staging: greybus: audio_manager: make envp[] static const

[PATCH] staging: greybus: audio_manager: make envp[] static const

Posted by Sameeksha Sankpal 1 week, 2 days ago

The envp[] array contains string literals and is never modified.
Declare it as 'static const char * const' to place it in read-only
memory and avoid unnecessary stack usage.

This fixes a checkpatch warning:
"char * array declaration might be better as static const"

Signed-off-by: Sameeksha Sankpal <sameekshasankpal@gmail.com>
---
 drivers/staging/greybus/audio_manager_module.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/audio_manager_module.c b/drivers/staging/greybus/audio_manager_module.c
index 4a4dfb42f50f..1b83c05f2434 100644
--- a/drivers/staging/greybus/audio_manager_module.c
+++ b/drivers/staging/greybus/audio_manager_module.c
@@ -159,7 +159,7 @@ static void send_add_uevent(struct gb_audio_manager_module *module)
 	char ip_devices_string[64];
 	char op_devices_string[64];
 
-	char *envp[] = {
+	static const char * const envp[] = {
 		name_string,
 		vid_string,
 		pid_string,
-- 
2.43.0

Re: [PATCH] staging: greybus: audio_manager: make envp[] static const

Posted by Greg KH 1 week ago

On Sat, Nov 22, 2025 at 02:08:13PM +0530, Sameeksha Sankpal wrote:
> The envp[] array contains string literals and is never modified.
> Declare it as 'static const char * const' to place it in read-only
> memory and avoid unnecessary stack usage.
> 
> This fixes a checkpatch warning:
> "char * array declaration might be better as static const"
> 
> Signed-off-by: Sameeksha Sankpal <sameekshasankpal@gmail.com>
> ---
>  drivers/staging/greybus/audio_manager_module.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/greybus/audio_manager_module.c b/drivers/staging/greybus/audio_manager_module.c
> index 4a4dfb42f50f..1b83c05f2434 100644
> --- a/drivers/staging/greybus/audio_manager_module.c
> +++ b/drivers/staging/greybus/audio_manager_module.c
> @@ -159,7 +159,7 @@ static void send_add_uevent(struct gb_audio_manager_module *module)
>  	char ip_devices_string[64];
>  	char op_devices_string[64];
>  
> -	char *envp[] = {
> +	static const char * const envp[] = {
>  		name_string,
>  		vid_string,
>  		pid_string,
> -- 
> 2.43.0
> 
> 

Any specific reason why you did not build this patch before submitting
it?  Please always do so.

thanks,

greg k-h

Re: [PATCH] staging: greybus: audio_manager: make envp[] static const

Posted by kernel test robot 1 week ago

Hi Sameeksha,

kernel test robot noticed the following build errors:

[auto build test ERROR on staging/staging-testing]

url:    https://github.com/intel-lab-lkp/linux/commits/Sameeksha-Sankpal/staging-greybus-audio_manager-make-envp-static-const/20251122-163906
base:   staging/staging-testing
patch link:    https://lore.kernel.org/r/20251122083814.49753-1-sameekshasankpal%40gmail.com
patch subject: [PATCH] staging: greybus: audio_manager: make envp[] static const
config: s390-allmodconfig (https://download.01.org/0day-ci/archive/20251124/202511241614.lkKJF5B6-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251124/202511241614.lkKJF5B6-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511241614.lkKJF5B6-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/staging/greybus/audio_manager_module.c:163:3: error: initializer element is not a compile-time constant
     163 |                 name_string,
         |                 ^~~~~~~~~~~
>> drivers/staging/greybus/audio_manager_module.c:181:46: error: passing 'const char *const[7]' to parameter of type 'char **' discards qualifiers in nested pointer types [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
     181 |         kobject_uevent_env(&module->kobj, KOBJ_ADD, envp);
         |                                                     ^~~~
   include/linux/kobject.h:216:10: note: passing argument to parameter 'envp' here
     216 |                         char *envp[]);
         |                               ^
   2 errors generated.


