crash_dump: Constify struct configfs_item_operations and configfs_group_operations

[PATCH] crash_dump: Constify struct configfs_item_operations and configfs_group_operations

Posted by Christophe JAILLET 1 day, 4 hours ago

'struct configfs_item_operations' and 'configfs_group_operations' are not
modified in this driver.

Constifying these structures moves some data to a read-only section, so
increases overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig, as an example:
Before:
======
   text	   data	    bss	    dec	    hex	filename
  16339	  11001	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
  16499	  10841	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
Compile tested only.

This change is possible since commits f2f36500a63b and f7f78098690d.
---
 kernel/crash_dump_dm_crypt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
index 401423ba477d..0d23dc1de67c 100644
--- a/kernel/crash_dump_dm_crypt.c
+++ b/kernel/crash_dump_dm_crypt.c
@@ -223,7 +223,7 @@ static void config_key_release(struct config_item *item)
 	key_count--;
 }
 
-static struct configfs_item_operations config_key_item_ops = {
+static const struct configfs_item_operations config_key_item_ops = {
 	.release = config_key_release,
 };
 
@@ -298,7 +298,7 @@ static struct configfs_attribute *config_keys_attrs[] = {
  * Note that, since no extra work is required on ->drop_item(),
  * no ->drop_item() is provided.
  */
-static struct configfs_group_operations config_keys_group_ops = {
+static const struct configfs_group_operations config_keys_group_ops = {
 	.make_item = config_keys_make_item,
 };
 
-- 
2.52.0

Re: [PATCH] crash_dump: Constify struct configfs_item_operations and configfs_group_operations

Posted by Baoquan He 20 hours ago

On 12/14/25 at 06:57pm, Christophe JAILLET wrote:
> 'struct configfs_item_operations' and 'configfs_group_operations' are not
> modified in this driver.
> 
> Constifying these structures moves some data to a read-only section, so
> increases overall security, especially when the structure holds some
> function pointers.
> 
> On a x86_64, with allmodconfig, as an example:
> Before:
> ======
>    text	   data	    bss	    dec	    hex	filename
>   16339	  11001	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
> 
> After:
> =====
>    text	   data	    bss	    dec	    hex	filename
>   16499	  10841	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Sounds not bad, leave this to Coiby to test.

> ---
> Compile tested only.
> 
> This change is possible since commits f2f36500a63b and f7f78098690d.

I don't follow here, why do these two commits have anything with this
patch?

> ---
>  kernel/crash_dump_dm_crypt.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
> index 401423ba477d..0d23dc1de67c 100644
> --- a/kernel/crash_dump_dm_crypt.c
> +++ b/kernel/crash_dump_dm_crypt.c
> @@ -223,7 +223,7 @@ static void config_key_release(struct config_item *item)
>  	key_count--;
>  }
>  
> -static struct configfs_item_operations config_key_item_ops = {
> +static const struct configfs_item_operations config_key_item_ops = {
>  	.release = config_key_release,
>  };
>  
> @@ -298,7 +298,7 @@ static struct configfs_attribute *config_keys_attrs[] = {
>   * Note that, since no extra work is required on ->drop_item(),
>   * no ->drop_item() is provided.
>   */
> -static struct configfs_group_operations config_keys_group_ops = {
> +static const struct configfs_group_operations config_keys_group_ops = {
>  	.make_item = config_keys_make_item,
>  };
>  
> -- 
> 2.52.0
> 
>

Re: [PATCH] crash_dump: Constify struct configfs_item_operations and configfs_group_operations

Posted by Christophe JAILLET 15 hours ago

Le 15/12/2025 à 03:13, Baoquan He a écrit :
> On 12/14/25 at 06:57pm, Christophe JAILLET wrote:
>> 'struct configfs_item_operations' and 'configfs_group_operations' are not
>> modified in this driver.
>>
>> Constifying these structures moves some data to a read-only section, so
>> increases overall security, especially when the structure holds some
>> function pointers.
>>
>> On a x86_64, with allmodconfig, as an example:
>> Before:
>> ======
>>     text	   data	    bss	    dec	    hex	filename
>>    16339	  11001	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
>>
>> After:
>> =====
>>     text	   data	    bss	    dec	    hex	filename
>>    16499	  10841	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
>>
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> 
> Sounds not bad, leave this to Coiby to test.
> 
>> ---
>> Compile tested only.
>>
>> This change is possible since commits f2f36500a63b and f7f78098690d.
> 
> I don't follow here, why do these two commits have anything with this
> patch?

Without these patches, it won't compile because "struct 
config_item_type" needs to be tweaked to accept some const field. It is 
what is done by these patches that have landed 2 weeks ago or so.


