tracing: add trace_event_read_lock()

[pandora-kernel.git] / kernel / trace / trace_output.c

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index d72b9a6..7136420 100644 (file)
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -14,11 +14,21 @@
 /* must be a power of 2 */
 #define EVENT_HASHSIZE 128
 
-static DEFINE_MUTEX(trace_event_mutex);
+static DECLARE_RWSEM(trace_event_mutex);
 static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly;
 
 static int next_event_type = __TRACE_LAST_TYPE + 1;
 
+void trace_print_seq(struct seq_file *m, struct trace_seq *s)
+{
+       int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
+
+       s->buffer[len] = 0;
+       seq_puts(m, s->buffer);
+
+       trace_seq_init(s);
+}
+
 enum print_line_t trace_print_bprintk_msg_only(struct trace_iterator *iter)
 {
        struct trace_seq *s = &iter->seq;
@@ -84,6 +94,7 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 
        return len;
 }
+EXPORT_SYMBOL_GPL(trace_seq_printf);
 
 int trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
 {
@@ -423,7 +434,7 @@ int trace_print_lat_context(struct trace_iterator *iter)
 
                trace_find_cmdline(entry->pid, comm);
 
-               ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08lx]"
+               ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08llx]"
                                       " %ld.%03ldms (+%ld.%03ldms): ", comm,
                                       entry->pid, iter->cpu, entry->flags,
                                       entry->preempt_count, iter->idx,
@@ -455,6 +466,7 @@ static int task_state_char(unsigned long state)
  * @type: the type of event to look for
  *
  * Returns an event of type @type otherwise NULL
+ * Called with trace_event_read_lock() held.
  */
 struct trace_event *ftrace_find_event(int type)
 {
@@ -464,7 +476,7 @@ struct trace_event *ftrace_find_event(int type)
 
        key = type & (EVENT_HASHSIZE - 1);
 
-       hlist_for_each_entry_rcu(event, n, &event_hash[key], node) {
+       hlist_for_each_entry(event, n, &event_hash[key], node) {
                if (event->type == type)
                        return event;
        }
@@ -472,6 +484,46 @@ struct trace_event *ftrace_find_event(int type)
        return NULL;
 }
 
+static LIST_HEAD(ftrace_event_list);
+
+static int trace_search_list(struct list_head **list)
+{
+       struct trace_event *e;
+       int last = __TRACE_LAST_TYPE;
+
+       if (list_empty(&ftrace_event_list)) {
+               *list = &ftrace_event_list;
+               return last + 1;
+       }
+
+       /*
+        * We used up all possible max events,
+        * lets see if somebody freed one.
+        */
+       list_for_each_entry(e, &ftrace_event_list, list) {
+               if (e->type != last + 1)
+                       break;
+               last++;
+       }
+
+       /* Did we used up all 65 thousand events??? */
+       if ((last + 1) > FTRACE_MAX_EVENT)
+               return 0;
+
+       *list = &e->list;
+       return last + 1;
+}
+
+void trace_event_read_lock(void)
+{
+       down_read(&trace_event_mutex);
+}
+
+void trace_event_read_unlock(void)
+{
+       up_read(&trace_event_mutex);
+}
+
 /**
  * register_ftrace_event - register output for an event type
  * @event: the event type to register
@@ -492,22 +544,42 @@ int register_ftrace_event(struct trace_event *event)
        unsigned key;
        int ret = 0;
 
-       mutex_lock(&trace_event_mutex);
+       down_write(&trace_event_mutex);
 
-       if (!event) {
-               ret = next_event_type++;
+       if (WARN_ON(!event))
                goto out;
-       }
 
-       if (!event->type)
-               event->type = next_event_type++;
-       else if (event->type > __TRACE_LAST_TYPE) {
+       INIT_LIST_HEAD(&event->list);
+
+       if (!event->type) {
+               struct list_head *list = NULL;
+
+               if (next_event_type > FTRACE_MAX_EVENT) {
+
+                       event->type = trace_search_list(&list);
+                       if (!event->type)
+                               goto out;
+
+               } else {
+                       
+                       event->type = next_event_type++;
+                       list = &ftrace_event_list;
+               }
+
+               if (WARN_ON(ftrace_find_event(event->type)))
+                       goto out;
+
+               list_add_tail(&event->list, list);
+
+       } else if (event->type > __TRACE_LAST_TYPE) {
                printk(KERN_WARNING "Need to add type to trace.h\n");
                WARN_ON(1);
-       }
-
-       if (ftrace_find_event(event->type))
                goto out;
+       } else {
+               /* Is this event already used */
+               if (ftrace_find_event(event->type))
+                       goto out;
+       }
 
        if (event->trace == NULL)
                event->trace = trace_nop_print;
@@ -520,14 +592,15 @@ int register_ftrace_event(struct trace_event *event)
 
        key = event->type & (EVENT_HASHSIZE - 1);
 
-       hlist_add_head_rcu(&event->node, &event_hash[key]);
+       hlist_add_head(&event->node, &event_hash[key]);
 
        ret = event->type;
  out:
-       mutex_unlock(&trace_event_mutex);
+       up_write(&trace_event_mutex);
 
        return ret;
 }
+EXPORT_SYMBOL_GPL(register_ftrace_event);
 
 /**
  * unregister_ftrace_event - remove a no longer used event
@@ -535,12 +608,14 @@ int register_ftrace_event(struct trace_event *event)
  */
 int unregister_ftrace_event(struct trace_event *event)
 {
-       mutex_lock(&trace_event_mutex);
+       down_write(&trace_event_mutex);
        hlist_del(&event->node);
-       mutex_unlock(&trace_event_mutex);
+       list_del(&event->list);
+       up_write(&trace_event_mutex);
 
        return 0;
 }
+EXPORT_SYMBOL_GPL(unregister_ftrace_event);
 
 /*
  * Standard events
@@ -834,6 +909,8 @@ static enum print_line_t trace_stack_print(struct trace_iterator *iter,
        trace_assign_type(field, iter->ent);
 
        for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+               if (!field->caller[i])
+                       break;
                if (i) {
                        if (!trace_seq_puts(s, " <= "))
                                goto partial;