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Segmentation fault occurs with --calibrate

Powertop New Lekensteyn 2 participants 2 messages May 17, 2012

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Lekensteyn

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#0 lore raw

Hi,

With the new Powertop 2.0, powertop --calibrate segfaults. Debugging output is attached:

Quoted 16 lines

Starting program: /tmp/powertop-2.0/src/powertop --calibrate [Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Starting PowerTOP power estimate calibration
Calibrating idle

Program received signal SIGSEGV, Segmentation fault. perf_bundle::start (this=0x0) at perf/perf_bundle.cpp:180
180 for (i = 0; i < events.size(); i++) {
(gdb) bt

#0  perf_bundle::start (this=0x0) at perf/perf_bundle.cpp:180
#1  0x000000000040f9b0 in start_cpu_measurement () at cpu/cpu.cpp:297
#2  0x0000000000442655 in one_measurement (seconds=15) at main.cpp:182
#3  0x000000000043f4c2 in idle_calibration () at calibrate/calibrate.cpp:423
#4  calibrate () at calibrate/calibrate.cpp:466
#5  0x000000000040665f in main (argc=2, argv=0x7fffffffe718) at main.cpp:325
Quoted 5 lines

(gdb) up
#1 0x000000000040f9b0 in start_cpu_measurement () at cpu/cpu.cpp:297
297 perf_events->start()
(gdb) print perf_events
$5 = (perf_bundle *) 0x0

The order of processing seems flawed. Immediately during argument processing, calibrate() is called. But start_cpu_measurement requires some initialization which is done by enumerate_cpus() in the main() function after arguments processing. You know your code better, so I'll gratefully wait for your patches.

Thanks,
Peter

#1 lore raw

PATCH 1/1 factor out powertop_init() function [was "Segmentation fault occurs with --calibrate"]

[PATCH] factor out powertop_init() function

Factor out powertop_init() function to perform basic initialization on powertop start up.

Commit 057d6126eb6329c86b29a2e0219c0d0e49a84191 moved init after commandline options parsing. However, in some cases we need it before parsing, e.g. -- calibration.

Reported-by Lekensteyn <lekensteyn(a)gmail.com>
Signed-off-by Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com>

---

 src/main.cpp |  110 +++++++++++++++++++++++++++++++---------------------------
 1 file changed, 58 insertions(+), 52 deletions(-)
src/main.cpp +58 -52
index 433fea6..b5720f0 100644
@@ -280,15 +280,68 @@ static void checkroot() {
 	}
 	
 }
-int main(int argc, char **argv)
+
+static void powertop_init(void)
 {
+	static char initialized = 0;
 	int ret;
+	struct statfs st_fs;
+
+	if (initialized)
+		return;
+
+	checkroot(); 
+	ret = system("/sbin/modprobe cpufreq_stats > /dev/null 2>&1");
+	ret = system("/sbin/modprobe msr > /dev/null 2>&1");
+	statfs("/sys/kernel/debug", &st_fs);
+
+	if (st_fs.f_type != (long) DEBUGFS_MAGIC) {
+		if (access("/bin/mount", X_OK) == 0) {
+			ret = system("/bin/mount -t debugfs debugfs /sys/kernel/debug > /dev/null 2>&1");
+		} else {
+			ret = system("mount -t debugfs debugfs /sys/kernel/debug > /dev/null 2>&1");
+		}
+		if (ret != 0) {
+			printf(_("Failed to mount debugfs!\n"));
+			printf(_("exiting...\n"));
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	srand(time(NULL));
+
+	if (access("/var/cache/", W_OK) == 0)
+		mkdir("/var/cache/powertop", 0600);
+	else
+		mkdir("/data/local/powertop", 0600);
+
+	load_results("saved_results.powertop");
+	load_parameters("saved_parameters.powertop");
+
+	enumerate_cpus();
+	create_all_devices();
+	detect_power_meters();
+
+	register_parameter("base power", 100, 0.5);
+	register_parameter("cpu-wakeups", 39.5);
+	register_parameter("cpu-consumption", 1.56);
+	register_parameter("gpu-operations", 0.5576);
+	register_parameter("disk-operations-hard", 0.2);
+	register_parameter("disk-operations", 0.0);
+	register_parameter("xwakes", 0.1);
+
+	load_board_params();
+	initialized = 1;
+}
+
+
+int main(int argc, char **argv)
+{
 	int option_index;
 	int c;
 	bool wantreport = FALSE;
 	char filename[4096];
 	int  iterations = 1;
-	struct statfs st_fs;
 
