linux-ext4 - Re: [PATCH v3 5/6] common/config: Introduce

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Message-ID: <1b923260-2879-40d1-8543-15272a296ca6@gmail.com>
Date: Tue, 8 Apr 2025 22:05:30 +0530
From: "Nirjhar Roy (IBM)" <nirjhar.roy.lists@...il.com>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>, fstests@...r.kernel.org,
 linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
 ojaswin@...ux.ibm.com, zlang@...nel.org, david@...morbit.com
Subject: Re: [PATCH v3 5/6] common/config: Introduce _exit wrapper around exit
 command


On 4/8/25 22:02, Darrick J. Wong wrote:
> On Tue, Apr 08, 2025 at 09:45:53PM +0530, Nirjhar Roy (IBM) wrote:
>> On 4/8/25 14:43, Ritesh Harjani (IBM) wrote:
>>> "Nirjhar Roy (IBM)" <nirjhar.roy.lists@...il.com> writes:
>>>
>>>> We should always set the value of status correctly when we are exiting.
>>>> Else, "$?" might not give us the correct value.
>>>> If we see the following trap
>>>> handler registration in the check script:
>>>>
>>>> if $OPTIONS_HAVE_SECTIONS; then
>>>>        trap "_kill_seq; _summary; exit \$status" 0 1 2 3 15
>>>> else
>>>>        trap "_kill_seq; _wrapup; exit \$status" 0 1 2 3 15
>>>> fi
>>>>
>>>> So, "exit 1" will exit the check script without setting the correct
>>>> return value. I ran with the following local.config file:
>>>>
>>>> [xfs_4k_valid]
>>>> FSTYP=xfs
>>>> TEST_DEV=/dev/loop0
>>>> TEST_DIR=/mnt1/test
>>>> SCRATCH_DEV=/dev/loop1
>>>> SCRATCH_MNT=/mnt1/scratch
>>>>
>>>> [xfs_4k_invalid]
>>>> FSTYP=xfs
>>>> TEST_DEV=/dev/loop0
>>>> TEST_DIR=/mnt1/invalid_dir
>>>> SCRATCH_DEV=/dev/loop1
>>>> SCRATCH_MNT=/mnt1/scratch
>>>>
>>>> This caused the init_rc() to catch the case of invalid _test_mount
>>>> options. Although the check script correctly failed during the execution
>>>> of the "xfs_4k_invalid" section, the return value was 0, i.e "echo $?"
>>>> returned 0. This is because init_rc exits with "exit 1" without
>>>> correctly setting the value of "status". IMO, the correct behavior
>>>> should have been that "$?" should have been non-zero.
>>>>
>>>> The next patch will replace exit with _exit.
>>>>
>>>> Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@...il.com>
>>>> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
>>>> Reviewed-by: Dave Chinner <dchinner@...hat.com>
>>>> ---
>>>>    common/config | 8 ++++++++
>>>>    1 file changed, 8 insertions(+)
>>>>
>>>> diff --git a/common/config b/common/config
>>>> index 79bec87f..eb6af35a 100644
>>>> --- a/common/config
>>>> +++ b/common/config
>>>> @@ -96,6 +96,14 @@ export LOCAL_CONFIGURE_OPTIONS=${LOCAL_CONFIGURE_OPTIONS:=--enable-readline=yes}
>>>>    export RECREATE_TEST_DEV=${RECREATE_TEST_DEV:=false}
>>>> +# This functions sets the exit code to status and then exits. Don't use
>>>> +# exit directly, as it might not set the value of "status" correctly.
>>> ...as it might not set the value of "$status" correctly, which is used
>>> as an exit code in the trap handler routine set up by the check script.
>>>
>>>> +_exit()
>>>> +{
>>>> +	status="$1"
>>>> +	exit "$status"
>>>> +}
>>>> +
>>> I agree with Darrick’s suggestion here. It’s safer to update status only
>>> when an argument is passed - otherwise, it’s easy to trip over this.
>>>
>>> Let’s also avoid defaulting status to 0 inside _exit(). That way, if the
>>> caller forgets to pass an argument but has explicitly set status
>>> earlier, we preserve the intended value.
>>>
>>> We should update _exit() with...
>>>
>>> test -n "$1" && status="$1"
>> Okay, so in that case if someone does "status=<value>;_exit", we should end
>> up with the "<value>" instead of something else, right?
> Right.  I think.  AFAICT the following simple program actually does
> return 5 despite the cleanup:
>
> trap 'echo cleanup' INT QUIT TERM EXIT
> exit 5
>
> But since fstests set a variable named "status" and then "exit $status"
> from cleanup, I think it doesn't matter how status gets set as long as
> it /does/ get set somewhere.

Right, I have got the idea. I will make the changes in next revision.

--NR

>
> --D
>
>> --NR
>>
>>> -ritesh
>>>
>>>
>>>>    # Handle mkfs.$fstyp which does (or does not) require -f to overwrite
>>>>    set_mkfs_prog_path_with_opts()
>>>>    {
>>>> -- 
>>>> 2.34.1
>> -- 
>> Nirjhar Roy
>> Linux Kernel Developer
>> IBM, Bangalore
>>
-- 
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore