[PATCH v5 0/2] change the proc handler for nsm_use_hostnames

[PATCH v5 0/2] change the proc handler for nsm_use_hostnames

[Jia He]

nsm_use_hostnames is a module parameter and it will be exported to sysctl
procfs. This is to let user sometimes change it from userspace. But the
minimal unit for sysctl procfs read/write it sizeof(int).
In big endian system, the converting from/to  bool to/from int will cause
error for proc items.

This patch introduces a new proc handler proc_dobool for nsm_use_hostnames.

Changes:
v5: Fix compilation error when CONFIG_PROC_SYSCTL is not set 
v4: Change (u8 *) to (bool *)
v3: Introduce a new proc handler proc_dou8vec(suggested by Xinhui Pan)
v2: Change extern type in lockd.h

The test case I used:
/***************************************************************/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sysctl.h>

bool __read_mostly nsm_use_hostnames;
module_param(nsm_use_hostnames, bool, 0644);

static struct ctl_table my_sysctl[] = {
        {
                .procname       = "nsm_use_hostnames",
                .data           = &nsm_use_hostnames,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
        {}
};

static struct ctl_table my_root[] = {
        {
        .procname       = "mysysctl",
        .mode           = 0555,
        .child          = my_sysctl,
        },
        {}
};

static struct ctl_table_header * my_ctl_header;

static int __init sysctl_exam_init(void)
{
        my_ctl_header = register_sysctl_table(&my_root);
        if (my_ctl_header == NULL)
                printk("error regiester sysctl");

        return 0;
}

static void __exit sysctl_exam_exit(void)
{
        unregister_sysctl_table(my_ctl_header);
}

module_init(sysctl_exam_init);
module_exit(sysctl_exam_exit);
MODULE_LICENSE("GPL");
/****************************************************************/

[root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1   
[root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames 
16777216

After I change the proc_dointvec to new handler proc_dou8vec with the
patch:
[root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1
[root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames
1

In little endian system, there is no such issue.
Already tested in both of big and little endian(ppc64 and ppc64le)

Jia He (2):
  sysctl: introduce new proc handler proc_dobool
  lockd: change the proc_handler for nsm_use_hostnames

 fs/lockd/svc.c         |  2 +-
 include/linux/sysctl.h |  2 ++
 kernel/sysctl.c        | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
-- 
2.5.5

[PATCH v5 1/2] sysctl: introduce new proc handler proc_dobool

[Jia He]

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.

Suggested-by: Pan Xinhui <xinhui@linux.vnet.ibm.com>
Signed-off-by: Jia He <hejianet@gmail.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

[PATCH v5 2/2] lockd: change the proc_handler for nsm_use_hostnames

[Jia He]

nsm_use_hostnames is a module parameter and it will be exported to sysctl
procfs. This is to let user sometimes change it from userspace. But the
minimal unit for sysctl procfs read/write it sizeof(int).
In big endian system, the converting from/to  bool to/from int will cause
error for proc items.

This patch use a new proc_handler proc_dobool to fixe it.

Signed-off-by: Jia He <hejianet@gmail.com>
---
 fs/lockd/svc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index fc4084e..bd6fcf9 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -561,7 +561,7 @@ static struct ctl_table nlm_sysctls[] = {
 		.data		= &nsm_use_hostnames,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dobool,
 	},
 	{
 		.procname	= "nsm_local_state",
-- 
2.5.5

Re: [PATCH v5 2/2] lockd: change the proc_handler for nsm_use_hostnames

[Pan Xinhui]

在 2016/12/15 15:24, Jia He 写道:
> nsm_use_hostnames is a module parameter and it will be exported to sysctl
> procfs. This is to let user sometimes change it from userspace. But the
> minimal unit for sysctl procfs read/write it sizeof(int).
					^^^is^^^
> In big endian system, the converting from/to  bool to/from int will cause
> error for proc items.
>
> This patch use a new proc_handler proc_dobool to fixe it.
						 ^^^fix^^^	
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
other than that is okay for me.