 #ifndef DISABLE_TRYCATCH
 	set_new_handler(out_of_memory);

@@ -322,6 +375,7 @@ int main(int argc, char **argv)
 				break;
 
 			case 'c':
+				powertop_init();
 				calibrate();
 				break;
 

@@ -350,48 +404,8 @@ int main(int argc, char **argv)
 				break;
 		}
 	}
-	
-	checkroot(); 
-	ret = system("/sbin/modprobe cpufreq_stats > /dev/null 2>&1");
-	ret = system("/sbin/modprobe msr > /dev/null 2>&1");
-
-	statfs("/sys/kernel/debug", &st_fs);
-	if (st_fs.f_type != (long) DEBUGFS_MAGIC) {
-		if (access("/bin/mount", X_OK) == 0) {
-			ret = system("/bin/mount -t debugfs debugfs /sys/kernel/debug > /dev/null 2>&1");
-		} else {
-			ret = system("mount -t debugfs debugfs /sys/kernel/debug > /dev/null 2>&1");
-		}
-		if (ret != 0) {
-			printf(_("Failed to mount debugfs!\n"));
-			printf(_("exiting...\n"));
-			exit(EXIT_FAILURE);
-		}
-	}
-
-	srand(time(NULL));
-
-	if (access("/var/cache/", W_OK) == 0)
-		mkdir("/var/cache/powertop", 0600);
-	else
-		mkdir("/data/local/powertop", 0600);
 
-	load_results("saved_results.powertop");
-	load_parameters("saved_parameters.powertop");
-
-	enumerate_cpus();
-	create_all_devices();
-	detect_power_meters();
-
-	register_parameter("base power", 100, 0.5);
-	register_parameter("cpu-wakeups", 39.5);
-	register_parameter("cpu-consumption", 1.56);
-	register_parameter("gpu-operations", 0.5576);
-	register_parameter("disk-operations-hard", 0.2);
-	register_parameter("disk-operations", 0.0);
-	register_parameter("xwakes", 0.1);
-
-	load_board_params();
+	powertop_init();
 
 	if (wantreport)
 		 report(time_out, iterations, filename);

@@ -399,8 +413,6 @@ int main(int argc, char **argv)
 	if (debug_learning)
 		printf("Learning debugging enabled\n");
 
-
-
 	learn_parameters(250, 0);
 	save_parameters("saved_parameters.powertop");
 

@@ -412,7 +424,6 @@ int main(int argc, char **argv)
 		exit(0);
 	}
 
-
 	/* first one is short to not let the user wait too long */
 	init_display();
 	one_measurement(1);

@@ -420,11 +431,9 @@ int main(int argc, char **argv)
 	tuning_update_display();
 	show_tab(0);
 
-
-
 	while (!leave_powertop) {
-		one_measurement(time_out);
 		show_cur_tab();
+		one_measurement(time_out);
 		learn_parameters(15, 0);
 	}
 #ifndef DISABLE_NCURSES

@@ -432,7 +441,6 @@ int main(int argc, char **argv)
 #endif
 	printf(_("Leaving PowerTOP\n"));
 
-
 	end_process_data();
 	clear_process_data();
 	end_cpu_data();

@@ -450,6 +458,4 @@ int main(int argc, char **argv)
 	clear_all_cpus();
 
 	return 0;
-
-
 }