On Mon, 17 Jun 2019 21:56:43 -0400 Steven Rostedt <rost...@goodmis.org> wrote:
> On Sat, 1 Jun 2019 00:18:16 +0900 > Masami Hiramatsu <mhira...@kernel.org> wrote: > > > Split the trace_event related data from trace_probe data structure > > and introduce trace_probe_event data structure for its folder. > > This trace_probe_event data structure can have multiple trace_probe. > > > > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org> > > --- > > kernel/trace/trace_kprobe.c | 99 ++++++++++++++++++++++------------- > > kernel/trace/trace_probe.c | 53 +++++++++++++------ > > kernel/trace/trace_probe.h | 48 +++++++++++++---- > > kernel/trace/trace_uprobe.c | 123 > > +++++++++++++++++++++++++++++-------------- > > 4 files changed, 221 insertions(+), 102 deletions(-) > > > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > > index 9d483ad9bb6c..633edb88cd0e 100644 > > --- a/kernel/trace/trace_kprobe.c > > +++ b/kernel/trace/trace_kprobe.c > > @@ -180,9 +180,17 @@ unsigned long trace_kprobe_address(struct trace_kprobe > > *tk) > > return addr; > > } > > > > +static nokprobe_inline struct trace_kprobe * > > +trace_kprobe_primary_from_call(struct trace_event_call *call) > > +{ > > + struct trace_probe *tp = trace_probe_primary_from_call(call); > > + > > + return container_of(tp, struct trace_kprobe, tp); > > > Hmm, is there a possibility that trace_probe_primary_from_call() may > not have a primary? Good question! Of course if given event_call is not a kprobe event, it doesn't have primary (or any) trace_probe. But that must not happen unless user misuses it. And that list never be the empty, when the last trace probe is released, the event_call also unregistered and released. See unregister_trace_kprobe() for details. If there is no siblings on the list, the event_call is also unregistered before unregistering kprobes, and after unregistering kprobes the list is unlinked. (Note that unregister_kprobe() will wait a quiescence period before return. This means all probe handlers are done before that.) > > +} > > + > > bool trace_kprobe_on_func_entry(struct trace_event_call *call) > > { > > - struct trace_kprobe *tk = (struct trace_kprobe *)call->data; > > + struct trace_kprobe *tk = trace_kprobe_primary_from_call(call); > > > > return kprobe_on_func_entry(tk->rp.kp.addr, > > tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name, > > @@ -191,7 +199,7 @@ bool trace_kprobe_on_func_entry(struct trace_event_call > > *call) > > > > bool trace_kprobe_error_injectable(struct trace_event_call *call) > > { > > - struct trace_kprobe *tk = (struct trace_kprobe *)call->data; > > + struct trace_kprobe *tk = trace_kprobe_primary_from_call(call); > > > > return within_error_injection_list(trace_kprobe_address(tk)); > > } > > @@ -295,28 +303,40 @@ static inline int __enable_trace_kprobe(struct > > trace_kprobe *tk) > > * Enable trace_probe > > * if the file is NULL, enable "perf" handler, or enable "trace" handler. > > */ > > -static int > > -enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) > > +static int enable_trace_kprobe(struct trace_event_call *call, > > + struct trace_event_file *file) > > { > > - bool enabled = trace_probe_is_enabled(&tk->tp); > > - int ret = 0; > > + struct trace_probe *pos, *tp = trace_probe_primary_from_call(call); > > + struct trace_kprobe *tk; > > + bool enabled = trace_probe_is_enabled(tp); > > + int ret = 0, ecode; > > > > if (file) { > > - ret = trace_probe_add_file(&tk->tp, file); > > + ret = trace_probe_add_file(tp, file); > > if (ret) > > return ret; > > } else > > - trace_probe_set_flag(&tk->tp, TP_FLAG_PROFILE); > > + trace_probe_set_flag(tp, TP_FLAG_PROFILE); > > > > if (enabled) > > return 0; > > > > - ret = __enable_trace_kprobe(tk); > > - if (ret) { > > + enabled = false; > > + list_for_each_entry(pos, trace_probe_probe_list(tp), list) { > > + tk = container_of(pos, struct trace_kprobe, tp); > > + ecode = __enable_trace_kprobe(tk); > > + if (ecode) > > + ret = ecode; /* Save the last error code */ > > + else > > + enabled = true; > > So, if we have some enabled but return an error code, what should a > caller think of that? Wouldn't it be an inconsistent state? Oops, good catch! This part is related to caller (ftrace/perf) so should be more careful. Usually, kprobe enablement should not fail. If one of them has gone (like a probe on unloaded module), it can be fail but that should be ignored. I would like to add some additional check so that - If all kprobes are on the module which is unloaded, enablement must be failed and return error. - If any kprobe is enabled, and others are on non-exist modules, it should succeeded and return OK. - If any kprobe caused an error not because of unloaded module, all other enablement should be canceled and return error. Is that OK for you? Thank you, > > -- Steve > > > > + } > > + > > + if (!enabled) { > > + /* No probe is enabled. Roll back */ > > if (file) > > - trace_probe_remove_file(&tk->tp, file); > > + trace_probe_remove_file(tp, file); > > else > > - trace_probe_clear_flag(&tk->tp, TP_FLAG_PROFILE); > > + trace_probe_clear_flag(tp, TP_FLAG_PROFILE); > > } > > > > > > > > +static inline struct trace_probe_event * > > +trace_probe_event_from_call(struct trace_event_call *event_call) > > +{ > > + return container_of(event_call, struct trace_probe_event, call); > > +} > > + > > +static inline struct trace_probe * > > +trace_probe_primary_from_call(struct trace_event_call *call) > > +{ > > + struct trace_probe_event *tpe = trace_probe_event_from_call(call); > > + > > + return list_first_entry(&tpe->probes, struct trace_probe, list); > > +} > > + > > +static inline struct list_head *trace_probe_probe_list(struct trace_probe > > *tp) > > +{ > > + return &tp->event->probes; > > } > > -- Masami Hiramatsu <mhira...@kernel.org>