trace: fix multiple use of __print_flags and __print_symbolic

[Steven Whitehouse]

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 <swhiteho@xxxxxxxxxx>

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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