tracing: Clean up seqfile code for format file

Remove the nasty hack that marks a pointer's LSB to distinguish common
fields from event fields. Replace it with a more sane approach.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4C6A23C2.9020606@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4c758f1..398c0e8 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -600,21 +600,29 @@ out:
 
 enum {
        FORMAT_HEADER           = 1,
-       FORMAT_PRINTFMT         = 2,
+       FORMAT_FIELD_SEPERATOR  = 2,
+       FORMAT_PRINTFMT         = 3,
 };
 
 static void *f_next(struct seq_file *m, void *v, loff_t *pos)
 {
        struct ftrace_event_call *call = m->private;
        struct ftrace_event_field *field;
-       struct list_head *head;
+       struct list_head *common_head = &ftrace_common_fields;
+       struct list_head *head = trace_get_fields(call);
 
        (*pos)++;
 
        switch ((unsigned long)v) {
        case FORMAT_HEADER:
-               head = &ftrace_common_fields;
+               if (unlikely(list_empty(common_head)))
+                       return NULL;
+
+               field = list_entry(common_head->prev,
+                                  struct ftrace_event_field, link);
+               return field;
 
+       case FORMAT_FIELD_SEPERATOR:
                if (unlikely(list_empty(head)))
                        return NULL;
 
@@ -626,31 +634,10 @@ static void *f_next(struct seq_file *m, void *v, loff_t *pos)
                return NULL;
        }
 
-       head = trace_get_fields(call);
-
-       /*
-        * To separate common fields from event fields, the
-        * LSB is set on the first event field. Clear it in case.
-        */
-       v = (void *)((unsigned long)v & ~1L);
-
        field = v;
-       /*
-        * If this is a common field, and at the end of the list, then
-        * continue with main list.
-        */
-       if (field->link.prev == &ftrace_common_fields) {
-               if (unlikely(list_empty(head)))
-                       return NULL;
-               field = list_entry(head->prev, struct ftrace_event_field, link);
-               /* Set the LSB to notify f_show to print an extra newline */
-               field = (struct ftrace_event_field *)
-                       ((unsigned long)field | 1);
-               return field;
-       }
-
-       /* If we are done tell f_show to print the format */
-       if (field->link.prev == head)
+       if (field->link.prev == common_head)
+               return (void *)FORMAT_FIELD_SEPERATOR;
+       else if (field->link.prev == head)
                return (void *)FORMAT_PRINTFMT;
 
        field = list_entry(field->link.prev, struct ftrace_event_field, link);
@@ -688,22 +675,16 @@ static int f_show(struct seq_file *m, void *v)
                seq_printf(m, "format:\n");
                return 0;
 
+       case FORMAT_FIELD_SEPERATOR:
+               seq_putc(m, '\n');
+               return 0;
+
        case FORMAT_PRINTFMT:
                seq_printf(m, "\nprint fmt: %s\n",
                           call->print_fmt);
                return 0;
        }
 
-       /*
-        * To separate common fields from event fields, the
-        * LSB is set on the first event field. Clear it and
-        * print a newline if it is set.
-        */
-       if ((unsigned long)v & 1) {
-               seq_putc(m, '\n');
-               v = (void *)((unsigned long)v & ~1L);
-       }
-
        field = v;
 
        /*