Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759863AbaLLGdW (ORCPT ); Fri, 12 Dec 2014 01:33:22 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51884 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759292AbaLLGQ6 (ORCPT ); Fri, 12 Dec 2014 01:16:58 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" Date: Fri, 12 Dec 2014 06:14:25 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 113/164] ALSA: usb-audio: Fix device_del() sysfs warnings at disconnect In-Reply-To: X-SA-Exim-Connect-IP: 2001:470:1f08:1539:c97:8151:cc89:c28d X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.65-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 0725dda207e95ff25f1aa01432250323e0ec49d6 upstream. Some USB-audio devices show weird sysfs warnings at disconnecting the devices, e.g. usb 1-3: USB disconnect, device number 3 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 973 at fs/sysfs/group.c:216 device_del+0x39/0x180() sysfs group ffffffff8183df40 not found for kobject 'midiC1D0' Call Trace: [] ? dump_stack+0x49/0x71 [] ? warn_slowpath_common+0x82/0xb0 [] ? warn_slowpath_fmt+0x45/0x50 [] ? device_del+0x39/0x180 [] ? device_unregister+0x9/0x20 [] ? device_destroy+0x34/0x40 [] ? snd_unregister_device+0x7f/0xd0 [snd] [] ? snd_rawmidi_dev_disconnect+0xce/0x100 [snd_rawmidi] [] ? snd_device_disconnect+0x62/0x90 [snd] [] ? snd_device_disconnect_all+0x3c/0x60 [snd] [] ? snd_card_disconnect+0x124/0x1a0 [snd] [] ? usb_audio_disconnect+0x88/0x1c0 [snd_usb_audio] [] ? usb_unbind_interface+0x5e/0x1b0 [usbcore] [] ? __device_release_driver+0x79/0xf0 [] ? device_release_driver+0x25/0x40 [] ? bus_remove_device+0xf1/0x130 [] ? device_del+0x109/0x180 [] ? usb_disable_device+0x95/0x1f0 [usbcore] [] ? usb_disconnect+0x8f/0x190 [usbcore] [] ? hub_thread+0x539/0x13a0 [usbcore] [] ? sched_clock_local+0x15/0x80 [] ? sched_clock_cpu+0xb8/0xd0 [] ? bit_waitqueue+0xb0/0xb0 [] ? usb_port_resume+0x430/0x430 [usbcore] [] ? usb_port_resume+0x430/0x430 [usbcore] [] ? kthread+0xce/0xf0 [] ? kthread_create_on_node+0x1c0/0x1c0 [] ? ret_from_fork+0x7c/0xb0 [] ? kthread_create_on_node+0x1c0/0x1c0 ---[ end trace 40b1928d1136b91e ]--- This comes from the fact that usb-audio driver may receive the disconnect callback multiple times, per each usb interface. When a device has both audio and midi interfaces, it gets called twice, and currently the driver tries to release resources at the last call. At this point, the first parent interface has been already deleted, thus deleting a child of the first parent hits such a warning. For fixing this problem, we need to call snd_card_disconnect() and cancel pending operations at the very first disconnect while the release of the whole objects waits until the last disconnect call. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=80931 Reported-and-tested-by: Tomas Gayoso Reported-and-tested-by: Chris J Arges Signed-off-by: Takashi Iwai [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- sound/usb/card.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -568,18 +568,19 @@ static void snd_usb_audio_disconnect(str { struct snd_card *card; struct list_head *p; + bool was_shutdown; if (chip == (void *)-1L) return; card = chip->card; down_write(&chip->shutdown_rwsem); + was_shutdown = chip->shutdown; chip->shutdown = 1; up_write(&chip->shutdown_rwsem); mutex_lock(®ister_mutex); - chip->num_interfaces--; - if (chip->num_interfaces <= 0) { + if (!was_shutdown) { snd_card_disconnect(card); /* release the pcm resources */ list_for_each(p, &chip->pcm_list) { @@ -593,6 +594,10 @@ static void snd_usb_audio_disconnect(str list_for_each(p, &chip->mixer_list) { snd_usb_mixer_disconnect(p); } + } + + chip->num_interfaces--; + if (chip->num_interfaces <= 0) { usb_chip[chip->index] = NULL; mutex_unlock(®ister_mutex); snd_card_free_when_closed(card); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/