linux-kernel - Re: [patch V3 5/7] rtmutex: Confine deadlock logic to futex

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 9 Jun 2014 20:59:08 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Jason Low <jason.low2@...com>, Brad Mouring <bmouring@...com>
Subject: Re: [patch V3 5/7] rtmutex: Confine deadlock logic to futex

On Mon, 09 Jun 2014 20:28:09 -0000
Thomas Gleixner <tglx@...utronix.de> wrote:
  
> +/*
> + * Futex variant to allow full deadlock detection.
> + */
> +int __rt_mutex_timed_lock(struct rt_mutex *lock,
> +			  struct hrtimer_sleeper *timeout)
> +{
> +	might_sleep();
> +
> +	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, 0,
> +				       rt_mutex_slowlock);
> +}
> +
>  /**
>   * rt_mutex_timed_lock - lock a rt_mutex interruptible
>   *			the timeout structure is provided
>   *			by the caller
>   *
> - * @lock: 		the rt_mutex to be locked
> + * @lock:		the rt_mutex to be locked
>   * @timeout:		timeout structure or NULL (no timeout)
> - * @detect_deadlock:	deadlock detection on/off
>   *
>   * Returns:
> - *  0 		on success
> - * -EINTR 	when interrupted by a signal
> + *  0		on success
> + * -EINTR	when interrupted by a signal
>   * -ETIMEDOUT	when the timeout expired
> - * -EDEADLK	when the lock would deadlock (when deadlock detection is on)
>   */
>  int
> -rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout,
> -		    int detect_deadlock)
> +rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
>  {
>  	might_sleep();
>  
> -	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
> -				       detect_deadlock, rt_mutex_slowlock);
> +	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout, 0,
> +				       rt_mutex_slowlock);
>  }
>  EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
>  

I must be missing something. What's the difference between the above
and the futex variant one? They both do the exact same thing:


int foo(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
{
	might_sleep();

	return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timout,
				       0, rt_mutex_slowlock);
}


??

-- Steve
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/