From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752287Ab2LSHqE (ORCPT ); Wed, 19 Dec 2012 02:46:04 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:37986 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751544Ab2LSHp4 (ORCPT ); Wed, 19 Dec 2012 02:45:56 -0500 Date: Tue, 18 Dec 2012 23:45:43 -0800 From: Andrew Morton To: Alexander Holler Cc: Vincent Palatin , rtc-linux@googlegroups.com, Alessandro Zummo , linux-kernel@vger.kernel.org Subject: Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver Message-Id: <20121218234543.786a2211.akpm@linux-foundation.org> In-Reply-To: <50D16EA3.8040803@ahsoftware.de> References: <1343951605-25722-1-git-send-email-vpalatin@chromium.org> <20121218164659.a3d3655a.akpm@linux-foundation.org> <50D16EA3.8040803@ahsoftware.de> X-Mailer: Sylpheed 2.7.1 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Dec 2012 08:37:07 +0100 Alexander Holler wrote: > Am 19.12.2012 01:46, schrieb Andrew Morton: > > On Thu, 2 Aug 2012 16:53:25 -0700 > > Vincent Palatin 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 > >> --- > >> 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? > > It is, see the mini-thread, patch and my comment here: > > https://lkml.org/lkml/2012/12/6/152 > > Maybe it would be better to move the ida_simple_remove from the > rtc_device_release to rt_device_unregister as I've hinted in the above > comment. That would make it easier to spot the ida_simple_remove(). I'm all confused. Lothar's patch simply reverts Vincent's patch. And that appears to be the correct thing to so, as the ida_simple_remove() in rtc_device_release() should be sufficient. But apparently that doesn't work, because Vincent was seeing the RTC ID's increment rather than getting reused. Is it the case that rtc_device_release() is not being called sometimes? If so, under what circumstances?