Re: [PATCH] sched: Remove nested extern

From: Josh Triplett
Date: Mon Sep 22 2014 - 14:26:04 EST


On Mon, Sep 22, 2014 at 10:55:11AM -0700, Mark D Rustad wrote:
> Avoid W=2 nested-externs warning by moving the nested extern to
> a normal extern. This eliminates that warning which is generated
> for every inclusion of sched.h in a kernel build when W=2 is used.
> This also removes a point of maintenance if the definition of
> delayacct_on were ever to change.
>
> Signed-off-by: Mark Rustad <mark.d.rustad@xxxxxxxxx>

This seems sensible, and makes much more sense than wrapping the extern
in a directive to disable warnings.

Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>

> include/linux/delayacct.h | 1 -
> include/linux/sched.h | 3 ++-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
> index 6cee17c22313..51229790af00 100644
> --- a/include/linux/delayacct.h
> +++ b/include/linux/delayacct.h
> @@ -30,7 +30,6 @@
>
> #ifdef CONFIG_TASK_DELAY_ACCT
>
> -extern int delayacct_on; /* Delay accounting turned on/off */
> extern struct kmem_cache *delayacct_cache;
> extern void delayacct_init(void);
> extern void __delayacct_tsk_init(struct task_struct *);
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 5c2c885ee52b..1f1dcfdcd92c 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -825,6 +825,8 @@ struct task_delay_info {
> u64 freepages_delay; /* wait for memory reclaim */
> u32 freepages_count; /* total count of memory reclaim */
> };
> +
> +extern int delayacct_on; /* Delay accounting turned on/off */
> #endif /* CONFIG_TASK_DELAY_ACCT */
>
> static inline int sched_info_on(void)
> @@ -832,7 +834,6 @@ static inline int sched_info_on(void)
> #ifdef CONFIG_SCHEDSTATS
> return 1;
> #elif defined(CONFIG_TASK_DELAY_ACCT)
> - extern int delayacct_on;
> return delayacct_on;
> #else
> return 0;
>
> --
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