From: Bart Van Assche <bvanassche@acm.org>
Date: Sat, 13 Jun 2020 18:33:37 +0000 (-0700)
Subject: Enable error checking for the mutex that serializes overlapping I/O
X-Git-Tag: fio-3.21~15^2~1
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=a38c70a8b84f6f000bd15bec694a4f8b278d46a3;p=fio.git

Enable error checking for the mutex that serializes overlapping I/O

Since it is nontrivial to verify that pthread_mutex_lock() and unlock
calls are paired for the overlap_check mutex, enable runtime verification.
The PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP initializer causes
pthread_mutex_lock() to fail with EDEADLK if the mutex was already locked
and causes pthread_mutex_unlock() to fail with EPERM if the mutex is owned
by another thread.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---

diff --git a/backend.c b/backend.c
index 0075a733..0e454cdd 100644
--- a/backend.c
+++ b/backend.c
@@ -66,7 +66,11 @@ unsigned int stat_number = 0;
 int shm_id = 0;
 int temp_stall_ts;
 unsigned long done_secs = 0;
+#ifdef PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
+pthread_mutex_t overlap_check = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP;
+#else
 pthread_mutex_t overlap_check = PTHREAD_MUTEX_INITIALIZER;
+#endif
 
 #define JOB_START_TIMEOUT	(5 * 1000)
 
@@ -1535,7 +1539,7 @@ static void *thread_main(void *data)
 	uint64_t bytes_done[DDIR_RWDIR_CNT];
 	int deadlock_loop_cnt;
 	bool clear_state;
-	int ret;
+	int res, ret;
 
 	sk_out_assign(sk_out);
 	free(fd);
@@ -1860,11 +1864,15 @@ static void *thread_main(void *data)
 	 * offload mode so that we don't clean up this job while
 	 * another thread is checking its io_u's for overlap
 	 */
-	if (td_offload_overlap(td))
-		pthread_mutex_lock(&overlap_check);
+	if (td_offload_overlap(td)) {
+		int res = pthread_mutex_lock(&overlap_check);
+		assert(res == 0);
+	}
 	td_set_runstate(td, TD_FINISHING);
-	if (td_offload_overlap(td))
-		pthread_mutex_unlock(&overlap_check);
+	if (td_offload_overlap(td)) {
+		res = pthread_mutex_unlock(&overlap_check);
+		assert(res == 0);
+	}
 
 	update_rusage_stat(td);
 	td->ts.total_run_time = mtime_since_now(&td->epoch);
diff --git a/ioengines.c b/ioengines.c
index c1b430a1..1c5970a4 100644
--- a/ioengines.c
+++ b/ioengines.c
@@ -313,8 +313,10 @@ enum fio_q_status td_io_queue(struct thread_data *td, struct io_u *io_u)
 	 * started the overlap check because the IO_U_F_FLIGHT
 	 * flag is now set
 	 */
-	if (td_offload_overlap(td))
-		pthread_mutex_unlock(&overlap_check);
+	if (td_offload_overlap(td)) {
+		int res = pthread_mutex_unlock(&overlap_check);
+		assert(res == 0);
+	}
 
 	assert(fio_file_open(io_u->file));
 
diff --git a/rate-submit.c b/rate-submit.c
index 3bcb5053..b7b70372 100644
--- a/rate-submit.c
+++ b/rate-submit.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2015 Jens Axboe <axboe@kernel.dk>
  *
  */
+#include <assert.h>
 #include "fio.h"
 #include "ioengines.h"
 #include "lib/getrusage.h"
@@ -11,7 +12,7 @@
 
 static void check_overlap(struct io_u *io_u)
 {
-	int i;
+	int i, res;
 	struct thread_data *td;
 
 	/*
@@ -26,7 +27,8 @@ static void check_overlap(struct io_u *io_u)
 	 * IO_U_F_FLIGHT flag is set so that this io_u can be checked by other
 	 * threads as they assess overlap.
 	 */
-	pthread_mutex_lock(&overlap_check);
+	res = pthread_mutex_lock(&overlap_check);
+	assert(res == 0);
 
 retry:
 	for_each_td(td, i) {
@@ -39,8 +41,10 @@ retry:
 		if (!in_flight_overlap(&td->io_u_all, io_u))
 			continue;
 
-		pthread_mutex_unlock(&overlap_check);
-		pthread_mutex_lock(&overlap_check);
+		res = pthread_mutex_unlock(&overlap_check);
+		assert(res == 0);
+		res = pthread_mutex_lock(&overlap_check);
+		assert(res == 0);
 		goto retry;
 	}
 }