linux-kernel - Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver

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Message-Id: <20121218164659.a3d3655a.akpm@linux-foundation.org>
Date:	Tue, 18 Dec 2012 16:46:59 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Vincent Palatin <vpalatin@...omium.org>
Cc:	rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	linux-kernel@...r.kernel.org
Subject: Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver

On Thu,  2 Aug 2012 16:53:25 -0700
Vincent Palatin <vpalatin@...omium.org> wrote:

> When calling rtc_device_unregister, we are not freeing the id used by the
> driver.
> So when doing a unload/load cycle for a RTC driver (e.g. rmmod rtc_cmos
> && modprobe rtc_cmos), its id is incremented by one. As a consequence,
> we no longer have neither an rtc0 driver nor a /proc/driver/rtc (as it
> only exists for the first driver).
> 
> Signed-off-by: Vincent Palatin <vpalatin@...omium.org>
> ---
>  drivers/rtc/class.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
> index dc4c274..37b1d82 100644
> --- a/drivers/rtc/class.c
> +++ b/drivers/rtc/class.c
> @@ -238,6 +238,7 @@ void rtc_device_unregister(struct rtc_device *rtc)
>  		rtc_proc_del_device(rtc);
>  		device_unregister(&rtc->dev);
>  		rtc->ops = NULL;
> +		ida_simple_remove(&rtc_ida, rtc->id);
>  		mutex_unlock(&rtc->ops_lock);
>  		put_device(&rtc->dev);
>  	}

Now I think about it, this shouldn't have been needed?

That put_device() should call rtc_device_release(), which does the
ida_simple_remove().  Isn't that working?

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