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, 32 insertions, 23 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 83a4378dc5e0..3ddfd8f62c05 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -223,24 +223,25 @@ int ftrace_event_reg(struct ftrace_event_call *call,
 {
 	struct ftrace_event_file *file = data;
 
+	WARN_ON(!(call->flags & TRACE_EVENT_FL_TRACEPOINT));
 	switch (type) {
 	case TRACE_REG_REGISTER:
-		return tracepoint_probe_register(call->name,
+		return tracepoint_probe_register(call->tp,
 						 call->class->probe,
 						 file);
 	case TRACE_REG_UNREGISTER:
-		tracepoint_probe_unregister(call->name,
+		tracepoint_probe_unregister(call->tp,
 					    call->class->probe,
 					    file);
 		return 0;
 
 #ifdef CONFIG_PERF_EVENTS
 	case TRACE_REG_PERF_REGISTER:
-		return tracepoint_probe_register(call->name,
+		return tracepoint_probe_register(call->tp,
 						 call->class->perf_probe,
 						 call);
 	case TRACE_REG_PERF_UNREGISTER:
-		tracepoint_probe_unregister(call->name,
+		tracepoint_probe_unregister(call->tp,
 					    call->class->perf_probe,
 					    call);
 		return 0;
@@ -352,7 +353,7 @@ static int __ftrace_event_enable_disable(struct ftrace_event_file *file,
 			if (ret) {
 				tracing_stop_cmdline_record();
 				pr_info("event trace: Could not enable event "
-					"%s\n", call->name);
+					"%s\n", ftrace_event_name(call));
 				break;
 			}
 			set_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
@@ -481,27 +482,29 @@ __ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
 {
 	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
+	const char *name;
 	int ret = -EINVAL;
 
 	list_for_each_entry(file, &tr->events, list) {
 
 		call = file->event_call;
+		name = ftrace_event_name(call);
 
-		if (!call->name || !call->class || !call->class->reg)
+		if (!name || !call->class || !call->class->reg)
 			continue;
 
 		if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
 			continue;
 
 		if (match &&
-		    strcmp(match, call->name) != 0 &&
+		    strcmp(match, name) != 0 &&
 		    strcmp(match, call->class->system) != 0)
 			continue;
 
 		if (sub && strcmp(sub, call->class->system) != 0)
 			continue;
 
-		if (event && strcmp(event, call->name) != 0)
+		if (event && strcmp(event, name) != 0)
 			continue;
 
 		ftrace_event_enable_disable(file, set);
@@ -699,7 +702,7 @@ static int t_show(struct seq_file *m, void *v)
 
 	if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
 		seq_printf(m, "%s:", call->class->system);
-	seq_printf(m, "%s\n", call->name);
+	seq_printf(m, "%s\n", ftrace_event_name(call));
 
 	return 0;
 }
@@ -792,7 +795,7 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
 	mutex_lock(&event_mutex);
 	list_for_each_entry(file, &tr->events, list) {
 		call = file->event_call;
-		if (!call->name || !call->class || !call->class->reg)
+		if (!ftrace_event_name(call) || !call->class || !call->class->reg)
 			continue;
 
 		if (system && strcmp(call->class->system, system->name) != 0)
@@ -907,7 +910,7 @@ static int f_show(struct seq_file *m, void *v)
 
 	switch ((unsigned long)v) {
 	case FORMAT_HEADER:
-		seq_printf(m, "name: %s\n", call->name);
+		seq_printf(m, "name: %s\n", ftrace_event_name(call));
 		seq_printf(m, "ID: %d\n", call->event.type);
 		seq_printf(m, "format:\n");
 		return 0;
@@ -1527,6 +1530,7 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
 	struct trace_array *tr = file->tr;
 	struct list_head *head;
 	struct dentry *d_events;
+	const char *name;
 	int ret;
 
 	/*
@@ -1540,10 +1544,11 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
 	} else
 		d_events = parent;
 
-	file->dir = debugfs_create_dir(call->name, d_events);
+	name = ftrace_event_name(call);
+	file->dir = debugfs_create_dir(name, d_events);
 	if (!file->dir) {
 		pr_warning("Could not create debugfs '%s' directory\n",
-			   call->name);
+			   name);
 		return -1;
 	}
 
@@ -1567,7 +1572,7 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
 		ret = call->class->define_fields(call);
 		if (ret < 0) {
 			pr_warning("Could not initialize trace point"
-				   " events/%s\n", call->name);
+				   " events/%s\n", name);
 			return -1;
 		}
 	}
@@ -1631,15 +1636,17 @@ static void event_remove(struct ftrace_event_call *call)
 static int event_init(struct ftrace_event_call *call)
 {
 	int ret = 0;
+	const char *name;
 
-	if (WARN_ON(!call->name))
+	name = ftrace_event_name(call);
+	if (WARN_ON(!name))
 		return -EINVAL;
 
 	if (call->class->raw_init) {
 		ret = call->class->raw_init(call);
 		if (ret < 0 && ret != -ENOSYS)
 			pr_warn("Could not initialize trace events/%s\n",
-				call->name);
+				name);
 	}
 
 	return ret;
@@ -1885,7 +1892,7 @@ __trace_add_event_dirs(struct trace_array *tr)
 		ret = __trace_add_new_event(call, tr);
 		if (ret < 0)
 			pr_warning("Could not create directory for event %s\n",
-				   call->name);
+				   ftrace_event_name(call));
 	}
 }
 
@@ -1894,18 +1901,20 @@ find_event_file(struct trace_array *tr, const char *system,  const char *event)
 {
 	struct ftrace_event_file *file;
 	struct ftrace_event_call *call;
+	const char *name;
 
 	list_for_each_entry(file, &tr->events, list) {
 
 		call = file->event_call;
+		name = ftrace_event_name(call);
 
-		if (!call->name || !call->class || !call->class->reg)
+		if (!name || !call->class || !call->class->reg)
 			continue;
 
 		if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
 			continue;
 
-		if (strcmp(event, call->name) == 0 &&
+		if (strcmp(event, name) == 0 &&
 		    strcmp(system, call->class->system) == 0)
 			return file;
 	}
@@ -1973,7 +1982,7 @@ event_enable_print(struct seq_file *m, unsigned long ip,
 	seq_printf(m, "%s:%s:%s",
 		   data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
 		   data->file->event_call->class->system,
-		   data->file->event_call->name);
+		   ftrace_event_name(data->file->event_call));
 
 	if (data->count == -1)
 		seq_printf(m, ":unlimited\n");
@@ -2193,7 +2202,7 @@ __trace_early_add_event_dirs(struct trace_array *tr)
 		ret = event_create_dir(tr->event_dir, file);
 		if (ret < 0)
 			pr_warning("Could not create directory for event %s\n",
-				   file->event_call->name);
+				   ftrace_event_name(file->event_call));
 	}
 }
 
@@ -2217,7 +2226,7 @@ __trace_early_add_events(struct trace_array *tr)
 		ret = __trace_early_add_new_event(call, tr);
 		if (ret < 0)
 			pr_warning("Could not create early event %s\n",
-				   call->name);
+				   ftrace_event_name(call));
 	}
 }
 
@@ -2549,7 +2558,7 @@ static __init void event_trace_self_tests(void)
 			continue;
 #endif
 
-		pr_info("Testing event %s: ", call->name);
+		pr_info("Testing event %s: ", ftrace_event_name(call));
 
 		/*
 		 * If an event is already enabled, someone is using