vim +163 drivers/staging/greybus/audio_manager_module.c

8db00736d365b7 Svetlin Ankov     2016-01-13  152  
8db00736d365b7 Svetlin Ankov     2016-01-13  153  static void send_add_uevent(struct gb_audio_manager_module *module)
8db00736d365b7 Svetlin Ankov     2016-01-13  154  {
8db00736d365b7 Svetlin Ankov     2016-01-13  155  	char name_string[128];
8db00736d365b7 Svetlin Ankov     2016-01-13  156  	char vid_string[64];
8db00736d365b7 Svetlin Ankov     2016-01-13  157  	char pid_string[64];
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  158  	char intf_id_string[64];
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  159  	char ip_devices_string[64];
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  160  	char op_devices_string[64];
8db00736d365b7 Svetlin Ankov     2016-01-13  161  
c78cfcfa51fa58 Sameeksha Sankpal 2025-11-22  162  	static const char * const envp[] = {
8db00736d365b7 Svetlin Ankov     2016-01-13 @163  		name_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  164  		vid_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  165  		pid_string,
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  166  		intf_id_string,
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  167  		ip_devices_string,
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  168  		op_devices_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  169  		NULL
8db00736d365b7 Svetlin Ankov     2016-01-13  170  	};
8db00736d365b7 Svetlin Ankov     2016-01-13  171  
8db00736d365b7 Svetlin Ankov     2016-01-13  172  	snprintf(name_string, 128, "NAME=%s", module->desc.name);
8db00736d365b7 Svetlin Ankov     2016-01-13  173  	snprintf(vid_string, 64, "VID=%d", module->desc.vid);
8db00736d365b7 Svetlin Ankov     2016-01-13  174  	snprintf(pid_string, 64, "PID=%d", module->desc.pid);
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  175  	snprintf(intf_id_string, 64, "INTF_ID=%d", module->desc.intf_id);
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  176  	snprintf(ip_devices_string, 64, "I/P DEVICES=0x%X",
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  177  		 module->desc.ip_devices);
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  178  	snprintf(op_devices_string, 64, "O/P DEVICES=0x%X",
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  179  		 module->desc.op_devices);
8db00736d365b7 Svetlin Ankov     2016-01-13  180  
8db00736d365b7 Svetlin Ankov     2016-01-13 @181  	kobject_uevent_env(&module->kobj, KOBJ_ADD, envp);
8db00736d365b7 Svetlin Ankov     2016-01-13  182  }
8db00736d365b7 Svetlin Ankov     2016-01-13  183  

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https://github.com/intel/lkp-tests/wiki

Re: [PATCH] staging: greybus: audio_manager: make envp[] static const

Posted by kernel test robot 1 week ago

Hi Sameeksha,

kernel test robot noticed the following build errors:

[auto build test ERROR on staging/staging-testing]

url:    https://github.com/intel-lab-lkp/linux/commits/Sameeksha-Sankpal/staging-greybus-audio_manager-make-envp-static-const/20251122-163906
base:   staging/staging-testing
patch link:    https://lore.kernel.org/r/20251122083814.49753-1-sameekshasankpal%40gmail.com
patch subject: [PATCH] staging: greybus: audio_manager: make envp[] static const
config: i386-randconfig-007-20251124 (https://download.01.org/0day-ci/archive/20251124/202511241504.tsKxZp9G-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251124/202511241504.tsKxZp9G-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511241504.tsKxZp9G-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/staging/greybus/audio_manager_module.c: In function 'send_add_uevent':
>> drivers/staging/greybus/audio_manager_module.c:163:17: error: initializer element is not constant
     163 |                 name_string,
         |                 ^~~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:163:17: note: (near initialization for 'envp[0]')
   drivers/staging/greybus/audio_manager_module.c:164:17: error: initializer element is not constant
     164 |                 vid_string,
         |                 ^~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:164:17: note: (near initialization for 'envp[1]')
   drivers/staging/greybus/audio_manager_module.c:165:17: error: initializer element is not constant
     165 |                 pid_string,
         |                 ^~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:165:17: note: (near initialization for 'envp[2]')
   drivers/staging/greybus/audio_manager_module.c:166:17: error: initializer element is not constant
     166 |                 intf_id_string,
         |                 ^~~~~~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:166:17: note: (near initialization for 'envp[3]')
   drivers/staging/greybus/audio_manager_module.c:167:17: error: initializer element is not constant
     167 |                 ip_devices_string,
         |                 ^~~~~~~~~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:167:17: note: (near initialization for 'envp[4]')
   drivers/staging/greybus/audio_manager_module.c:168:17: error: initializer element is not constant
     168 |                 op_devices_string,
         |                 ^~~~~~~~~~~~~~~~~
   drivers/staging/greybus/audio_manager_module.c:168:17: note: (near initialization for 'envp[5]')
>> drivers/staging/greybus/audio_manager_module.c:181:53: error: passing argument 3 of 'kobject_uevent_env' from incompatible pointer type [-Wincompatible-pointer-types]
     181 |         kobject_uevent_env(&module->kobj, KOBJ_ADD, envp);
         |                                                     ^~~~
         |                                                     |
         |                                                     const char * const*
   In file included from drivers/staging/greybus/audio_manager.h:11,
                    from drivers/staging/greybus/audio_manager_module.c:10:
   include/linux/kobject.h:216:31: note: expected 'char **' but argument is of type 'const char * const*'
     216 |                         char *envp[]);
         |                         ~~~~~~^~~~~~


