From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 26 Apr 2013 23:05:57 +0000 (-0600)
Subject: Ensure that stat outputs are serialized
X-Git-Tag: fio-2.1~8
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=cef9175e52e8a240117b9f45b228fdaa0f1c0572;hp=fdd5f15f8231e8c91c4deff22e630a34addd0fef

Ensure that stat outputs are serialized

Two issues:

- We don't want potentially two stat outputs running at the same time.
  This could potentially happen if USR1 or interval stats race with
  the thread exit.

- We could potentially crash if the interval or USR1 signaled stat
  output trigger when fio is tearing down. Let the main thread wait
  for any in-progress output in that case.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/backend.c b/backend.c
index 4d4e8efd..89ffee12 100644
--- a/backend.c
+++ b/backend.c
@@ -1895,6 +1895,7 @@ int fio_backend(void)
 		return 1;
 
 	set_genesis_time();
+	stat_init();
 	create_disk_util_thread();
 
 	cgroup_list = smalloc(sizeof(*cgroup_list));
@@ -1924,5 +1925,6 @@ int fio_backend(void)
 	fio_mutex_remove(startup_mutex);
 	fio_mutex_remove(writeout_mutex);
 	fio_mutex_remove(disk_thread_mutex);
+	stat_exit();
 	return exit_value;
 }
diff --git a/stat.c b/stat.c
index 03a45fc7..b3861887 100644
--- a/stat.c
+++ b/stat.c
@@ -14,6 +14,8 @@
 #include "lib/getrusage.h"
 #include "idletime.h"
 
+static struct fio_mutex *stat_mutex;
+
 void update_rusage_stat(struct thread_data *td)
 {
 	struct thread_stat *ts = &td->ts;
@@ -1141,7 +1143,7 @@ void init_thread_stat(struct thread_stat *ts)
 	ts->groupid = -1;
 }
 
-void show_run_stats(void)
+static void __show_run_stats(void)
 {
 	struct group_run_stats *runstats, *rs;
 	struct thread_data *td;
@@ -1359,6 +1361,13 @@ void show_run_stats(void)
 	free(threadstats);
 }
 
+void show_run_stats(void)
+{
+	fio_mutex_down(stat_mutex);
+	__show_run_stats();
+	fio_mutex_up(stat_mutex);
+}
+
 static void *__show_running_run_stats(void fio_unused *arg)
 {
 	struct thread_data *td;
@@ -1393,7 +1402,7 @@ static void *__show_running_run_stats(void fio_unused *arg)
 		td->update_rusage = 0;
 	}
 
-	show_run_stats();
+	__show_run_stats();
 
 	for_each_td(td, i) {
 		if (td_read(td) && td->io_bytes[DDIR_READ])
@@ -1405,6 +1414,7 @@ static void *__show_running_run_stats(void fio_unused *arg)
 	}
 
 	free(rt);
+	fio_mutex_up(stat_mutex);
 	return NULL;
 }
 
@@ -1417,8 +1427,14 @@ void show_running_run_stats(void)
 {
 	pthread_t thread;
 
-	pthread_create(&thread, NULL, __show_running_run_stats, NULL);
-	pthread_detach(thread);
+	fio_mutex_down(stat_mutex);
+
+	if (!pthread_create(&thread, NULL, __show_running_run_stats, NULL)) {
+		pthread_detach(thread);
+		return;
+	}
+
+	fio_mutex_up(stat_mutex);
 }
 
 static int status_interval_init;
@@ -1701,3 +1717,18 @@ void add_iops_sample(struct thread_data *td, enum fio_ddir ddir,
 
 	fio_gettime(&td->iops_sample_time, NULL);
 }
+
+void stat_init(void)
+{
+	stat_mutex = fio_mutex_init(FIO_MUTEX_UNLOCKED);
+}
+
+void stat_exit(void)
+{
+	/*
+	 * When we have the mutex, we know out-of-band access to it
+	 * have ended.
+	 */
+	fio_mutex_down(stat_mutex);
+	fio_mutex_remove(stat_mutex);
+}
diff --git a/stat.h b/stat.h
index b1bf5dc3..541b77e4 100644
--- a/stat.h
+++ b/stat.h
@@ -199,6 +199,9 @@ struct jobs_eta {
 	uint8_t run_str[];
 };
 
+extern void stat_init(void);
+extern void stat_exit(void);
+
 extern void show_thread_status(struct thread_stat *ts, struct group_run_stats *rs);
 extern void show_group_stats(struct group_run_stats *rs);
 extern int calc_thread_status(struct jobs_eta *je, int force);