linux-kernel - Re: [PATCH v5 1/2] sysctl: introduce new proc handler proc

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Date:   Thu, 5 Jan 2017 10:45:46 +0800
From:   hejianet <hejianet@...il.com>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     "J. Bruce Fields" <bfields@...ldses.org>,
        linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Serge Hallyn <serge@...lyn.com>,
        "David S. Miller" <davem@...emloft.net>,
        Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Kees Cook <keescook@...omium.org>,
        Hugh Dickins <hughd@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Daniel Cashman <dcashman@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jeff Layton <jlayton@...chiereds.net>,
        Trond Myklebust <trond.myklebust@...marydata.com>,
        Anna Schumaker <anna.schumaker@...app.com>
Subject: Re: [PATCH v5 1/2] sysctl: introduce new proc handler proc_dobool



On 05/01/2017 5:09 AM, J. Bruce Fields wrote:
> On Thu, Dec 15, 2016 at 03:24:20PM +0800, Jia He wrote:
>> This is to let bool variable could be correctly displayed in
>> big/little endian sysctl procfs. sizeof(bool) is arch dependent,
>> proc_dobool should work in all arches.
> Did Alexey Debriyan agree that this dealt with his objections?
Hi Alexey, any thoughts? ;-)
Thanks

B.R.
Jia
> Also it'd be nice to have a sign-off from somebody that's actually
> touched sysctl.c.  Then I could take it through the nfsd tree if that
> doesn't cause anyone trouble.
>
> --b.
>
>> Suggested-by: Pan Xinhui <xinhui@...ux.vnet.ibm.com>
>> Signed-off-by: Jia He <hejianet@...il.com>
>> ---
>>   include/linux/sysctl.h |  2 ++
>>   kernel/sysctl.c        | 41 +++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 43 insertions(+)
>>
>> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
>> index adf4e51..255a9c7 100644
>> --- a/include/linux/sysctl.h
>> +++ b/include/linux/sysctl.h
>> @@ -41,6 +41,8 @@ typedef int proc_handler (struct ctl_table *ctl, int write,
>>   
>>   extern int proc_dostring(struct ctl_table *, int,
>>   			 void __user *, size_t *, loff_t *);
>> +extern int proc_dobool(struct ctl_table *, int,
>> +			void __user *, size_t *, loff_t *);
>>   extern int proc_dointvec(struct ctl_table *, int,
>>   			 void __user *, size_t *, loff_t *);
>>   extern int proc_douintvec(struct ctl_table *, int,
>> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
>> index 706309f..c4bec65 100644
>> --- a/kernel/sysctl.c
>> +++ b/kernel/sysctl.c
>> @@ -2112,6 +2112,20 @@ static int proc_put_char(void __user **buf, size_t *size, char c)
>>   	return 0;
>>   }
>>   
>> +static int do_proc_dobool_conv(bool *negp, unsigned long *lvalp,
>> +				int *valp,
>> +				int write, void *data)
>> +{
>> +	if (write)
>> +		*(bool *)valp = *lvalp;
>> +	else {
>> +		int val = *(bool *)valp;
>> +
>> +		*lvalp = (unsigned long)val;
>> +	}
>> +	return 0;
>> +}
>> +
>>   static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
>>   				 int *valp,
>>   				 int write, void *data)
>> @@ -2258,6 +2272,26 @@ static int do_proc_dointvec(struct ctl_table *table, int write,
>>   }
>>   
>>   /**
>> + * proc_dobool - read/write a bool
>> + * @table: the sysctl table
>> + * @write: %TRUE if this is a write to the sysctl file
>> + * @buffer: the user buffer
>> + * @lenp: the size of the user buffer
>> + * @ppos: file position
>> + *
>> + * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
>> + * values from/to the user buffer, treated as an ASCII string.
>> + *
>> + * Returns 0 on success.
>> + */
>> +int proc_dobool(struct ctl_table *table, int write,
>> +		void __user *buffer, size_t *lenp, loff_t *ppos)
>> +{
>> +	return do_proc_dointvec(table, write, buffer, lenp, ppos,
>> +				do_proc_dobool_conv, NULL);
>> +}
>> +
>> +/**
>>    * proc_dointvec - read a vector of integers
>>    * @table: the sysctl table
>>    * @write: %TRUE if this is a write to the sysctl file
>> @@ -2885,6 +2919,12 @@ int proc_dostring(struct ctl_table *table, int write,
>>   	return -ENOSYS;
>>   }
>>   
>> +int proc_dobool(struct ctl_table *table, int write,
>> +                  void __user *buffer, size_t *lenp, loff_t *ppos)
>> +{
>> +        return -ENOSYS;
>> +}
>> +
>>   int proc_dointvec(struct ctl_table *table, int write,
>>   		  void __user *buffer, size_t *lenp, loff_t *ppos)
>>   {
>> @@ -2941,6 +2981,7 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write,
>>    * No sense putting this after each symbol definition, twice,
>>    * exception granted :-)
>>    */
>> +EXPORT_SYMBOL(proc_dobool);
>>   EXPORT_SYMBOL(proc_dointvec);
>>   EXPORT_SYMBOL(proc_douintvec);
>>   EXPORT_SYMBOL(proc_dointvec_jiffies);
>> -- 
>> 2.5.5