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Message-Id: <20121219143725.3f49598c.akpm@linux-foundation.org> Date: Wed, 19 Dec 2012 14:37:25 -0800 From: Andrew Morton <akpm@...ux-foundation.org> To: Alexander Holler <holler@...oftware.de> Cc: Vincent Palatin <vpalatin@...omium.org>, rtc-linux@...glegroups.com, Alessandro Zummo <a.zummo@...ertech.it>, linux-kernel@...r.kernel.org, Lothar Waßmann <LW@...O-electronics.de> Subject: Re: [rtc-linux] [PATCH] rtc: recycle id when unloading a rtc driver On Wed, 19 Dec 2012 09:55:02 +0100 Alexander Holler <holler@...oftware.de> wrote: > Am 19.12.2012 09:27, schrieb Andrew Morton: > > On Wed, 19 Dec 2012 08:55:57 +0100 Alexander Holler <holler@...oftware.de> 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 <akpm@...ux-foundation.org> Subject: revert "rtc: recycle id when unloading a rtc driver" Revert commit 2830a6d20139df2198d63235df7957712adb28e5 Author: Vincent Palatin <vpalatin@...omium.org> 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 <LW@...O-electronics.de> Acked-by: Alexander Holler <holler@...oftware.de> Cc: Vincent Palatin <vpalatin@...omium.org> Cc: <stable@...r.kernel.org> [3.7.x] Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> --- 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); } _ -- 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/
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