tracing/filters: move preds into event_filter object

Create a new event_filter object, and move the pred-related members
out of the call and subsystem objects and into the filter object - the
details of the filter implementation don't need to be exposed in the
call and subsystem in any case, and it will also help make the new
parser implementation a little cleaner.

[ Impact: refactor trace-filter code to prepare for new features ]

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
Cc: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <1240905887.6416.119.camel@tropicana>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 74 insertions, 46 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7d55bcf50e49..1fb7d6ccadf4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -731,12 +731,16 @@ struct ftrace_event_field {
         int                     size;
 };
 
+struct event_filter {
+        int                     n_preds;
+        struct filter_pred      **preds;
+};
+
 struct event_subsystem {
         struct list_head        list;
         const char              *name;
         struct dentry           *entry;
-        int                     n_preds;
-        struct filter_pred      **preds;
+        void                    *filter;
 };
 
 struct filter_pred;
@@ -774,7 +778,7 @@ filter_check_discard(struct ftrace_event_call *call, void *rec,
                      struct ring_buffer *buffer,
                      struct ring_buffer_event *event)
 {
-        if (unlikely(call->n_preds) && !filter_match_preds(call, rec)) {
+        if (unlikely(call->filter_active) && !filter_match_preds(call, rec)) {
                 ring_buffer_discard_commit(buffer, event);
                 return 1;
         }
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index be4d3a437c17..1cd1f37373dd 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -757,8 +757,7 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 
         list_add(&system->list, &event_subsystems);
 
-        system->preds = NULL;
-        system->n_preds = 0;
+        system->filter = NULL;
 
         entry = debugfs_create_file("filter", 0644, system->entry, system,
                                     &ftrace_subsystem_filter_fops);
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 65418288f957..1e861eca3d02 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -93,11 +93,12 @@ static int filter_pred_none(struct filter_pred *pred, void *event)
 /* return 1 if event matches, 0 otherwise (discard) */
 int filter_match_preds(struct ftrace_event_call *call, void *rec)
 {
+        struct event_filter *filter = call->filter;
         int i, matched, and_failed = 0;
         struct filter_pred *pred;
 
-        for (i = 0; i < call->n_preds; i++) {
-                pred = call->preds[i];
+        for (i = 0; i < filter->n_preds; i++) {
+                pred = filter->preds[i];
                 if (and_failed && !pred->or)
                         continue;
                 matched = pred->fn(pred, rec);
@@ -115,20 +116,20 @@ int filter_match_preds(struct ftrace_event_call *call, void *rec)
 }
 EXPORT_SYMBOL_GPL(filter_match_preds);
 
-static void __filter_print_preds(struct filter_pred **preds, int n_preds,
+static void __filter_print_preds(struct event_filter *filter,
                                  struct trace_seq *s)
 {
-        char *field_name;
         struct filter_pred *pred;
+        char *field_name;
         int i;
 
-        if (!n_preds) {
+        if (!filter || !filter->n_preds) {
                 trace_seq_printf(s, "none\n");
                 return;
         }
 
-        for (i = 0; i < n_preds; i++) {
-                pred = preds[i];
+        for (i = 0; i < filter->n_preds; i++) {
+                pred = filter->preds[i];
                 field_name = pred->field_name;
                 if (i)
                         trace_seq_printf(s, pred->or ? "|| " : "&& ");
@@ -144,7 +145,7 @@ static void __filter_print_preds(struct filter_pred **preds, int n_preds,
 void filter_print_preds(struct ftrace_event_call *call, struct trace_seq *s)
 {
         mutex_lock(&filter_mutex);
-        __filter_print_preds(call->preds, call->n_preds, s);
+        __filter_print_preds(call->filter, s);
         mutex_unlock(&filter_mutex);
 }
 
@@ -152,7 +153,7 @@ void filter_print_subsystem_preds(struct event_subsystem *system,
                                   struct trace_seq *s)
 {
         mutex_lock(&filter_mutex);
-        __filter_print_preds(system->preds, system->n_preds, s);
+        __filter_print_preds(system->filter, s);
         mutex_unlock(&filter_mutex);
 }
 
@@ -200,12 +201,14 @@ static int filter_set_pred(struct filter_pred *dest,
 
 static void __filter_disable_preds(struct ftrace_event_call *call)
 {
+        struct event_filter *filter = call->filter;
         int i;
 
-        call->n_preds = 0;
+        call->filter_active = 0;
+        filter->n_preds = 0;
 
         for (i = 0; i < MAX_FILTER_PRED; i++)
-                call->preds[i]->fn = filter_pred_none;
+                filter->preds[i]->fn = filter_pred_none;
 }
 
 void filter_disable_preds(struct ftrace_event_call *call)
@@ -217,32 +220,39 @@ void filter_disable_preds(struct ftrace_event_call *call)
 
 int init_preds(struct ftrace_event_call *call)
 {
+        struct event_filter *filter;
         struct filter_pred *pred;
         int i;
 