Reviewed-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>

>  fs/lockd/svc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> index fc4084e..bd6fcf9 100644
> --- a/fs/lockd/svc.c
> +++ b/fs/lockd/svc.c
> @@ -561,7 +561,7 @@ static struct ctl_table nlm_sysctls[] = {
>  		.data		= &nsm_use_hostnames,
>  		.maxlen		= sizeof(int),
>  		.mode		= 0644,
> -		.proc_handler	= proc_dointvec,
> +		.proc_handler	= proc_dobool,
>  	},
>  	{
>  		.procname	= "nsm_local_state",
>

Re: [PATCH v5 1/2] sysctl: introduce new proc handler proc_dobool

[Pan Xinhui]

在 2016/12/15 15:24, Jia He 写道:
> 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.
>
> Suggested-by: Pan Xinhui <xinhui@linux.vnet.ibm.com>
> Signed-off-by: Jia He <hejianet@gmail.com>
> ---
>  include/linux/sysctl.h |  2 ++
>  kernel/sysctl.c        | 41 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 43 insertions(+)
>

Reviewed-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>

> 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);
>

Re: [PATCH v5 0/2] change the proc handler for nsm_use_hostnames

[hejianet]

Ping, any comments are welcome. Thanks

B.R.

Jia


On 15/12/2016 3:24 PM, Jia He wrote:
> nsm_use_hostnames is a module parameter and it will be exported to sysctl
> procfs. This is to let user sometimes change it from userspace. But the
> minimal unit for sysctl procfs read/write it sizeof(int).
> In big endian system, the converting from/to  bool to/from int will cause
> error for proc items.
>
> This patch introduces a new proc handler proc_dobool for nsm_use_hostnames.
>
> Changes:
> v5: Fix compilation error when CONFIG_PROC_SYSCTL is not set
> v4: Change (u8 *) to (bool *)
> v3: Introduce a new proc handler proc_dou8vec(suggested by Xinhui Pan)
> v2: Change extern type in lockd.h
>
> The test case I used:
> /***************************************************************/
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/sysctl.h>
>
> bool __read_mostly nsm_use_hostnames;
> module_param(nsm_use_hostnames, bool, 0644);
>
> static struct ctl_table my_sysctl[] = {
>          {
>                  .procname       = "nsm_use_hostnames",
>                  .data           = &nsm_use_hostnames,
>                  .maxlen         = sizeof(int),
>                  .mode           = 0644,
>                  .proc_handler   = &proc_dointvec,
>          },
>          {}
> };
>
> static struct ctl_table my_root[] = {
>          {
>          .procname       = "mysysctl",
>          .mode           = 0555,
>          .child          = my_sysctl,
>          },
>          {}
> };
>
> static struct ctl_table_header * my_ctl_header;
>
> static int __init sysctl_exam_init(void)
> {
>          my_ctl_header = register_sysctl_table(&my_root);
>          if (my_ctl_header == NULL)
>                  printk("error regiester sysctl");
>
>          return 0;
> }
>
> static void __exit sysctl_exam_exit(void)
> {
>          unregister_sysctl_table(my_ctl_header);
> }
>
> module_init(sysctl_exam_init);
> module_exit(sysctl_exam_exit);
> MODULE_LICENSE("GPL");
> /****************************************************************/
>
> [root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1
> [root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames
> 16777216
>
> After I change the proc_dointvec to new handler proc_dou8vec with the
> patch:
> [root@bigendian my]# insmod -f /root/my/hello.ko nsm_use_hostnames=1
> [root@bigendian my]# cat /proc/sys/mysysctl/nsm_use_hostnames
> 1
>
> In little endian system, there is no such issue.
> Already tested in both of big and little endian(ppc64 and ppc64le)
>
> Jia He (2):
>    sysctl: introduce new proc handler proc_dobool
>    lockd: change the proc_handler for nsm_use_hostnames
>
>   fs/lockd/svc.c         |  2 +-
>   include/linux/sysctl.h |  2 ++
>   kernel/sysctl.c        | 41 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 44 insertions(+), 1 deletion(-)

Re: [PATCH v5 1/2] sysctl: introduce new proc handler proc_dobool

[J. Bruce Fields]

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?

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@linux.vnet.ibm.com>
> Signed-off-by: Jia He <hejianet@gmail.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

Re: [PATCH v5 1/2] sysctl: introduce new proc handler proc_dobool

[hejianet]

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@linux.vnet.ibm.com>
>> Signed-off-by: Jia He <hejianet@gmail.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