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

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Date:   Fri, 3 Jun 2022 14:02:41 +0000
From:   Chuck Lever III <chuck.lever@...cle.com>
To:     Dongliang Mu <mudongliangabcd@...il.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 Jun 3, 2022, at 9:50 AM, Dongliang Mu <mudongliangabcd@...il.com> wrote:
> 
> 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,

Code inspection does suggest there could be a problem,
but I'm glad there isn't one. I can drop this one.


>>> 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

--
Chuck Lever