linux-kernel - Re: [PATCH] rtc: Make rtc_update

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]

Message-Id: <20090409153921.04b6384c.akpm@linux-foundation.org>
Date:	Thu, 9 Apr 2009 15:39:21 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Atsushi Nemoto <anemo@....ocn.ne.jp>
Cc:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rtc: Make rtc_update_irq callable with irqs enabled

On Tue,  7 Apr 2009 01:50:31 +0900
Atsushi Nemoto <anemo@....ocn.ne.jp> wrote:

> The rtc_update_irq() might be called with irqs enabled, if a interrupt
> handler was registered without IRQF_DISABLED.

Why?  What are the consequences of not merging the patch?  Is it a
bugfix?  If so, what are the user-visible effects of the bug?

See, I need to decide if this patch is needed in 2.6.30 (and earlier),
but the changelog doesn't include enough info to make that decision.

> Use spin_lock_irqsave/spin_unlock_irqrestore instead of
> spin_lock/spin_unlock.
> 
> Signed-off-by: Atsushi Nemoto <anemo@....ocn.ne.jp>
> ---
>  drivers/rtc/interface.c |   10 ++++++----
>  1 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index 4348c4b..a8641f7 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -376,14 +376,16 @@ EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
>  void rtc_update_irq(struct rtc_device *rtc,
>  		unsigned long num, unsigned long events)
>  {
> -	spin_lock(&rtc->irq_lock);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rtc->irq_lock, flags);
>  	rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
> -	spin_unlock(&rtc->irq_lock);
> +	spin_unlock_irqrestore(&rtc->irq_lock, flags);
>  
> -	spin_lock(&rtc->irq_task_lock);
> +	spin_lock_irqsave(&rtc->irq_task_lock, flags);
>  	if (rtc->irq_task)
>  		rtc->irq_task->func(rtc->irq_task->private_data);
> -	spin_unlock(&rtc->irq_task_lock);
> +	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
>  
>  	wake_up_interruptible(&rtc->irq_queue);
>  	kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);

--
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/