Without these 2 commits, you would get (with French messages, sorry):

   CC      kernel/crash_dump_dm_crypt.o
kernel/crash_dump_dm_crypt.c:231:24: erreur: l'initialisation abandonne 
le qualificatif « const » du type pointé [-Werror=discarded-qualifiers]
   231 |         .ct_item_ops = &config_key_item_ops,
       |                        ^
kernel/crash_dump_dm_crypt.c:306:25: erreur: l'initialisation abandonne 
le qualificatif « const » du type pointé [-Werror=discarded-qualifiers]
   306 |         .ct_group_ops = &config_keys_group_ops,
       |                         ^

CJ

> 
>> ---
>>   kernel/crash_dump_dm_crypt.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
>> index 401423ba477d..0d23dc1de67c 100644
>> --- a/kernel/crash_dump_dm_crypt.c
>> +++ b/kernel/crash_dump_dm_crypt.c
>> @@ -223,7 +223,7 @@ static void config_key_release(struct config_item *item)
>>   	key_count--;
>>   }
>>   
>> -static struct configfs_item_operations config_key_item_ops = {
>> +static const struct configfs_item_operations config_key_item_ops = {
>>   	.release = config_key_release,
>>   };
>>   
>> @@ -298,7 +298,7 @@ static struct configfs_attribute *config_keys_attrs[] = {
>>    * Note that, since no extra work is required on ->drop_item(),
>>    * no ->drop_item() is provided.
>>    */
>> -static struct configfs_group_operations config_keys_group_ops = {
>> +static const struct configfs_group_operations config_keys_group_ops = {
>>   	.make_item = config_keys_make_item,
>>   };
>>   
>> -- 
>> 2.52.0
>>
>>
> 
> 
>

Re: [PATCH] crash_dump: Constify struct configfs_item_operations and configfs_group_operations

Posted by Baoquan He 12 hours ago

On 12/15/25 at 08:19am, Christophe JAILLET wrote:
> Le 15/12/2025 à 03:13, Baoquan He a écrit :
> > On 12/14/25 at 06:57pm, Christophe JAILLET wrote:
> > > 'struct configfs_item_operations' and 'configfs_group_operations' are not
> > > modified in this driver.
> > > 
> > > Constifying these structures moves some data to a read-only section, so
> > > increases overall security, especially when the structure holds some
> > > function pointers.
> > > 
> > > On a x86_64, with allmodconfig, as an example:
> > > Before:
> > > ======
> > >     text	   data	    bss	    dec	    hex	filename
> > >    16339	  11001	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
> > > 
> > > After:
> > > =====
> > >     text	   data	    bss	    dec	    hex	filename
> > >    16499	  10841	    384	  27724	   6c4c	kernel/crash_dump_dm_crypt.o
> > > 
> > > Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> > 
> > Sounds not bad, leave this to Coiby to test.
> > 
> > > ---
> > > Compile tested only.
> > > 
> > > This change is possible since commits f2f36500a63b and f7f78098690d.
> > 
> > I don't follow here, why do these two commits have anything with this
> > patch?
> 
> Without these patches, it won't compile because "struct config_item_type"
> needs to be tweaked to accept some const field. It is what is done by these
> patches that have landed 2 weeks ago or so.
> 
> 
> Without these 2 commits, you would get (with French messages, sorry):
> 
>   CC      kernel/crash_dump_dm_crypt.o
> kernel/crash_dump_dm_crypt.c:231:24: erreur: l'initialisation abandonne le
> qualificatif « const » du type pointé [-Werror=discarded-qualifiers]
>   231 |         .ct_item_ops = &config_key_item_ops,
>       |                        ^
> kernel/crash_dump_dm_crypt.c:306:25: erreur: l'initialisation abandonne le
> qualificatif « const » du type pointé [-Werror=discarded-qualifiers]
>   306 |         .ct_group_ops = &config_keys_group_ops,
>       |                         ^

Ah, I see now. Thanks for the information.

> 
> > 
> > > ---
> > >   kernel/crash_dump_dm_crypt.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
> > > index 401423ba477d..0d23dc1de67c 100644
> > > --- a/kernel/crash_dump_dm_crypt.c
> > > +++ b/kernel/crash_dump_dm_crypt.c
> > > @@ -223,7 +223,7 @@ static void config_key_release(struct config_item *item)
> > >   	key_count--;
> > >   }
> > > -static struct configfs_item_operations config_key_item_ops = {
> > > +static const struct configfs_item_operations config_key_item_ops = {
> > >   	.release = config_key_release,
> > >   };
> > > @@ -298,7 +298,7 @@ static struct configfs_attribute *config_keys_attrs[] = {
> > >    * Note that, since no extra work is required on ->drop_item(),
> > >    * no ->drop_item() is provided.
> > >    */
> > > -static struct configfs_group_operations config_keys_group_ops = {
> > > +static const struct configfs_group_operations config_keys_group_ops = {
> > >   	.make_item = config_keys_make_item,
> > >   };
> > > -- 
> > > 2.52.0
> > > 
> > > 
> > 
> > 
> > 
>