From f21ecbb35f865a508073c0e73854da469a07f278 Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Thu, 24 Oct 2013 08:59:27 -0500 Subject: [PATCH] tracing: Add 'stacktrace' event trigger command Add 'stacktrace' event_command. stacktrace event triggers are added by the user via this command in a similar way and using practically the same syntax as the analogous 'stacktrace' ftrace function command, but instead of writing to the set_ftrace_filter file, the stacktrace event trigger is written to the per-event 'trigger' files: echo 'stacktrace' > .../tracing/events/somesys/someevent/trigger The above command will turn on stacktraces for someevent i.e. whenever someevent is hit, a stacktrace will be logged. This also adds a 'count' version that limits the number of times the command will be invoked: echo 'stacktrace:N' > .../tracing/events/somesys/someevent/trigger Where N is the number of times the command will be invoked. The above command will log N stacktraces for someevent i.e. whenever someevent is hit N times, a stacktrace will be logged. Link: http://lkml.kernel.org/r/0c30c008a0828c660aa0e1bbd3255cf179ed5c30.1382622043.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt --- include/linux/ftrace_event.h | 1 + kernel/trace/trace_events_trigger.c | 79 +++++++++++++++++++++++++++++++++++++ 2 files changed, 80 insertions(+) diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 6efa8c2..65caee4 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -347,6 +347,7 @@ enum event_trigger_type { ETT_NONE = (0), ETT_TRACE_ONOFF = (1 << 0), ETT_SNAPSHOT = (1 << 1), + ETT_STACKTRACE = (1 << 2), }; extern void destroy_preds(struct ftrace_event_file *file); diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index d775c3d..a3bd1da 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -780,6 +780,84 @@ static __init int register_trigger_snapshot_cmd(void) static __init int register_trigger_snapshot_cmd(void) { return 0; } #endif /* CONFIG_TRACER_SNAPSHOT */ +#ifdef CONFIG_STACKTRACE +/* + * Skip 3: + * stacktrace_trigger() + * event_triggers_post_call() + * ftrace_raw_event_xxx() + */ +#define STACK_SKIP 3 + +static void +stacktrace_trigger(struct event_trigger_data *data) +{ + trace_dump_stack(STACK_SKIP); +} + +static void +stacktrace_count_trigger(struct event_trigger_data *data) +{ + if (!data->count) + return; + + if (data->count != -1) + (data->count)--; + + stacktrace_trigger(data); +} + +static int +stacktrace_trigger_print(struct seq_file *m, struct event_trigger_ops *ops, + struct event_trigger_data *data) +{ + return event_trigger_print("stacktrace", m, (void *)data->count, + data->filter_str); +} + +static struct event_trigger_ops stacktrace_trigger_ops = { + .func = stacktrace_trigger, + .print = stacktrace_trigger_print, + .init = event_trigger_init, + .free = event_trigger_free, +}; + +static struct event_trigger_ops stacktrace_count_trigger_ops = { + .func = stacktrace_count_trigger, + .print = stacktrace_trigger_print, + .init = event_trigger_init, + .free = event_trigger_free, +}; + +static struct event_trigger_ops * +stacktrace_get_trigger_ops(char *cmd, char *param) +{ + return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops; +} + +static struct event_command trigger_stacktrace_cmd = { + .name = "stacktrace", + .trigger_type = ETT_STACKTRACE, + .post_trigger = true, + .func = event_trigger_callback, + .reg = register_trigger, + .unreg = unregister_trigger, + .get_trigger_ops = stacktrace_get_trigger_ops, +}; + +static __init int register_trigger_stacktrace_cmd(void) +{ + int ret; + + ret = register_event_command(&trigger_stacktrace_cmd); + WARN_ON(ret < 0); + + return ret; +} +#else +static __init int register_trigger_stacktrace_cmd(void) { return 0; } +#endif /* CONFIG_STACKTRACE */ + static __init void unregister_trigger_traceon_traceoff_cmds(void) { unregister_event_command(&trigger_traceon_cmd); @@ -804,6 +882,7 @@ __init int register_trigger_cmds(void) { register_trigger_traceon_traceoff_cmds(); register_trigger_snapshot_cmd(); + register_trigger_stacktrace_cmd(); return 0; } -- 2.7.4