Here is an updated patch to include the extra call to
trace_seq_init() as requested. This is vs. the latest
-tip tree and fixes the use of multiple __print_flags
and __print_symbolic in a single tracer. Also tested
to ensure its working now:

mount.gfs2-2534  [000]   235.850587: gfs2_glock_queue: 8.7 glock 1:2 dequeue PR
mount.gfs2-2534  [000]   235.850591: gfs2_demote_rq: 8.7 glock 1:0 demote EX to 
NL flags:DI
mount.gfs2-2534  [000]   235.850591: gfs2_glock_queue: 8.7 glock 1:0 dequeue EX
glock_workqueue-2529  [000]   235.850666: gfs2_glock_state_change: 8.7 glock 
1:0 state EX => NL tgt:NL dmt:NL flags:lDpI
glock_workqueue-2529  [000]   235.850672: gfs2_glock_put: 8.7 glock 1:0 state 
NL => IV flags:I

Signed-off-by: Steven Whitehouse <[email protected]>

diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index b4ec83a..1c58f05 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -100,6 +100,7 @@
  *     field = (typeof(field))entry;
  *
  *     p = get_cpu_var(ftrace_event_seq);
+ *     trace_seq_init(p);
  *     ret = trace_seq_printf(s, <TP_printk> "\n");
  *     put_cpu();
  *     if (!ret)
@@ -159,6 +160,7 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int 
flags)    \
        field = (typeof(field))entry;                                   \
                                                                        \
        p = &get_cpu_var(ftrace_event_seq);                             \
+       trace_seq_init(p);                                              \
        ret = trace_seq_printf(s, #call ": " print);                    \
        put_cpu();                                                      \
        if (!ret)                                                       \
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index c12d95d..ac6ced1 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -222,10 +222,9 @@ ftrace_print_flags_seq(struct trace_seq *p, const char 
*delim,
 {
        unsigned long mask;
        const char *str;
+       const char *ret = p->buffer + p->len;
        int i;
 
-       trace_seq_init(p);
-
        for (i = 0;  flag_array[i].name && flags; i++) {
 
                mask = flag_array[i].mask;
@@ -248,7 +247,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char 
*delim,
 
        trace_seq_putc(p, 0);
 
-       return p->buffer;
+       return ret;
 }
 
 const char *
@@ -256,8 +255,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long 
val,
                         const struct trace_print_flags *symbol_array)
 {
        int i;
-
-       trace_seq_init(p);
+       const char *ret = p->buffer + p->len;
 
        for (i = 0;  symbol_array[i].name; i++) {
 
@@ -273,7 +271,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long 
val,
                
        trace_seq_putc(p, 0);
 
-       return p->buffer;
+       return ret;
 }
 
 #ifdef CONFIG_KRETPROBES


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