t_ofd_locks: fix sem initialization sequence

The locker was waiting for sem_otime on sem0 to became non-zero after
incrementing sem0 himself. So sem_otime was never 0 at the time of
checking it, so the check was redundant/wrong.

This patch:
- moves the increment of sem1 to the lock-tester site
- lock-setter waits for that sem1 event, for which this patch replaces
  the wait loop on sem_otime with GETVAL loop, adding a small sleep
- increment of sem0 to 2 moved past that sem1 event. That sem0 event
  is currently not used/waited.

This guarantees that the lock-setter is working only after lock-getter
is fully initialized.

CC: fstests@vger.kernel.org
CC: Murphy Zhou <xzhou@redhat.com>
CC: Jeff Layton <jlayton@kernel.org>
CC: Zorro Lang <zlang@redhat.com>

Signed-off-by: Stas Sergeev <stsp2@yandex.ru>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>

1 files changed, 25 insertions, 19 deletions

diff --git a/src/t_ofd_locks.c b/src/t_ofd_locks.c
index 88ef2690b8..58cb095999 100644
--- a/src/t_ofd_locks.c
+++ b/src/t_ofd_locks.c
@@ -294,32 +294,29 @@ int main(int argc, char **argv)
 		semu.array = vals;
 		if (semctl(semid, 2, SETALL, semu) == -1)
 			err_exit("init sem", errno);
-		/* Inc both new sem to 2 */
-		sop.sem_num = 0;
-		sop.sem_op = 1;
-		sop.sem_flg = 0;
-		ts.tv_sec = 5;
-		ts.tv_nsec = 0;
-		if (semtimedop(semid, &sop, 1, &ts) == -1)
-			err_exit("inc sem0 2", errno);
-		sop.sem_num = 1;
-		sop.sem_op = 1;
-		sop.sem_flg = 0;
-		ts.tv_sec = 5;
-		ts.tv_nsec = 0;
-		if (semtimedop(semid, &sop, 1, &ts) == -1)
-			err_exit("inc sem1 2", errno);
 
 		/*
-		 * Wait initialization complete. semctl(2) only update
-		 * sem_ctime, semop(2) will update sem_otime.
+		 * Wait initialization complete.
 		 */
 		ret = -1;
 		do {
+			if (ret != -1)
+				usleep(100000);
 			memset(&sem_ds, 0, sizeof(sem_ds));
 			semu.buf = &sem_ds;
-			ret = semctl(semid, 0, IPC_STAT, semu);
-		} while (!(ret == 0 && sem_ds.sem_otime != 0));
+			ret = semctl(semid, 1, GETVAL, semu);
+			if (ret == -1)
+				err_exit("wait sem1 2", errno);
+		} while (ret != 2);
+
+		/* Inc sem0 to 2 */
+		sop.sem_num = 0;
+		sop.sem_op = 1;
+		sop.sem_flg = 0;
+		ts.tv_sec = 5;
+		ts.tv_nsec = 0;
+		if (semtimedop(semid, &sop, 1, &ts) == -1)
+			err_exit("inc sem0 2", errno);
 
 		/* place the lock */
 		if (fcntl(fd, setlk_macro, &flk) < 0)
@@ -385,6 +382,15 @@ int main(int argc, char **argv)
 				err_exit("wait sem1 1", errno);
 		} while (ret != 1);
 
+		/* inc sem1 to 2 (initialization completed) */
+		sop.sem_num = 1;
+		sop.sem_op = 1;
+		sop.sem_flg = 0;
+		ts.tv_sec = 5;
+		ts.tv_nsec = 0;
+		if (semtimedop(semid, &sop, 1, &ts) == -1)
+			err_exit("inc sem1 2", errno);
+
 		/* wait sem0 == 0 (setlk and close fd done) */
 		sop.sem_num = 0;
 		sop.sem_op = 0;