linux-ext4 - Re: [PATCH v2 5/5] common: exit -->

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Message-ID: <20250408143346.GD6274@frogsfrogsfrogs>
Date: Tue, 8 Apr 2025 07:33:46 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Zorro Lang <zlang@...hat.com>
Cc: "Nirjhar Roy (IBM)" <nirjhar.roy.lists@...il.com>,
	"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 v2 5/5] common: exit --> _exit

On Tue, Apr 08, 2025 at 10:27:48PM +0800, Zorro Lang wrote:
> On Tue, Apr 08, 2025 at 12:43:32AM +0530, Nirjhar Roy (IBM) wrote:
> > 
> > On 4/8/25 00:16, Ritesh Harjani (IBM) wrote:
> > > Zorro Lang <zlang@...hat.com> writes:
> > > 
> > > > On Fri, Apr 04, 2025 at 10:34:47AM +0530, Ritesh Harjani wrote:
> > > > > "Nirjhar Roy (IBM)" <nirjhar.roy.lists@...il.com> writes:
> > > > > 
> > > > > > Replace exit <return-val> with _exit <return-val> which
> > > > > > is introduced in the previous patch.
> > > > > > 
> > > > > > Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@...il.com>
> > > <...>
> > > > > > ---
> > > > > > @@ -225,7 +225,7 @@ _filter_bmap()
> > > > > >   die_now()
> > > > > >   {
> > > > > >   	status=1
> > > > > > -	exit
> > > > > > +	_exit
> > > > > Why not remove status=1 too and just do _exit 1 here too?
> > > > > Like how we have done at other places?
> > > > Yeah, nice catch! As the defination of _exit:
> > > > 
> > > >    _exit()
> > > >    {
> > > >         status="$1"
> > > >         exit "$status"
> > > >    }
> > > > 
> > > > The
> > > >    "
> > > >    status=1
> > > >    exit
> > > >    "
> > > > should be equal to:
> > > >    "
> > > >    _exit 1
> > > >    "
> > > > 
> > > > And "_exit" looks not make sense, due to it gives null to status.
> > > > 
> > > > Same problem likes below:
> > > > 
> > > > 
> > > > @@ -3776,7 +3773,7 @@ _get_os_name()
> > > >                  echo 'linux'
> > > >          else
> > > >                  echo Unknown operating system: `uname`
> > > > -               exit
> > > > +               _exit
> > > > 
> > > > 
> > > > The "_exit" without argument looks not make sense.
> > > > 
> > > That's right. _exit called with no argument could make status as null.
> > Yes, that is correct.
> > > To prevent such misuse in future, should we add a warning/echo message
> > 
> > Yeah, the other thing that we can do is 'status=${1:-0}'. In that case, for
>                                            ^^^^^^^^^^^^^^
> That's good to me, I'm just wondering if the default value should be "1", to
> tell us "hey, there's an unknown exit status" :)

I think status=1 usually means failure...

/usr/include/stdlib.h:92:#define        EXIT_FAILURE    1       /* Failing exit status.  */
/usr/include/stdlib.h:93:#define        EXIT_SUCCESS    0       /* Successful exit status.  */

--D

> Thanks,
> Zorro
> 
> > cases where the return value is a success, we simply use "_exit". Which one
> > do you think adds more value and flexibility to the usage?
> > 
> > --NR
> > 
> > > if the no. of arguments passed to _exit() is not 1?
> > > 
> > > -ritesh
> > 
> > -- 
> > Nirjhar Roy
> > Linux Kernel Developer
> > IBM, Bangalore
> > 
> 
>