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

[Xiao Yang <yangx.jy@cn.fujitsu.com>]

On 2018/10/22 15:29, Xiao Yang wrote:
> 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).
Hi,

Sorry, the RHEL version is sensltive, so please remove it when pushing
the patch.

Best Regards,
Xiao Yang
> 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);