tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints

Register/unregister tracepoint probes with struct tracepoint pointer
rather than tracepoint name.

This change, which vastly simplifies tracepoint.c, has been proposed by
Steven Rostedt. It also removes 8.8kB (mostly of text) to the vmlinux
size.

From this point on, the tracers need to pass a struct tracepoint pointer
to probe register/unregister. A probe can now only be connected to a
tracepoint that exists. Moreover, tracers are responsible for
unregistering the probe before the module containing its associated
tracepoint is unloaded.

   text    data     bss     dec     hex filename
10443444        4282528 10391552        25117524        17f4354 vmlinux.orig
10434930        4282848 10391552        25109330        17f2352 vmlinux

Link: http://lkml.kernel.org/r/1396992381-23785-2-git-send-email-mathieu.desnoyers@efficios.com

CC: Ingo Molnar <mingo@kernel.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Frank Ch. Eigler <fche@redhat.com>
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
[ SDR - fixed return val in void func in tracepoint_module_going() ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 13 insertions, 8 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d021d21dd150..903ae28962be 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -341,7 +341,7 @@ static struct trace_kprobe *find_trace_kprobe(const char *event,
 	struct trace_kprobe *tk;
 
 	list_for_each_entry(tk, &probe_list, list)
-		if (strcmp(tk->tp.call.name, event) == 0 &&
+		if (strcmp(ftrace_event_name(&tk->tp.call), event) == 0 &&
 		    strcmp(tk->tp.call.class->system, group) == 0)
 			return tk;
 	return NULL;
@@ -516,7 +516,8 @@ static int register_trace_kprobe(struct trace_kprobe *tk)
 	mutex_lock(&probe_lock);
 
 	/* Delete old (same name) event if exist */
-	old_tk = find_trace_kprobe(tk->tp.call.name, tk->tp.call.class->system);
+	old_tk = find_trace_kprobe(ftrace_event_name(&tk->tp.call),
+			tk->tp.call.class->system);
 	if (old_tk) {
 		ret = unregister_trace_kprobe(old_tk);
 		if (ret < 0)
@@ -564,7 +565,8 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
 			if (ret)
 				pr_warning("Failed to re-register probe %s on"
 					   "%s: %d\n",
-					   tk->tp.call.name, mod->name, ret);
+					   ftrace_event_name(&tk->tp.call),
+					   mod->name, ret);
 		}
 	}
 	mutex_unlock(&probe_lock);
@@ -818,7 +820,8 @@ static int probes_seq_show(struct seq_file *m, void *v)
 	int i;
 
 	seq_printf(m, "%c", trace_kprobe_is_return(tk) ? 'r' : 'p');
-	seq_printf(m, ":%s/%s", tk->tp.call.class->system, tk->tp.call.name);
+	seq_printf(m, ":%s/%s", tk->tp.call.class->system,
+			ftrace_event_name(&tk->tp.call));
 
 	if (!tk->symbol)
 		seq_printf(m, " 0x%p", tk->rp.kp.addr);
@@ -876,7 +879,8 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
 {
 	struct trace_kprobe *tk = v;
 
-	seq_printf(m, "  %-44s %15lu %15lu\n", tk->tp.call.name, tk->nhit,
+	seq_printf(m, "  %-44s %15lu %15lu\n",
+		   ftrace_event_name(&tk->tp.call), tk->nhit,
 		   tk->rp.kp.nmissed);
 
 	return 0;
@@ -1011,7 +1015,7 @@ print_kprobe_event(struct trace_iterator *iter, int flags,
 	field = (struct kprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
 
-	if (!trace_seq_printf(s, "%s: (", tp->call.name))
+	if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
 		goto partial;
 
 	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
@@ -1047,7 +1051,7 @@ print_kretprobe_event(struct trace_iterator *iter, int flags,
 	field = (struct kretprobe_trace_entry_head *)iter->ent;
 	tp = container_of(event, struct trace_probe, call.event);
 
-	if (!trace_seq_printf(s, "%s: (", tp->call.name))
+	if (!trace_seq_printf(s, "%s: (", ftrace_event_name(&tp->call)))
 		goto partial;
 
 	if (!seq_print_ip_sym(s, field->ret_ip, flags | TRACE_ITER_SYM_OFFSET))
@@ -1286,7 +1290,8 @@ static int register_kprobe_event(struct trace_kprobe *tk)
 	call->data = tk;
 	ret = trace_add_event_call(call);
 	if (ret) {
-		pr_info("Failed to register kprobe event: %s\n", call->name);
+		pr_info("Failed to register kprobe event: %s\n",
+			ftrace_event_name(call));
 		kfree(call->print_fmt);
 		unregister_ftrace_event(&call->event);
 	}