[RFC PATCH v2 3/3] libtraceevent: use the new prev_state_char instead in tracepoint sched_switch

[Ze Gao <zegao2021@gmail.com>]

Since the sched_switch tracepoint introduces a new variable to
report sched-out task state in symbolic char, we switch to use
that instead to spare from knowing internal implementations
in kernel.

Signed-off-by: Ze Gao <zegao@tencent.com>
---
 plugins/plugin_sched_switch.c | 29 ++++-------------------------
 1 file changed, 4 insertions(+), 25 deletions(-)

diff --git a/plugins/plugin_sched_switch.c b/plugins/plugin_sched_switch.c
index 8752cae..5dbdc28 100644
--- a/plugins/plugin_sched_switch.c
+++ b/plugins/plugin_sched_switch.c
@@ -9,27 +9,6 @@
 #include "event-parse.h"
 #include "trace-seq.h"
 
-static void write_state(struct trace_seq *s, int val)
-{
-	const char states[] = "SDTtZXxW";
-	int found = 0;
-	int i;
-
-	for (i = 0; i < (sizeof(states) - 1); i++) {
-		if (!(val & (1 << i)))
-			continue;
-
-		if (found)
-			trace_seq_putc(s, '|');
-
-		found = 1;
-		trace_seq_putc(s, states[i]);
-	}
-
-	if (!found)
-		trace_seq_putc(s, 'R');
-}
-
 static void write_and_save_comm(struct tep_format_field *field,
 				struct tep_record *record,
 				struct trace_seq *s, int pid)
@@ -97,10 +76,10 @@ static int sched_switch_handler(struct trace_seq *s,
 	trace_seq_printf(s, "%lld ", val);
 
 	if (tep_get_field_val(s, event, "prev_prio", record, &val, 1) == 0)
-		trace_seq_printf(s, "[%d] ", (int) val);
+		trace_seq_printf(s, "[%d] ", (short) val);
 
-	if (tep_get_field_val(s,  event, "prev_state", record, &val, 1) == 0)
-		write_state(s, val);
+	if (tep_get_field_val(s,  event, "prev_state_char", record, &val, 1) == 0)
+		trace_seq_putc(s, (char) val);
 
 	trace_seq_puts(s, " ==> ");
 
@@ -115,7 +94,7 @@ static int sched_switch_handler(struct trace_seq *s,
 	trace_seq_printf(s, "%lld", val);
 
 	if (tep_get_field_val(s, event, "next_prio", record, &val, 1) == 0)
-		trace_seq_printf(s, " [%d]", (int) val);
+		trace_seq_printf(s, " [%d]", (short) val);
 
 	return 0;
 }
-- 
2.40.1