = {
.name = "stacktrace",
.func = ftrace_stacktrace_callback,
};
static int __init init_func_cmd_traceon(void)
{
int ret;
@ -377,6 +451,12 @@ static int __init init_func_cmd_traceon(void)
ret = register_ftrace_command(&ftrace_traceon_cmd);
if (ret)
unregister_ftrace_command(&ftrace_traceoff_cmd);
ret = register_ftrace_command(&ftrace_stacktrace_cmd);
if (ret) {
unregister_ftrace_command(&ftrace_traceoff_cmd);
unregister_ftrace_command(&ftrace_traceon_cmd);
}
return ret;
}
#else