On Tue, 9 May 2023 12:29:23 +0000 Ajay Kaher akaher@vmware.com wrote:
> On 02/05/23, 11:42 PM, "kernel test robot" lkp@intel.com wrote:
kernel/trace/trace_events.c:2424:17: warning: variable 'd_events' set but not used [-Wunused-but-set-variable]
struct dentry *d_events; ^1 warning generated.
Steve, with-in event_create_dir(), do we have any scenario when file->event_call->class->system doesn't have TRACE_SYSTEM? And need to execute following:
ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent;
looking for your input if we could remove d_events from event_create_dir().
I have hit this in the beginning, but I don't think it's an issue anymore. Perhaps just have it be:
if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) return -ENODEV;
ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent);
Hmm, how about just add this patch before your patch set:
-- Steve
From: "Steven Rostedt (Google)" rostedt@goodmis.org Subject: [PATCH] tracing: Require all trace events to have a TRACE_SYSTEM
The creation of the trace event directory requires that a TRACE_SYSTEM is defined that the trace event directory is added within the system it was defined in.
The code handled the case where a TRACE_SYSTEM was not added, and would then add the event at the events directory. But nothing should be doing this. This code also prevents the implementation of creating dynamic dentrys for the eventfs system.
As this path has never been hit on correct code, remove it. If it does get hit, issues a WARN_ON_ONCE() and return ENODEV.
Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org ---
(lightly tested)
kernel/trace/trace_events.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 654ffa40457a..16bc5ba45507 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2424,14 +2424,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)
/* * If the trace point header did not define TRACE_SYSTEM - * then the system would be called "TRACE_SYSTEM". + * then the system would be called "TRACE_SYSTEM". This should + * never happen. */ - if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { - d_events = event_subsystem_dir(tr, call->class->system, file, parent); - if (!d_events) - return -ENOMEM; - } else - d_events = parent; + if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) + return -ENODEV; + + d_events = event_subsystem_dir(tr, call->class->system, file, parent); + if (!d_events) + return -ENOMEM;
name = trace_event_name(call); file->dir = tracefs_create_dir(name, d_events);