tracing: Create class struct for events

This patch creates a ftrace_event_class struct that event structs point to.
This class struct will be made to hold information to modify the
events. Currently the class struct only holds the events system name.

This patch slightly increases the size, but this change lays the ground work
of other changes to make the footprint of tracepoints smaller.

With 82 standard tracepoints, and 618 system call tracepoints
(two tracepoints per syscall: enter and exit):

   text	   data	    bss	    dec	    hex	filename
4913961	1088356	 861512	6863829	 68bbd5	vmlinux.orig
4914025	1088868	 861512	6864405	 68be15	vmlinux.class

This patch also cleans up some stale comments in ftrace.h.

v2: Fixed missing semi-colon in macro.

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

5 files changed, 28 insertions, 20 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c697c7043349..2f54b48d3632 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -176,10 +176,10 @@ static int __ftrace_set_clr_event(const char *match, const char *sub,
 
                 if (match &&
                     strcmp(match, call->name) != 0 &&
-                    strcmp(match, call->system) != 0)
+                    strcmp(match, call->class->system) != 0)
                         continue;
 
-                if (sub && strcmp(sub, call->system) != 0)
+                if (sub && strcmp(sub, call->class->system) != 0)
                         continue;
 
                 if (event && strcmp(event, call->name) != 0)
@@ -355,8 +355,8 @@ static int t_show(struct seq_file *m, void *v)
 {
         struct ftrace_event_call *call = v;
 
-        if (strcmp(call->system, TRACE_SYSTEM) != 0)
-                seq_printf(m, "%s:", call->system);
+        if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
+                seq_printf(m, "%s:", call->class->system);
         seq_printf(m, "%s\n", call->name);
 
         return 0;
@@ -453,7 +453,7 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                 if (!call->name || !call->regfunc)
                         continue;
 
-                if (system && strcmp(call->system, system) != 0)
+                if (system && strcmp(call->class->system, system) != 0)
                         continue;
 
                 /*
@@ -925,8 +925,8 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
          * If the trace point header did not define TRACE_SYSTEM
          * then the system would be called "TRACE_SYSTEM".
          */
-        if (strcmp(call->system, TRACE_SYSTEM) != 0)
-                d_events = event_subsystem_dir(call->system, d_events);
+        if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
+                d_events = event_subsystem_dir(call->class->system, d_events);
 
         call->dir = debugfs_create_dir(call->name, d_events);
         if (!call->dir) {
@@ -1041,7 +1041,7 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
         list_del(&call->list);
         trace_destroy_fields(call);
         destroy_preds(call);
-        remove_subsystem_dir(call->system);
+        remove_subsystem_dir(call->class->system);
 }
 
 /* Remove an event_call */
@@ -1399,8 +1399,8 @@ static __init void event_trace_self_tests(void)
  * syscalls as we test.
  */
 #ifndef CONFIG_EVENT_TRACE_TEST_SYSCALLS
-                if (call->system &&
-                    strcmp(call->system, "syscalls") == 0)
+                if (call->class->system &&
+                    strcmp(call->class->system, "syscalls") == 0)
                         continue;
 #endif
 
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 88c0b6dbd7fe..ca329603d0bf 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -628,7 +628,7 @@ static int init_subsystem_preds(struct event_subsystem *system)
                 if (!call->define_fields)
                         continue;
 
-                if (strcmp(call->system, system->name) != 0)
+                if (strcmp(call->class->system, system->name) != 0)
                         continue;
 
                 err = init_preds(call);
@@ -647,7 +647,7 @@ static void filter_free_subsystem_preds(struct event_subsystem *system)
                 if (!call->define_fields)
                         continue;
 
-                if (strcmp(call->system, system->name) != 0)
+                if (strcmp(call->class->system, system->name) != 0)
                         continue;
 
                 filter_disable_preds(call);
@@ -1252,7 +1252,7 @@ static int replace_system_preds(struct event_subsystem *system,
                 if (!call->define_fields)
                         continue;
 
-                if (strcmp(call->system, system->name) != 0)
+                if (strcmp(call->class->system, system->name) != 0)
                         continue;
 
                 /* try to see if the filter can be applied */
diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index e091f64ba6ce..7f16e2163817 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -18,6 +18,10 @@
 #undef TRACE_SYSTEM
 #define TRACE_SYSTEM    ftrace
 
+struct ftrace_event_class event_class_ftrace = {
+        .system                 = __stringify(TRACE_SYSTEM),
+};
+
 /* not needed for this file */
 #undef __field_struct
 #define __field_struct(type, item)
@@ -160,7 +164,7 @@ __attribute__((__aligned__(4)))						\
 __attribute__((section("_ftrace_events"))) event_##call = {             \
         .name                   = #call,                                \
         .id                     = type,                                 \
-        .system                 = __stringify(TRACE_SYSTEM),            \
+        .class                  = &event_class_ftrace,                  \
         .raw_init               = ftrace_raw_init_event,                \
         .print_fmt              = print,                                \
         .define_fields          = ftrace_define_fields_##call,          \
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 1251e367bae9..eda220bf2065 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -332,8 +332,8 @@ static struct trace_probe *alloc_trace_probe(const char *group,
                 goto error;
         }
 
-        tp->call.system = kstrdup(group, GFP_KERNEL);
-        if (!tp->call.system)
+        tp->call.class->system = kstrdup(group, GFP_KERNEL);
+        if (!tp->call.class->system)
                 goto error;
 
         INIT_LIST_HEAD(&tp->list);
@@ -361,7 +361,7 @@ static void free_trace_probe(struct trace_probe *tp)
         for (i = 0; i < tp->nr_args; i++)
                 free_probe_arg(&tp->args[i]);
 
-        kfree(tp->call.system);
+        kfree(tp->call.class->system);
         kfree(tp->call.name);
         kfree(tp->symbol);
         kfree(tp);
@@ -374,7 +374,7 @@ static struct trace_probe *find_probe_event(const char *event,
 
         list_for_each_entry(tp, &probe_list, list)
                 if (strcmp(tp->call.name, event) == 0 &&
-                    strcmp(tp->call.system, group) == 0)
+                    strcmp(tp->call.class->system, group) == 0)
                         return tp;
         return NULL;
 }
@@ -399,7 +399,7 @@ static int register_trace_probe(struct trace_probe *tp)
         mutex_lock(&probe_lock);
 
         /* register as an event */
-        old_tp = find_probe_event(tp->call.name, tp->call.system);
+        old_tp = find_probe_event(tp->call.name, tp->call.class->system);
         if (old_tp) {
                 /* delete old event */
                 unregister_trace_probe(old_tp);
@@ -798,7 +798,7 @@ static int probes_seq_show(struct seq_file *m, void *v)
         char buf[MAX_ARGSTR_LEN + 1];
 
         seq_printf(m, "%c", probe_is_return(tp) ? 'r' : 'p');
-        seq_printf(m, ":%s/%s", tp->call.system, tp->call.name);
+        seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);
 
         if (!tp->symbol)
                 seq_printf(m, " 0x%p", tp->rp.kp.addr);
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 4d6d711717f2..d036a74a64f3 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -15,6 +15,10 @@ static int sys_refcount_exit;
 static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
 static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
 
+struct ftrace_event_class event_class_syscalls = {
+        .system                 = "syscalls"
+};
+
 extern unsigned long __start_syscalls_metadata[];
 extern unsigned long __stop_syscalls_metadata[];