vim +163 drivers/staging/greybus/audio_manager_module.c

8db00736d365b7 Svetlin Ankov     2016-01-13  152  
8db00736d365b7 Svetlin Ankov     2016-01-13  153  static void send_add_uevent(struct gb_audio_manager_module *module)
8db00736d365b7 Svetlin Ankov     2016-01-13  154  {
8db00736d365b7 Svetlin Ankov     2016-01-13  155  	char name_string[128];
8db00736d365b7 Svetlin Ankov     2016-01-13  156  	char vid_string[64];
8db00736d365b7 Svetlin Ankov     2016-01-13  157  	char pid_string[64];
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  158  	char intf_id_string[64];
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  159  	char ip_devices_string[64];
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  160  	char op_devices_string[64];
8db00736d365b7 Svetlin Ankov     2016-01-13  161  
c78cfcfa51fa58 Sameeksha Sankpal 2025-11-22  162  	static const char * const envp[] = {
8db00736d365b7 Svetlin Ankov     2016-01-13 @163  		name_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  164  		vid_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  165  		pid_string,
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  166  		intf_id_string,
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  167  		ip_devices_string,
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  168  		op_devices_string,
8db00736d365b7 Svetlin Ankov     2016-01-13  169  		NULL
8db00736d365b7 Svetlin Ankov     2016-01-13  170  	};
8db00736d365b7 Svetlin Ankov     2016-01-13  171  
8db00736d365b7 Svetlin Ankov     2016-01-13  172  	snprintf(name_string, 128, "NAME=%s", module->desc.name);
8db00736d365b7 Svetlin Ankov     2016-01-13  173  	snprintf(vid_string, 64, "VID=%d", module->desc.vid);
8db00736d365b7 Svetlin Ankov     2016-01-13  174  	snprintf(pid_string, 64, "PID=%d", module->desc.pid);
d0af1bd5f6f449 Pankaj Bharadiya  2016-10-16  175  	snprintf(intf_id_string, 64, "INTF_ID=%d", module->desc.intf_id);
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  176  	snprintf(ip_devices_string, 64, "I/P DEVICES=0x%X",
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  177  		 module->desc.ip_devices);
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  178  	snprintf(op_devices_string, 64, "O/P DEVICES=0x%X",
a9234bfd6cec44 Vaibhav Agarwal   2016-03-30  179  		 module->desc.op_devices);
8db00736d365b7 Svetlin Ankov     2016-01-13  180  
8db00736d365b7 Svetlin Ankov     2016-01-13 @181  	kobject_uevent_env(&module->kobj, KOBJ_ADD, envp);
8db00736d365b7 Svetlin Ankov     2016-01-13  182  }
8db00736d365b7 Svetlin Ankov     2016-01-13  183  

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