correct and simplify hrtimer plugin

The current hrtimer plugin code is broken wrt.
the return values, but it can now ignore the
trace_seq_* return values completely and focus
on parsing the data. Also, the handler API
should return 0 (all OK) or negative numbers
on errors.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

1 files changed, 26 insertions, 33 deletions

diff --git a/plugin_hrtimer.c b/plugin_hrtimer.c
index 9d9b969..2a074e7 100644
--- a/plugin_hrtimer.c
+++ b/plugin_hrtimer.c
@@ -4,6 +4,7 @@
 
 #include "parse-events.h"
 
+/* return -1 (field not found/not valid number), 0 (ok), 1 (buffer full) */
 static int _print_field(struct trace_seq *s, const char *fmt,
                         struct event *event, const char *name, const void *data)
 {
@@ -11,78 +12,70 @@ static int _print_field(struct trace_seq *s, const char *fmt,
         unsigned long long val;
 
         if (!f)
-                return 0;
+                return -1;
 
         if (pevent_read_number_field(f, data, &val))
-                return 0;
+                return -1;
 
         return trace_seq_printf(s, fmt, val);
 }
 
-static int print_field(struct trace_seq *s, const char *fmt,
-                       struct event *event, const char *name, const void *data)
+/* return 0 (ok), 1 (buffer full) */
+static void print_field(struct trace_seq *s, const char *fmt,
+                        struct event *event, const char *name, const void *data)
 {
         int ret = _print_field(s, fmt, event, name, data);
 
-        if (ret == 0)
-                ret = trace_seq_printf(s, "CAN'T FIND FIELD \"%s\"", name);
-
-        return ret;
+        if (ret == -1)
+                trace_seq_printf(s, "CAN'T FIND FIELD \"%s\"", name);
 }
 
 static int timer_expire_handler(struct trace_seq *s, void *data, int size,
                                 struct event *event)
 {
-        int ret = 0, tmp;
+        trace_seq_printf(s, "hrtimer=");
 
-        ret += trace_seq_printf(s, "hrtimer=");
-        tmp = _print_field(s, "0x%llx", event, "timer", data);
-        if (tmp)
-                ret += tmp;
-        else
-                ret += print_field(s, "0x%llx", event, "hrtimer", data);
+        if (_print_field(s, "0x%llx", event, "timer", data) == -1)
+                print_field(s, "0x%llx", event, "hrtimer", data);
 
-        ret += trace_seq_printf(s, " now=");
+        trace_seq_printf(s, " now=");
 
-        ret += print_field(s, "%llu", event, "now", data);
+        print_field(s, "%llu", event, "now", data);
 
-        return ret;
+        return 0;
 }
 
 static int timer_start_handler(struct trace_seq *s, void *data, int size,
                                struct event *event)
 {
         struct format_field *fn = pevent_find_field(event, "function");
-        int ret = 0, tmp;
 
-        ret += trace_seq_printf(s, "hrtimer=");
-        tmp = _print_field(s, "0x%llx", event, "timer", data);
-        if (tmp)
-                ret += tmp;
-        else
-                ret += print_field(s, "0x%llx", event, "hrtimer", data);
+        trace_seq_printf(s, "hrtimer=");
+
+        if (_print_field(s, "0x%llx", event, "timer", data) == -1)
+                print_field(s, "0x%llx", event, "hrtimer", data);
 
         if (!fn) {
-                ret += trace_seq_printf(s, " function=MISSING");
+                trace_seq_printf(s, " function=MISSING");
         } else {
                 unsigned long long function;
                 const char *func;
 
                 if (pevent_read_number_field(fn, data, &function))
-                        ret += trace_seq_printf(s, " function=INVALID");
+                        trace_seq_printf(s, " function=INVALID");
 
                 func = pevent_find_function(function);
 
-                ret += trace_seq_printf(s, " function=%s", func);
+                trace_seq_printf(s, " function=%s", func);
         }
 
-        ret += trace_seq_printf(s, " expires=");
-        ret += print_field(s, "%llu", event, "expires", data);
+        trace_seq_printf(s, " expires=");
+        print_field(s, "%llu", event, "expires", data);
 
-        ret += trace_seq_printf(s, " softexpires=");
-        ret += print_field(s, "%llu", event, "softexpires", data);
+        trace_seq_printf(s, " softexpires=");
+        print_field(s, "%llu", event, "softexpires", data);
 
-        return ret;
+        return 0;
 }
 
 int PEVENT_PLUGIN_LOADER(void)