linux-kernel - Re: [PATCH v4] kselftests/damon: add support for cases where debugfs cannot be read

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Date:   Tue, 28 Jun 2022 09:07:11 +0530
From:   Gautam Menghani <gautammenghani201@...il.com>
To:     sj@...nel.org
Cc:     skhan@...uxfoundation.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] kselftests/damon: add support for cases where debugfs
 cannot be read

Cc'ing everyone as I forgot to group reply before. Also, I have included the 
example outputs in this reply.
On Tue, Jun 28, 2022 at 12:12:15AM +0530, Gautam Menghani wrote:
> On Mon, Jun 27, 2022 at 11:00:18AM -0600, Shuah Khan wrote:
> > On 6/25/22 2:03 PM, SeongJae Park wrote:
> > > Hi Gautam,
> > > 
> > > On Sun, 26 Jun 2022 01:22:45 +0530 Gautam <gautammenghani201@...il.com> wrote:
> > > 
> > > > The kernel is in lockdown mode when secureboot is enabled and hence
> > > > debugfs cannot be used. Add support for this and other general cases
> > > > where debugfs cannot be read and communicate the same to the user before
> > > > running tests.
> > > > 
> > > > Signed-off-by: Gautam <gautammenghani201@...il.com>
> > > 
> > > Reviewed-by: SeongJae Park <sj@...nel.org>
> > > 
> > > 
> > > Thanks,
> > > SJ
> > > 
> > > > ---
> > > > Changes in v2:
> > > > 1. Modify the error message to account for general cases.
> > > > 2. Change the return code so that the test is skipped.
> > > > 
> > > > Changes in v3:
> > > > 1. Change the name of variable holding the error message.
> > > > 
> > > > Changes in v4:
> > > > 1. Correct the mode of the source file.
> > > > 
> > > >   tools/testing/selftests/damon/_chk_dependency.sh | 10 ++++++++++
> > > >   1 file changed, 10 insertions(+)
> > > > 
> > > > diff --git a/tools/testing/selftests/damon/_chk_dependency.sh b/tools/testing/selftests/damon/_chk_dependency.sh
> > > > index 0189db81550b..0328ac0b5a5e 100644
> > > > --- a/tools/testing/selftests/damon/_chk_dependency.sh
> > > > +++ b/tools/testing/selftests/damon/_chk_dependency.sh
> > > > @@ -26,3 +26,13 @@ do
> > > >   		exit 1
> > > >   	fi
> > > >   done
> > > > +
> > > > +permission_error="Operation not permitted"
> > > > +for f in attrs target_ids monitor_on
> > > > +do
> > > > +	status=$( cat "$DBGFS/$f" 2>&1 )
> > > > +	if [ "${status#*$permission_error}" != "$status" ]; then
> > > > +		echo "Permission for reading $DBGFS/$f denied; maybe secureboot enabled?"
> > 
> > btw - does this run as a regular user or does it need root privilege?
> > If so add a test for that and skip with a message.
> 
> Yes this condition is reachable only with root user. If damon tests are run
> as regular user, the root check condition already skips the tests.
> 
> Tests output as regular user:
> +TAP version 13
> +1..6
> +# selftests: damon: debugfs_attrs.sh
> +# Run as root
> +ok 1 selftests: damon: debugfs_attrs.sh # SKIP
> +# selftests: damon: debugfs_schemes.sh
> +# Run as root
> 
> Tests output as root user:
> +TAP version 13
> +1..6
> +# selftests: damon: debugfs_attrs.sh
> +# Permission for reading /sys/kernel/debug/damon/attrs denied; maybe secureboot enabled?
> +ok 1 selftests: damon: debugfs_attrs.sh # SKIP
> +# selftests: damon: debugfs_schemes.sh
> +# Permission for reading /sys/kernel/debug/damon/attrs denied; maybe secureboot enabled?
> 
> Is any change needed in this patch?
> 
> > > > +		exit $ksft_skip
> > > > +	fi
> > > > +done
> > > > -- 
> > > > 2.36.1
> > > 
> > thanks,
> > -- Shuah