4.19-stable review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
commit 0e2b81f7b52a1c1a8c46986f9ca01eb7b3c421f8 upstream.
Rmove unneeded synth_event_mutex. This mutex protects the reference count in synth_event, however, those operational points are already protected by event_mutex.
1. In __create_synth_event() and create_or_delete_synth_event(), those synth_event_mutex clearly obtained right after event_mutex.
2. event_hist_trigger_func() is trigger_hist_cmd.func() which is called by trigger_process_regex(), which is a part of event_trigger_regex_write() and this function takes event_mutex.
3. hist_unreg_all() is trigger_hist_cmd.unreg_all() which is called by event_trigger_regex_open() and it takes event_mutex.
4. onmatch_destroy() and onmatch_create() have long call tree, but both are finally invoked from event_trigger_regex_write() and event_trace_del_tracer(), former takes event_mutex, and latter ensures called under event_mutex locked.
Finally, I ensured there is no resource conflict. For safety, I added lockdep_assert_held(&event_mutex) for each function.
Link: http://lkml.kernel.org/r/154140864134.17322.4796059721306031894.stgit@devbox
Reviewed-by: Tom Zanussi tom.zanussi@linux.intel.com Tested-by: Tom Zanussi tom.zanussi@linux.intel.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: George Guo guodongtai@kylinos.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace_events_hist.c | 30 +++++++----------------------- 1 file changed, 7 insertions(+), 23 deletions(-)
--- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -443,8 +443,6 @@ static bool have_hist_err(void) return false; }
-static DEFINE_MUTEX(synth_event_mutex); - struct synth_trace_event { struct trace_entry ent; u64 fields[]; @@ -1097,7 +1095,6 @@ static int __create_synth_event(int argc return -EINVAL;
mutex_lock(&event_mutex); - mutex_lock(&synth_event_mutex);
event = find_synth_event(name); if (event) { @@ -1139,7 +1136,6 @@ static int __create_synth_event(int argc else free_synth_event(event); out: - mutex_unlock(&synth_event_mutex); mutex_unlock(&event_mutex);
return ret; @@ -1159,7 +1155,6 @@ static int create_or_delete_synth_event( /* trace_run_command() ensures argc != 0 */ if (name[0] == '!') { mutex_lock(&event_mutex); - mutex_lock(&synth_event_mutex); event = find_synth_event(name + 1); if (event) { if (event->ref) @@ -1173,7 +1168,6 @@ static int create_or_delete_synth_event( } } else ret = -ENOENT; - mutex_unlock(&synth_event_mutex); mutex_unlock(&event_mutex); return ret; } @@ -3660,7 +3654,7 @@ static void onmatch_destroy(struct actio { unsigned int i;
- mutex_lock(&synth_event_mutex); + lockdep_assert_held(&event_mutex);
kfree(data->onmatch.match_event); kfree(data->onmatch.match_event_system); @@ -3673,8 +3667,6 @@ static void onmatch_destroy(struct actio data->onmatch.synth_event->ref--;
kfree(data); - - mutex_unlock(&synth_event_mutex); }
static void destroy_field_var(struct field_var *field_var) @@ -3810,15 +3802,14 @@ static int onmatch_create(struct hist_tr struct synth_event *event; int ret = 0;
- mutex_lock(&synth_event_mutex); + lockdep_assert_held(&event_mutex); + event = find_synth_event(data->onmatch.synth_event_name); if (!event) { hist_err("onmatch: Couldn't find synthetic event: ", data->onmatch.synth_event_name); - mutex_unlock(&synth_event_mutex); return -EINVAL; } event->ref++; - mutex_unlock(&synth_event_mutex);
var_ref_idx = hist_data->n_var_refs;
@@ -3892,9 +3883,7 @@ static int onmatch_create(struct hist_tr out: return ret; err: - mutex_lock(&synth_event_mutex); event->ref--; - mutex_unlock(&synth_event_mutex);
goto out; } @@ -5611,6 +5600,8 @@ static void hist_unreg_all(struct trace_ struct synth_event *se; const char *se_name;
+ lockdep_assert_held(&event_mutex); + if (hist_file_check_refs(file)) return;
@@ -5620,12 +5611,10 @@ static void hist_unreg_all(struct trace_ list_del_rcu(&test->list); trace_event_trigger_enable_disable(file, 0);
- mutex_lock(&synth_event_mutex); se_name = trace_event_name(file->event_call); se = find_synth_event(se_name); if (se) se->ref--; - mutex_unlock(&synth_event_mutex);
update_cond_flag(file); if (hist_data->enable_timestamps) @@ -5651,6 +5640,8 @@ static int event_hist_trigger_func(struc char *trigger, *p; int ret = 0;
+ lockdep_assert_held(&event_mutex); + if (glob && strlen(glob)) { last_cmd_set(param); hist_err_clear(); @@ -5741,14 +5732,10 @@ static int event_hist_trigger_func(struc }
cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file); - - mutex_lock(&synth_event_mutex); se_name = trace_event_name(file->event_call); se = find_synth_event(se_name); if (se) se->ref--; - mutex_unlock(&synth_event_mutex); - ret = 0; goto out_free; } @@ -5787,13 +5774,10 @@ enable: if (ret) goto out_unreg;
- mutex_lock(&synth_event_mutex); se_name = trace_event_name(file->event_call); se = find_synth_event(se_name); if (se) se->ref++; - mutex_unlock(&synth_event_mutex); - /* Just return zero, not the number of registered triggers */ ret = 0; out: