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>

1 files changed, 18 insertions, 37 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4c758f146328..398c0e8b332c 100644
--- 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;
 
         /*