[LTP] [PATCH v3, 2/2] cgroup/cgroup_regression_test: Fix umount failure

[Petr Vorel <pvorel@suse.cz>]

> Hi Leo
> > The test sequence
> > 	mount -t cgroup -o<controllers>  <path>
> > 	mkdir<path>/<dir>
> > 	rmdir<path>/<dir>
> > 	umount<path>
> > 	mount -t cgroup -o<controllers>  <path>
> > would easily fail at the last mount with -EBUSY on certain platform.

> > The reason is that this test sequence would have the chance of
> > missing a release code path when doing rmdir and umount.

> > Adding a little delay between "rmdir" and "umount" could fix the problem,
> > so use tst_umount API instead of umount in "rmdir, umount" sequence.

> > Fixes: #839

> > Signed-off-by: Leo Yu-Chi Liang<ycliang@andestech.com>
> > ---
> >   .../controllers/cgroup/cgroup_regression_test.sh       | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)

> > diff --git a/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh b/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> > index 1f7f3820e..056166f11 100755
> > --- a/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> > +++ b/testcases/kernel/controllers/cgroup/cgroup_regression_test.sh
> > @@ -145,7 +145,7 @@ test2()
> >   	fi

> >   	rmdir cgroup/0 cgroup/1
> > -	umount cgroup/
> With adding a comment like
> # Avoid possible EBUSY error

> so when other converts this case into new api, they will keep to use 
> tst_umount.
+1

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

> Reviewed-by: Yang Xu <xuyang2018.jy@fujitsu.com>

> > +	tst_umount cgroup/
> >   }

> >   #---------------------------------------------------------------------------
> > @@ -193,7 +193,7 @@ test3()
> >   	wait $pid2 2>/dev/null

> >   	rmdir $cpu_subsys_path/0 2>  /dev/null
> > -	umount cgroup/ 2>  /dev/null
> > +	tst_umount cgroup/ 2>  /dev/null
> >   	check_kernel_bug
> >   }

> > @@ -222,7 +222,7 @@ test4()
> >   	mount -t cgroup -o none,name=foo cgroup cgroup/
> >   	mkdir cgroup/0
> >   	rmdir cgroup/0
> > -	umount cgroup/
> > +	tst_umount cgroup/
> here as well

> >   	if dmesg | grep -q "MAX_LOCKDEP_SUBCLASSES too low"; then
> >   		tst_res TFAIL "lockdep BUG was found"
> > @@ -254,7 +254,7 @@ test5()
> >   	mount -t cgroup none cgroup 2>  /dev/null
> >   	mkdir cgroup/0
> >   	rmdir cgroup/0
> > -	umount cgroup/ 2>  /dev/null
> > +	tst_umount cgroup/ 2>  /dev/null
> >   	check_kernel_bug
> >   }

> > @@ -290,7 +290,7 @@ test6()

> >   	mount -t cgroup -o ns xxx cgroup/>  /dev/null 2>&1
> >   	rmdir cgroup/[1-9]*>  /dev/null 2>&1
> > -	umount cgroup/
> > +	tst_umount cgroup/
> here as well
> >   	check_kernel_bug
> >   }