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[PATCH] dm: ioctl: use kvfree

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  [PATCH] dm: ioctl: use kvfree Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2016-04-11 17:20 +0200
    Re: dm: ioctl: use kvfree Guenter Roeck <linux@roeck-us.net> - 2016-04-11 20:40 +0200

#1376062 — [PATCH] dm: ioctl: use kvfree

We can use kvfree() instead of calling kfree() and vfree() based on
if-else and param_flags. kvfree() will check the type of address and
will call the respective function to free it.
Additionally we can also remove the use of DM_PARAMS_KMALLOC and
DM_PARAMS_VMALLOC.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
---
 drivers/md/dm-ioctl.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 2adf81d..d5df3a5 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1670,8 +1670,6 @@ static int check_version(unsigned int cmd, struct dm_ioctl __user *user)
 	return r;
 }
 
-#define DM_PARAMS_KMALLOC	0x0001	/* Params alloced with kmalloc */
-#define DM_PARAMS_VMALLOC	0x0002	/* Params alloced with vmalloc */
 #define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
 
 static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
@@ -1679,10 +1677,7 @@ static void free_params(struct dm_ioctl *param, size_t param_size, int param_fla
 	if (param_flags & DM_WIPE_BUFFER)
 		memset(param, 0, param_size);
 
-	if (param_flags & DM_PARAMS_KMALLOC)
-		kfree(param);
-	if (param_flags & DM_PARAMS_VMALLOC)
-		vfree(param);
+	kvfree(param);
 }
 
 static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
@@ -1716,8 +1711,6 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 	dmi = NULL;
 	if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
 		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
-		if (dmi)
-			*param_flags |= DM_PARAMS_KMALLOC;
 	}
 
 	if (!dmi) {
@@ -1725,8 +1718,6 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 		noio_flag = memalloc_noio_save();
 		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
 		memalloc_noio_restore(noio_flag);
-		if (dmi)
-			*param_flags |= DM_PARAMS_VMALLOC;
 	}
 
 	if (!dmi) {
-- 
1.9.1

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#1376209 — Re: dm: ioctl: use kvfree

On Mon, Apr 11, 2016 at 08:44:37PM +0530, Sudip Mukherjee wrote:
> We can use kvfree() instead of calling kfree() and vfree() based on
> if-else and param_flags. kvfree() will check the type of address and
> will call the respective function to free it.
> Additionally we can also remove the use of DM_PARAMS_KMALLOC and
> DM_PARAMS_VMALLOC.
> 
> Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
> 
> ---
> drivers/md/dm-ioctl.c | 11 +----------
>  1 file changed, 1 insertion(+), 10 deletions(-)
> 
> diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
> index 2adf81d..d5df3a5 100644
> --- a/drivers/md/dm-ioctl.c
> +++ b/drivers/md/dm-ioctl.c
> @@ -1670,8 +1670,6 @@ static int check_version(unsigned int cmd, struct dm_ioctl __user *user)
>  	return r;
>  }
>  
> -#define DM_PARAMS_KMALLOC	0x0001	/* Params alloced with kmalloc */
> -#define DM_PARAMS_VMALLOC	0x0002	/* Params alloced with vmalloc */
>  #define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
>  
>  static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
> @@ -1679,10 +1677,7 @@ static void free_params(struct dm_ioctl *param, size_t param_size, int param_fla
>  	if (param_flags & DM_WIPE_BUFFER)
>  		memset(param, 0, param_size);
>  
> -	if (param_flags & DM_PARAMS_KMALLOC)
> -		kfree(param);
> -	if (param_flags & DM_PARAMS_VMALLOC)
> -		vfree(param);
> +	kvfree(param);

That won't work: param is not always allocated. See code path leading to
the "data_copied:" label in copy_params().

This is the second time this patch has been submitted. Maybe someone should
add a comment explaining why a conditional flag is needed.

Guenter

>  }
>  
>  static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
> @@ -1716,8 +1711,6 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
>  	dmi = NULL;
>  	if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
>  		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
> -		if (dmi)
> -			*param_flags |= DM_PARAMS_KMALLOC;
>  	}
>  
>  	if (!dmi) {
> @@ -1725,8 +1718,6 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
>  		noio_flag = memalloc_noio_save();
>  		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
>  		memalloc_noio_restore(noio_flag);
> -		if (dmi)
> -			*param_flags |= DM_PARAMS_VMALLOC;
>  	}
>  
>  	if (!dmi) {

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