[LTP] [PATCH] tbio/ltp_tbio.c: Change the order of calling blk_cleanup_queue() and del_gendisk()

[Xiao Yang]

Removing ltp_tbio.ko module always reproduced a warning and panic
on the old kernels that have backported kernel commit a063057d7c73
(e.g. RHEL7.6).

Removing ltp_tbio.ko module calls blk_cleanup_queue() and del_gendisk()
in the order so that it triggers races or warnings since commit a063057d7c73
in kernel, and some kernel modules have fixed the issue, as below:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=57678e5a3d5145e5f08aa1d307ba219b27b1765a
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0fa8ebdd4244b8e652cc5341c3d5b4b06f84a637
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d8115c35bf3ee575cfc9c51ac9853f58a21a43dc
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=392db38058eb47250a9d0cc737af37e78a7e443d

We also try to fix the issue in the same way.

Note:
A lot of structs and functions in ltp_tbio.ko module based on old
kernel(e.g. 3.10.0) has been changed on upstream kernel, so ltp_tbio.ko
module cannot be built on upstream kernel.  Perhaps ltp_tbio.ko
module needs to be updated, but we want to fix the issue first.

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
---
 testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c b/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
index 48cc588..0a9cd40 100644
--- a/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
+++ b/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
@@ -562,8 +562,8 @@ module_init(tbio_init);
 
 static void tbio_exit(void)
 {
-	blk_cleanup_queue(tbio_dev.q);
 	del_gendisk(tbio_dev.gd);
+	blk_cleanup_queue(tbio_dev.q);
 	put_disk(tbio_dev.gd);
 	unregister_blkdev(TBIO_MAJOR, DEVICE_NAME);
 	vfree(tbio_dev.data);
-- 
1.8.3.1