From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751895Ab2LSWhe (ORCPT ); Wed, 19 Dec 2012 17:37:34 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:44506 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751653Ab2LSWh1 (ORCPT ); Wed, 19 Dec 2012 17:37:27 -0500 Date: Wed, 19 Dec 2012 14:37:25 -0800 From: Andrew Morton To: Alexander Holler Cc: Vincent Palatin , rtc-linux@googlegroups.com, Alessandro Zummo , linux-kernel@vger.kernel.org, Lothar =?ISO-8859-1?Q?Wa=DFmann?= Subject: Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver Message-Id: <20121219143725.3f49598c.akpm@linux-foundation.org> In-Reply-To: <50D180E6.3010305@ahsoftware.de> References: <1343951605-25722-1-git-send-email-vpalatin@chromium.org> <20121218164659.a3d3655a.akpm@linux-foundation.org> <50D16EA3.8040803@ahsoftware.de> <20121218234543.786a2211.akpm@linux-foundation.org> <50D1730D.7010108@ahsoftware.de> <20121219002722.87438a08.akpm@linux-foundation.org> <50D180E6.3010305@ahsoftware.de> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-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 09:55:02 +0100 Alexander Holler wrote: > Am 19.12.2012 09:27, schrieb Andrew Morton: > > On Wed, 19 Dec 2012 08:55:57 +0100 Alexander Holler wrote: > > > >>> > >>> 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? > >> > >> Maybe something (sysfs or whatever) still has a reference to it. Vincent > >> should check that. > >> > >> But I'm sure the ID will be recycled with that put_device() in > >> unregister because I've got the same warning as Lothar did when > >> (porperly) removing an RTC (with kernel 3.7). > > > > If, as appears to be the case, rtc_device_release() is not being called > > then we're also leaking memory. So yes please, it would be good if > > someone who can reproduce the IDs-dont-decrease problem could dive in > > and work out why ->release() isn't begin called. > > Unlikely, as I've worked hard to get one of the first drivers for > pluggable RTCs into the kernel. ;) > I think every sane kernel has them statically linked in and it's likely > a problem of the RTC-driver Vincent experienced that with. > I think I'll do this: From: Andrew Morton Subject: revert "rtc: recycle id when unloading a rtc driver" Revert commit 2830a6d20139df2198d63235df7957712adb28e5 Author: Vincent Palatin Date: Thu Oct 4 17:13:52 2012 -0700 rtc: recycle id when unloading a rtc driver We already perform the ida_simple_remove() in rtc_device_release(), which is an appropriate place. 2830a6d20 ("rtc: recycle id when unloading a rtc driver") caused the kernel to emit ida_remove called for id=0 which is not allocated. warnings when rtc_device_release() tries to release an alread-released ID. Let's restore things to their previous state and then work out why Vincent's kernel wasn't calling rtc_device_release() - presumably a bug in a specific sub-driver. Reported-by: Lothar Wa_mann Acked-by: Alexander Holler Cc: Vincent Palatin Cc: [3.7.x] Signed-off-by: Andrew Morton --- drivers/rtc/class.c | 1 - 1 file changed, 1 deletion(-) diff -puN drivers/rtc/class.c~revert-rtc-recycle-id-when-unloading-a-rtc-driver drivers/rtc/class.c --- a/drivers/rtc/class.c~revert-rtc-recycle-id-when-unloading-a-rtc-driver +++ a/drivers/rtc/class.c @@ -244,7 +244,6 @@ void rtc_device_unregister(struct rtc_de 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); } _