linux-kernel - Re: [PATCH] signal: annotate lock_task

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Message-ID: <AANLkTim3GS+O9DnLZ+nh73DkoNnxa+pyAajjX2O-wb-X@mail.gmail.com>
Date:	Sat, 25 Sep 2010 23:31:02 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>
Cc:	Al Viro <viro@...iv.linux.org.uk>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] signal: annotate lock_task_sighand()

Add missing Cc.


On Sat, Sep 25, 2010 at 23:04, Namhyung Kim <namhyung@...il.com> wrote:
> lock_task_sighand() grabs sighand->siglock in case of returning
> non-NULL but unlock_task_sighand() releases it unconditionally.
> This leads sparse to complain about the lock context imbalance.
> Rename and wrap lock_task_sighand() using __cond_lock() macro
> to make sparse happy.
>
> Suggested-by: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Namhyung Kim <namhyung@...il.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Roland McGrath <roland@...hat.com>

> ---
>  include/linux/sched.h |    9 ++++++++-
>  kernel/signal.c       |    3 ++-
>  2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 1e2a6db..9937998 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2210,9 +2210,16 @@ static inline void task_unlock(struct task_struct *p)
>        spin_unlock(&p->alloc_lock);
>  }
>
> -extern struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
> +extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
>                                                        unsigned long *flags);
>
> +#define lock_task_sighand(tsk, flags)                                  \
> +({     struct sighand_struct *__ss;                                    \
> +       __cond_lock(&(tsk)->sighand->siglock,                           \
> +                   (__ss = __lock_task_sighand(tsk, flags)));          \
> +       __ss;                                                           \
> +})                                                                     \
> +
>  static inline void unlock_task_sighand(struct task_struct *tsk,
>                                                unsigned long *flags)
>  {
> diff --git a/kernel/signal.c b/kernel/signal.c
> index bded651..e4e8cfe 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1105,7 +1105,8 @@ int zap_other_threads(struct task_struct *p)
>        return count;
>  }
>
> -struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
> +struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
> +                                          unsigned long *flags)
>  {
>        struct sighand_struct *sighand;
>
> --
> 1.7.2.2
>
>



-- 
Regards,
Namhyung Kim
--
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