linux-kernel - Re: [PATCH 4/4] posix-timers: turn it_signal into it

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Date:	Fri, 02 Sep 2011 13:49:58 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Andi Kleen <andi@...stfloor.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH 4/4] posix-timers: turn it_signal into it_valid flag

Le vendredi 02 septembre 2011 à 12:06 +0200, Thomas Gleixner a écrit :

> ------------------>
> Subject: posix-timers: Simplify deletion protection
> From: Thomas Gleixner <tglx@...utronix.de>
> Date: Fri, 02 Sep 2011 11:59:14 +0200
> 
> k_itimer->it_signal is soleley used to protect a timer lookup against
> a concurrent deletion. We can use k_itimer->list for the same purpose.
> 

Well, this patch is wrong too, unless you base it after Andi patch 1/4
(move global timer id management to signal_struct)

The test is also present to make sure one process doesnt try to use a
timer_id of another process.


> @@ -643,7 +643,7 @@ static struct k_itimer *__lock_timer(tim
>  	timr = idr_find(&posix_timers_id, (int)timer_id);
>  	if (timr) {
>  		spin_lock_irqsave(&timr->it_lock, *flags);
> -		if (timr->it_signal == current->signal) {
> +		if (!list_empty(&timr->list)) {
>  			rcu_read_unlock();
>  			return timr;
>  		}



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