Messages in this thread | | | Date | Thu, 19 Aug 2021 13:28:36 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v6 7/7] tracing: Add a probe that attaches to trace events |
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On Thu, 19 Aug 2021 00:03:42 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 19 Aug 2021 12:56:52 +0900 > Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > static bool find_event_probe(const char *group, const char *event) > > > { > > > struct dyn_event *ev; > > > struct trace_eprobe *ep; > > > > > > for_each_dyn_event(ev) { > > > if (ev->ops != &eprobe_dyn_event_ops) > > > continue; > > > > > > ep = to_trace_eprobe(ev); > > > if (strcmp(ep->tp.event->class.system, group) == 0 && > > > strcmp(ep->tp.event->call.name, event) == 0) > > > return true; > > > } > > > return false; > > > } > > > > Yeah, but I think this should be done with event_mutex, shouldn't it? > > Probably. I noticed that it was updated under the dyn_event_ops_mutex, > and thought that was enough protection. But I now see the lockdep > assert on the event_mutex in the other functions. > > Is there ever a case where this list is updated without > dyn_event_ops_mutex held?
dyn_event_ops_mutex is for the "dyn_event_ops_list" which manages the list of "struct dyn_event_operations" (e.g. kprobe, uprobe, synthetic).
In kernel/trace/trace_dynevent.c, you can see,
/* Protected by event_mutex */ LIST_HEAD(dyn_event_list);
:)
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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