From: Masami Hiramatsu mhiramat@kernel.org

Fix to allow user to enable probe events on unloaded modules.

This operations was allowed before commit 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe"), because if users need to probe module init functions, they have to enable those probe events before loading module.

Link: http://lkml.kernel.org/r/156879693733.31056.9331322616994665167.stgit@devnot...

Cc: stable@vger.kernel.org Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org --- kernel/trace/trace_kprobe.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 7579c53bb053..0ba3239c0270 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -371,31 +371,24 @@ static int enable_trace_kprobe(struct trace_event_call *call, if (enabled) return 0;

- enabled = false; list_for_each_entry(pos, trace_probe_probe_list(tp), list) { tk = container_of(pos, struct trace_kprobe, tp); if (trace_kprobe_has_gone(tk)) continue; ret = __enable_trace_kprobe(tk); - if (ret) { - if (enabled) { - __disable_trace_kprobe(tp); - enabled = false; - } + if (ret) break; - } enabled = true; }

- if (!enabled) { - /* No probe is enabled. Roll back */ + if (ret) { + /* Failed to enable one of them. Roll back all */ + if (enabled) + __disable_trace_kprobe(tp); if (file) trace_probe_remove_file(tp, file); else trace_probe_clear_flag(tp, TP_FLAG_PROFILE); - if (!ret) - /* Since all probes are gone, this is not available */ - ret = -EADDRNOTAVAIL; }

return ret;