linux-kernel - Re: [PATCH] lockdep: Include print_collision and helper functions in DEBUG

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Date:	Fri, 15 Apr 2016 10:06:44 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Ingo Molnar <mingo@...hat.com>
Cc:	Yang Shi <yang.shi@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnd Bergmann <arnd@...db.de>,
	LKML <linux-kernel@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	Alfredo Alvarez Fernandez <alfredoalvarezfernandez@...il.com>
Subject: Re: [PATCH] lockdep: Include print_collision and helper functions in DEBUG_LOCKDEP

On Wed, Apr 13, 2016 at 5:57 PM, Yang Shi <yang.shi@...aro.org> wrote:
> pint_collosion and helper functions are just used when DEBUG_LOCKDEP is
> selected, so include them in #ifdef CONFIG_DEBUG_LOCKDEP to avoid the below
> "defined but not used" warning when DEBUG_LOCKDEP is off:
>
> kernel/locking/lockdep.c:2051:13: warning: 'print_collision' defined but not used [-Wunused-function]
>  static void print_collision(struct task_struct *curr,
>
> Signed-off-by: Yang Shi <yang.shi@...aro.org>

Thanks, I had noticed this warning too.

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  kernel/locking/lockdep.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 2324ba5..ed94109 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -1999,6 +1999,7 @@ static inline int get_first_held_lock(struct task_struct *curr,
>         return ++i;
>  }
>
> +#ifdef CONFIG_DEBUG_LOCKDEP
>  /*
>   * Returns the next chain_key iteration
>   */
> @@ -2069,6 +2070,7 @@ static void print_collision(struct task_struct *curr,
>         printk("\nstack backtrace:\n");
>         dump_stack();
>  }
> +#endif
>
>  /*
>   * Checks whether the chain and the current held locks are consistent
> --
> 2.0.2
>



-- 
Kees Cook
Chrome OS & Brillo Security