linux-kernel - Re: [PATCH] nfsd: make destory function more elegant

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Message-ID: <CAD-N9QUAvTZMFz6A+=NxvyHaO102mrc7+5gL4K9xV5j3AEuvjQ@mail.gmail.com>
Date:   Fri, 3 Jun 2022 21:50:44 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Chuck Lever III <chuck.lever@...cle.com>
Cc:     Dongliang Mu <dzm91@...t.edu.cn>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] nfsd: make destory function more elegant

On Thu, Jun 2, 2022 at 10:30 PM Chuck Lever III <chuck.lever@...cle.com> wrote:
>
>
>
> > On Jun 2, 2022, at 1:56 AM, Dongliang Mu <dzm91@...t.edu.cn> wrote:
> >
> > From: Dongliang Mu <mudongliangabcd@...il.com>
> >
> > In init_nfsd, the undo operation of create_proc_exports_entry is:
> >
> >        remove_proc_entry("fs/nfs/exports", NULL);
> >        remove_proc_entry("fs/nfs", NULL);
> >
> > This may lead to maintaince issue. Declare the undo function
>
> "maintenance"

Sorry for the typo.

>
>
> > destroy_proc_exports_entry based on CONFIG_PROC_FS
>
> IIUC, the issue is that if CONFIG_PROC_FS is not set,
> fs/nfsd/nfsctl.c fails to compile?

The answer is no. There is no bug in the code.

At first, I thought this might cause the miscompilation or bug. But
actually the code is fine.

Because remove_proc_entry is defined as an empty function if
CONFIG_PROC_FS is not set,

>
>
> > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
> > ---
> > fs/nfsd/nfsctl.c | 16 ++++++++++++----
> > 1 file changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index 0621c2faf242..83b34ccbef5a 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -1450,11 +1450,21 @@ static int create_proc_exports_entry(void)
> >       }
> >       return 0;
> > }
> > +
> > +static void destroy_proc_exports_entry(void)
> > +{
> > +     remove_proc_entry("fs/nfs/exports", NULL);
> > +     remove_proc_entry("fs/nfs", NULL);
> > +}
> > #else /* CONFIG_PROC_FS */
> > static int create_proc_exports_entry(void)
> > {
> >       return 0;
> > }
> > +
> > +static void destroy_proc_exports_entry(void)
> > +{
> > +}
> > #endif
> >
> > unsigned int nfsd_net_id;
> > @@ -1555,8 +1565,7 @@ static int __init init_nfsd(void)
> > out_free_subsys:
> >       unregister_pernet_subsys(&nfsd_net_ops);
> > out_free_exports:
> > -     remove_proc_entry("fs/nfs/exports", NULL);
> > -     remove_proc_entry("fs/nfs", NULL);
> > +     destroy_proc_exports_entry();
> > out_free_lockd:
> >       nfsd_lockd_shutdown();
> >       nfsd_drc_slab_free();
> > @@ -1576,8 +1585,7 @@ static void __exit exit_nfsd(void)
> >       unregister_cld_notifier();
> >       unregister_pernet_subsys(&nfsd_net_ops);
> >       nfsd_drc_slab_free();
> > -     remove_proc_entry("fs/nfs/exports", NULL);
> > -     remove_proc_entry("fs/nfs", NULL);
> > +     destroy_proc_exports_entry();
> >       nfsd_stat_shutdown();
> >       nfsd_lockd_shutdown();
> >       nfsd4_free_slabs();
> > --
> > 2.25.1
> >
>
> --
> Chuck Lever
>
>
>