-        call->n_preds = 0;
-
-        call->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred), GFP_KERNEL);
-        if (!call->preds)
+        filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
+        if (!call->filter)
                 return -ENOMEM;
 
+        call->filter_active = 0;
+        filter->n_preds = 0;
+
+        filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred), GFP_KERNEL);
+        if (!filter->preds)
+                goto oom;
+
         for (i = 0; i < MAX_FILTER_PRED; i++) {
                 pred = kzalloc(sizeof(*pred), GFP_KERNEL);
                 if (!pred)
                         goto oom;
                 pred->fn = filter_pred_none;
-                call->preds[i] = pred;
+                filter->preds[i] = pred;
         }
 
         return 0;
 
 oom:
         for (i = 0; i < MAX_FILTER_PRED; i++) {
-                if (call->preds[i])
-                        filter_free_pred(call->preds[i]);
+                if (filter->preds[i])
+                        filter_free_pred(filter->preds[i]);
         }
-        kfree(call->preds);
-        call->preds = NULL;
+        kfree(filter->preds);
+        kfree(call->filter);
+        call->filter = NULL;
 
         return -ENOMEM;
 }
@@ -250,15 +260,16 @@ EXPORT_SYMBOL_GPL(init_preds);
 
 static void __filter_free_subsystem_preds(struct event_subsystem *system)
 {
+        struct event_filter *filter = system->filter;
         struct ftrace_event_call *call;
         int i;
 
-        if (system->n_preds) {
-                for (i = 0; i < system->n_preds; i++)
-                        filter_free_pred(system->preds[i]);
-                kfree(system->preds);
-                system->preds = NULL;
-                system->n_preds = 0;
+        if (filter && filter->n_preds) {
+                for (i = 0; i < filter->n_preds; i++)
+                        filter_free_pred(filter->preds[i]);
+                kfree(filter->preds);
+                kfree(filter);
+                system->filter = NULL;
         }
 
         list_for_each_entry(call, &ftrace_events, list) {
@@ -281,21 +292,23 @@ static int filter_add_pred_fn(struct ftrace_event_call *call,
                               struct filter_pred *pred,
                               filter_pred_fn_t fn)
 {
+        struct event_filter *filter = call->filter;
         int idx, err;
 
-        if (call->n_preds && !pred->compound)
+        if (filter->n_preds && !pred->compound)
                 __filter_disable_preds(call);
 
-        if (call->n_preds == MAX_FILTER_PRED)
+        if (filter->n_preds == MAX_FILTER_PRED)
                 return -ENOSPC;
 
-        idx = call->n_preds;
-        filter_clear_pred(call->preds[idx]);
-        err = filter_set_pred(call->preds[idx], pred, fn);
+        idx = filter->n_preds;
+        filter_clear_pred(filter->preds[idx]);
+        err = filter_set_pred(filter->preds[idx], pred, fn);
         if (err)
                 return err;
 
-        call->n_preds++;
+        filter->n_preds++;
+        call->filter_active = 1;
 
         return 0;
 }
@@ -366,29 +379,41 @@ int filter_add_pred(struct ftrace_event_call *call, struct filter_pred *pred)
 int filter_add_subsystem_pred(struct event_subsystem *system,
                               struct filter_pred *pred)
 {
+        struct event_filter *filter = system->filter;
         struct ftrace_event_call *call;
 
         mutex_lock(&filter_mutex);
 
-        if (system->n_preds && !pred->compound)
+        if (filter && filter->n_preds && !pred->compound) {
                 __filter_free_subsystem_preds(system);
+                filter = NULL;
+        }
 
-        if (!system->n_preds) {
-                system->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
+        if (!filter) {
+                system->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
+                if (!system->filter) {
+                        mutex_unlock(&filter_mutex);
+                        return -ENOMEM;
+                }
+                filter = system->filter;
+                filter->preds = kzalloc(MAX_FILTER_PRED * sizeof(pred),
                                         GFP_KERNEL);
-                if (!system->preds) {
+
+                if (!filter->preds) {
+                        kfree(system->filter);
+                        system->filter = NULL;
                         mutex_unlock(&filter_mutex);
                         return -ENOMEM;
                 }
         }
 
-        if (system->n_preds == MAX_FILTER_PRED) {
+        if (filter->n_preds == MAX_FILTER_PRED) {
                 mutex_unlock(&filter_mutex);
                 return -ENOSPC;
         }
 
-        system->preds[system->n_preds] = pred;
-        system->n_preds++;
+        filter->preds[filter->n_preds] = pred;
+        filter->n_preds++;
 
         list_for_each_entry(call, &ftrace_events, list) {
                 int err;
@@ -401,8 +426,8 @@ int filter_add_subsystem_pred(struct event_subsystem *system,
 
                 err = __filter_add_pred(call, pred);
                 if (err == -ENOMEM) {
-                        system->preds[system->n_preds] = NULL;
-                        system->n_preds--;
+                        filter->preds[filter->n_preds] = NULL;
+                        filter->n_preds--;
                         mutex_unlock(&filter_mutex);
                         return err;
                 }