[PATCH] kernel/sysctl: Resolve missing-field-initializers warnings

[PATCH] kernel/sysctl: Resolve missing-field-initializers warnings

[Jeff Kirsher]

From: Mark Rustad <mark.d.rustad@intel.com>

Resolve missing-field-initializers warnings in W=2 builds by
using designated initialization.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
 kernel/sysctl.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4aada6d..5623845 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -257,7 +257,7 @@ static struct ctl_table sysctl_base_table[] = {
 		.mode		= 0555,
 		.child		= dev_table,
 	},
-	{ }
+	{ .procname = NULL }
 };
 
 #ifdef CONFIG_SCHED_DEBUG
@@ -1103,7 +1103,7 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-	{ }
+	{ .procname = NULL }
 };
 
 static struct ctl_table vm_table[] = {
@@ -1485,12 +1485,12 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
 	},
-	{ }
+	{ .procname = NULL }
 };
 
 #if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
 static struct ctl_table binfmt_misc_table[] = {
-	{ }
+	{ .procname = NULL }
 };
 #endif
 
@@ -1658,7 +1658,7 @@ static struct ctl_table fs_table[] = {
 		.proc_handler	= &pipe_proc_fn,
 		.extra1		= &pipe_min_size,
 	},
-	{ }
+	{ .procname = NULL }
 };
 
 static struct ctl_table debug_table[] = {
@@ -1682,11 +1682,11 @@ static struct ctl_table debug_table[] = {
 		.extra2		= &one,
 	},
 #endif
-	{ }
+	{ .procname = NULL }
 };
 
 static struct ctl_table dev_table[] = {
-	{ }
+	{ .procname = NULL }
 };
 
 int __init sysctl_init(void)
-- 
1.9.3

Re: [PATCH] kernel/sysctl: Resolve missing-field-initializers warnings

[Eric W. Biederman]

Jeff Kirsher <jeffrey.t.kirsher@intel.com> writes:

> From: Mark Rustad <mark.d.rustad@intel.com>
>
> Resolve missing-field-initializers warnings in W=2 builds by
> using designated initialization.

ick.  No.

That gcc warning makes no sense.  In this case heeding it makes the code
significantly uglier and significantly more confusing.

Eric


> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> ---
>  kernel/sysctl.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 4aada6d..5623845 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -257,7 +257,7 @@ static struct ctl_table sysctl_base_table[] = {
>  		.mode		= 0555,
>  		.child		= dev_table,
>  	},
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  #ifdef CONFIG_SCHED_DEBUG
> @@ -1103,7 +1103,7 @@ static struct ctl_table kern_table[] = {
>  		.proc_handler	= proc_dointvec,
>  	},
>  #endif
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  static struct ctl_table vm_table[] = {
> @@ -1485,12 +1485,12 @@ static struct ctl_table vm_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_doulongvec_minmax,
>  	},
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  #if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
>  static struct ctl_table binfmt_misc_table[] = {
> -	{ }
> +	{ .procname = NULL }
>  };
>  #endif
>  
> @@ -1658,7 +1658,7 @@ static struct ctl_table fs_table[] = {
>  		.proc_handler	= &pipe_proc_fn,
>  		.extra1		= &pipe_min_size,
>  	},
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  static struct ctl_table debug_table[] = {
> @@ -1682,11 +1682,11 @@ static struct ctl_table debug_table[] = {
>  		.extra2		= &one,
>  	},
>  #endif
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  static struct ctl_table dev_table[] = {
> -	{ }
> +	{ .procname = NULL }
>  };
>  
>  int __init sysctl_init(void)

Re: [PATCH] kernel/sysctl: Resolve missing-field-initializers warnings

[Andrew Morton]

On Sat, 18 Oct 2014 17:39:10 -0700 ebiederm@xmission.com (Eric W. Biederman) wrote:

> Jeff Kirsher <jeffrey.t.kirsher@intel.com> writes:
> 
> > From: Mark Rustad <mark.d.rustad@intel.com>
> >
> > Resolve missing-field-initializers warnings in W=2 builds by
> > using designated initialization.
> 
> ick.  No.
> 
> That gcc warning makes no sense.  In this case heeding it makes the code
> significantly uglier and significantly more confusing.
> 

Yeah, it's not pretty.

> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -257,7 +257,7 @@ static struct ctl_table sysctl_base_table[] = {
> >  		.mode		= 0555,
> >  		.child		= dev_table,
> >  	},
> > -	{ }
> > +	{ .procname = NULL }
> >  };

We use { } to mean "all zero" in 12 squillion places.  Do they all warn
or is there something special about this site?

Re: [PATCH] kernel/sysctl: Resolve missing-field-initializers warnings

[Rustad, Mark D]

[-- Attachment #1: Type: text/plain, Size: 2558 bytes --]

On Oct 21, 2014, at 12:07 PM, Andrew Morton <akpm@linux-foundation.org> wrote:

> On Sat, 18 Oct 2014 17:39:10 -0700 ebiederm@xmission.com (Eric W. Biederman) wrote:
> 
>> Jeff Kirsher <jeffrey.t.kirsher@intel.com> writes:
>> 
>>> From: Mark Rustad <mark.d.rustad@intel.com>
>>> 
>>> Resolve missing-field-initializers warnings in W=2 builds by
>>> using designated initialization.
>> 
>> ick.  No.
>> 
>> That gcc warning makes no sense.  In this case heeding it makes the code
>> significantly uglier and significantly more confusing.
>> 
> 
> Yeah, it's not pretty.
> 
>>> --- a/kernel/sysctl.c
>>> +++ b/kernel/sysctl.c
>>> @@ -257,7 +257,7 @@ static struct ctl_table sysctl_base_table[] = {
>>> 		.mode		= 0555,
>>> 		.child		= dev_table,
>>> 	},
>>> -	{ }
>>> +	{ .procname = NULL }
>>> };
> 
> We use { } to mean "all zero" in 12 squillion places.  Do they all warn
> or is there something special about this site?

Well, about 6 squillion of them are { }, a GCC extension, and the other 6 squillion are { 0 }. Both forms generate the warning. There is nothing special about this site. I just was resolving warnings in order to find some that had some significance. A flood of 125,000 warnings is too awful to look at. I got it down to around 1,500 and did find a few hazards and sent patches to address them, which have been accepted in one form or another.

I had sent patches to add diagnostic control macros to allow a warning to be turned off for a range of code. I would have liked to use them to provide something like a ZERO_ENTRY macro that would have looked something like this:

#define ZERO_ENTRY DIAG_PUSH DIAG_IGNORE(missing-field-initializers) { 0 } DIAG_POP

which would have provided a standard way to get a zero entry that would have avoided the warnings. Borislav was quite opposed to the notion of diagnostic control macros. I rather like the notion as long as their use is tightly controlled.

I'm sure that we both feel that there should be a form that the compiler does not generate this warning for as a preferred solution. The designated initialization is at best a 3rd-best solution, though naming the field used to identify the end of the table is not a bad thing either.

I do like enabling lots of additional warnings to find problems in code, but when it results in such a flood of messages it is not a very useful approach, hence my tendency to want to address them somehow, so that meaningful ones can be noticed.

-- 
Mark Rustad, Networking Division, Intel Corporation


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