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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
	bigeasy@linutronix.de, ebiederm@xmission.com
Subject: Re: [PATCH v2 1/2] rcu: Update documentation of rcu_read_unlock()
Date: Fri, 25 May 2018 07:19:42 -0700	[thread overview]
Message-ID: <20180525141942.GB3803@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180525090507.22248-2-anna-maria@linutronix.de>

On Fri, May 25, 2018 at 11:05:06AM +0200, Anna-Maria Gleixner wrote:
> Since commit b4abf91047cf ("rtmutex: Make wait_lock irq safe") the
> explanation in rcu_read_unlock() documentation about irq unsafe rtmutex
> wait_lock is no longer valid.
> 
> Remove it to prevent kernel developers reading the documentation to rely on
> it.
> 
> Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Or let me know if you would like me to carry this patch.  Either way,
just let me know!

							Thanx, Paul

> ---
>  include/linux/rcupdate.h | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 36360d07f25b..64644fda3b22 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -653,9 +653,7 @@ static inline void rcu_read_lock(void)
>   * Unfortunately, this function acquires the scheduler's runqueue and
>   * priority-inheritance spinlocks.  This means that deadlock could result
>   * if the caller of rcu_read_unlock() already holds one of these locks or
> - * any lock that is ever acquired while holding them; or any lock which
> - * can be taken from interrupt context because rcu_boost()->rt_mutex_lock()
> - * does not disable irqs while taking ->wait_lock.
> + * any lock that is ever acquired while holding them.
>   *
>   * That said, RCU readers are never priority boosted unless they were
>   * preempted.  Therefore, one way to avoid deadlock is to make sure
> -- 
> 2.15.1
> 

  reply	other threads:[~2018-05-25 14:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-25  9:05 [PATCH v2 0/2] rtmutex wait_lock is irq safe Anna-Maria Gleixner
2018-05-25  9:05 ` [PATCH v2 1/2] rcu: Update documentation of rcu_read_unlock() Anna-Maria Gleixner
2018-05-25 14:19   ` Paul E. McKenney [this message]
2018-05-28  9:49     ` Anna-Maria Gleixner
2018-06-10  4:18   ` [tip:core/urgent] " tip-bot for Anna-Maria Gleixner
2018-05-25  9:05 ` [PATCH v2 2/2] signal: Remove no longer required irqsave/restore Anna-Maria Gleixner
2018-06-10  4:19   ` [tip:core/urgent] " tip-bot for Anna-Maria Gleixner
2018-05-25 20:02 ` [PATCH v2 0/2] rtmutex wait_lock is irq safe Eric W. Biederman

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