idlestat: Fix recording of initial and final P-states

The initial and final pstates were stored only if the display
options at the time of creating the trace file included display
of P-states. Since the trace may later be imported with the
P-state display on, add the pseudo P-state changes to the trace
unconditionally.

In addition, the return value of get_trace_ts was never checked
for error. The error checking has been added. Since floating
point comparison for equality is unreliable, the function now
returns only status and the actual data is relayed by modifying
memory pointed to by a function parameter. Error messages have
been added to the get_trace_ts function.

Signed-off-by: Tuukka Tikkanen <tuukka.tikkanen@linaro.org>

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>

1 files changed, 20 insertions, 13 deletions

diff --git a/idlestat.c b/idlestat.c
index 01827ef..5d9f12e 100644
--- a/idlestat.c
+++ b/idlestat.c
@@ -93,25 +93,32 @@ static inline void *ptrerror(const char *str)
 
 #define TRACE_TS_FORMAT "%*[^:]:%lf"
 
-static double get_trace_ts(void)
+static int get_trace_ts(double *ts)
 {
 	FILE *f;
-	double ts;
 
 	f = fopen(TRACE_STAT_FILE, "r");
 	if (!f)
-		return -1;
+		return error("fopen " TRACE_STAT_FILE);
 
 	while (fgets(buffer, BUFSIZE, f)) {
 		if (!strstr(buffer, "now ts"))
 			continue;
-		if (!sscanf(buffer, TRACE_TS_FORMAT, &ts))
-			ts = -1;
-		break;
+
+		fclose(f);
+
+		if (sscanf(buffer, TRACE_TS_FORMAT, ts) == 1)
+			return 0;
+
+		fprintf(stderr, "get_trace_ts: Failed to parse timestamp\n");
+		return -1;
 	}
+
 	fclose(f);
 
-	return ts;
+	fprintf(stderr, "get_trace_ts: Failed to find timestamp in %s\n",
+		TRACE_STAT_FILE);
+	return -1;
 }
 
 static int display_cstates(struct report_ops *ops, void *arg, char *cpu, void *report_data)
@@ -1607,10 +1614,10 @@ int main(int argc, char *argv[], char *const envp[])
 			return 1;
 
 		/* Get starting timestamp */
-		if (options.display & FREQUENCY_DISPLAY) {
-			start_ts = get_trace_ts();
-			initp = build_init_pstates();
-		}
+		if (get_trace_ts(&start_ts) == -1)
+			return 1;
+
+		initp = build_init_pstates();
 
 		/* Start the recording */
 		if (idlestat_trace_enable(true))
@@ -1635,8 +1642,8 @@ int main(int argc, char *argv[], char *const envp[])
 			return 1;
 
 		/* Get ending timestamp */
-		if (options.display & FREQUENCY_DISPLAY)
-			end_ts = get_trace_ts();
+		if (get_trace_ts(&end_ts) == -1)
+			return 1;
 
 		/* At this point we should have some spurious wake up
 		 * at the beginning of the traces and at the end (wake