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Date: Fri, 15 Mar 2013 15:39:48 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Frederic Weisbecker <fweisbec@...il.com>
Subject: [for-next][PATCH 13/20] tracing: Add function probe to trigger stack traces
From: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
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@...dmis.org>
---
kernel/trace/trace_functions.c | 150 ++++++++++++++++++++++++++++++----------
1 file changed, 115 insertions(+), 35 deletions(-)
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 043b242..c4d6d71 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -265,56 +265,103 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
tracing_off();
}
+/*
+ * Skip 4:
+ * ftrace_stacktrace()
+ * function_trace_probe_call()
+ * ftrace_ops_list_func()
+ * ftrace_call()
+ */
+#define STACK_SKIP 4
+
+static void
+ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ trace_dump_stack(STACK_SKIP);
+}
+
+static void
+ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
+{
+ if (!tracing_is_on())
+ return;
+
+ 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:%s", (void *)ip, name);
+
+ if (count == -1)
+ seq_printf(m, ":unlimited\n");
+ else
+ seq_printf(m, ":count=%ld\n", count);
+
+ return 0;
+}
+
+static int
+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_trace_onoff_print,
+ .print = ftrace_traceon_print,
};
static struct ftrace_probe_ops traceoff_count_probe_ops = {
.func = ftrace_traceoff_count,
- .print = ftrace_trace_onoff_print,
+ .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_trace_onoff_print,
+ .print = ftrace_traceon_print,
};
static struct ftrace_probe_ops traceoff_probe_ops = {
.func = ftrace_traceoff,
- .print = ftrace_trace_onoff_print,
+ .print = ftrace_traceoff_print,
};
-static int
-ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
- struct ftrace_probe_ops *ops, 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");
-
- if (count == -1)
- seq_printf(m, ":unlimited\n");
- else
- seq_printf(m, ":count=%ld\n", count);
-
- return 0;
-}
+static struct ftrace_probe_ops stacktrace_probe_ops = {
+ .func = ftrace_stacktrace,
+ .print = ftrace_stacktrace_print,
+};
static int
-ftrace_trace_onoff_callback(struct ftrace_hash *hash,
- char *glob, char *cmd, char *param, int enable)
+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
--
1.7.10.4
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