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Date: Wed, 19 Jan 2011 12:47:02 +0100 (CET) From: Rune Saetre <rune.saetre@...omar.com> To: linux-kernel@...r.kernel.org cc: Patrik Jakobsson <patrik.r.jakobsson@...il.com>, Hans Verkuil <hverkuil@...all.nl>, Rune Saetre <rune.saetre@...omar.com>, linux-media@...r.kernel.org Subject: Re: PROBLEM: kernel BUG at drivers/media/video/em28xx/em28xx-video.c:891 Hi Yes. I will try it out and post a message as soon as I have some experience with it. Regards Rune -- We are proud to present our new web-pages at www.aptomar.com Do not miss our video-window to the world; aptotube Rune Sætre <rune.saetre@...omar.com> aptomar as Tel. (+47) 40 00 34 03 Mob. (+47) 93 43 42 85 Fax (+47) 73 51 00 84 www.aptomar.com On Wed, 19 Jan 2011, Patrik Jakobsson wrote: > On 01/18/2011 05:30 PM, Hans Verkuil wrote: >> On Tuesday, January 18, 2011 17:14:03 Patrik Jakobsson wrote: >>> Hello Rune >>> >>> I'm trying to learn more about the linux kernel so I figured helping >>> with bugs is a good way to get started. >>> >>> On 01/18/2011 02:20 AM, Rune Saetre wrote: >>>> Hi >>>> >>>> The crash is not as consistent as I first believed. I have managed to >>>> stop and start capturing several (but not many) times without the >>>> driver crashing now. >>>> >>> To me it seems that the resource locking (functions res_get, res_check, >>> res_locked and res_free) is subject to race condition. >>> >>> I looked at older versions of the code and found that there used to be >>> locks around some of these pieces. It was removed in commit: >>> >>> 0499a5aa777f8e56e46df362f0bb9d9d116186f9 - V4L/DVB: em28xx: remove BKL >>> >>> Other V4L drivers use pretty much the same code (res_get, res_free, >>> etc.) for resource locking but still have the mutex_lock/unlock around >>> it. Does anyone know why this was removed? >> Because now the video4linux core does the locking. >> >> Anyway, I'm pretty sure this is the bug that was fixed here: >> >> http://www.mail-archive.com/linuxtv-commits@linuxtv.org/msg09413.html >> >> This fix will be in 2.6.38. >> >> The change in the locking mechanism had nothing to do this particular bug. >> It was just incorrect administration of resources. >> >> Regards, >> >> Hans >> > Thanks for the explanation. I see now how the V4L core locks around the > ioctls. The member unlocked_ioctl of struct v4l2_file_operations confused me > a little. Maybe serialized_ioctl would be a better name? Not a big issue > though. > > Hopefully the patch fixes your problem Rune. > > Thanks > Patrik Jakobsson > >>> Thanks >>> Patrik Jakobsson >>>> The trace logs also differ slightly. Here is the last one: >>>> >>>> Jan 18 02:12:08 mate kernel: [ 117.219326] ------------[ cut here >>>> ]------------ >>>> Jan 18 02:12:08 mate kernel: [ 117.219412] kernel BUG at >>>> drivers/media/video/em28xx/em28xx-video.c:891! >>>> Jan 18 02:12:08 mate kernel: [ 117.219507] invalid opcode: 0000 [#1] >>>> PREEMPT SMP Jan 18 02:12:08 mate kernel: [ 117.219597] last sysfs >>>> file: /sys/devices/virtual/block/dm-8/stat >>>> Jan 18 02:12:08 mate kernel: [ 117.219681] CPU 1 Jan 18 02:12:08 mate >>>> kernel: [ 117.219714] Modules linked in: acpi_cpufreq mperf >>>> cpufreq_powersave cpufreq_stats cpufreq_userspace cpufreq_conservative >>>> ppdev lp nfsd lockd nfs_acl auth_rpcgss sunrpc exportfs binfmt_misc >>>> fuse dummy bridge stp ext2 mbcache coretemp kvm_intel kvm loop >>>> firewire_sbp2 tuner snd_hda_codec_realtek arc4 snd_hda_intel >>>> snd_usb_audio snd_hda_codec ecb snd_seq_dummy snd_pcm_oss >>>> snd_mixer_oss saa7115 snd_pcm ir_lirc_codec lirc_dev ir_sony_decoder >>>> snd_hwdep snd_usbmidi_lib em28xx ir_jvc_decoder ir_rc6_decoder >>>> snd_seq_oss snd_seq_midi snd_rawmidi r8169 ir_rc5_decoder mii >>>> ir_nec_decoder snd_seq_midi_event i915 v4l2_common iwlagn iwlcore >>>> snd_seq ir_core drm_kms_helper drm videobuf_vmalloc snd_timer >>>> snd_seq_device videobuf_core pcmcia joydev mac80211 uvcvideo videodev >>>> v4l1_compat v4l2_compat_ioctl32 tveeprom cfg80211 rfkill i2c_i801 >>>> i2c_algo_bit tpm_tis tpm yenta_socket snd intel_agp shpchp pci_hotplug >>>> video output pcmcia_rsrc wmi pcmcia_core soundcore snd_page_alloc >>>> parport_pc parport i2c_cor >>>> Jan 18 02:12:08 mate kernel: irda tpm_bios intel_gtt pcspkr crc_ccitt >>>> psmouse evdev serio_raw container processor battery ac button reiserfs >>>> dm_mod raid10 raid456 async_raid6_recov async_pq raid6_pq async_xor >>>> xor async_memcpy async_tx raid1 raid0 multipath linear md_mod >>>> ide_cd_mod cdrom sd_mod ata_generic pata_acpi ata_piix crc_t10dif >>>> ide_pci_generic ahci libahci sdhci_pci firewire_ohci sdhci libata >>>> scsi_mod piix ide_core firewire_core mmc_core uhci_hcd tg3 thermal >>>> crc_itu_t thermal_sys ehci_hcd [last unloaded: scsi_wait_scan] >>>> Jan 18 02:12:08 mate kernel: [ 117.220091] Jan 18 02:12:08 mate >>>> kernel: [ 117.220091] Pid: 3154, comm: camera_factory_ Not tainted >>>> 2.6.37-rst #1 Victoria /TravelMate 6292 Jan 18 02:12:08 mate >>>> kernel: [ 117.220091] RIP: 0010:[<ffffffffa05a37f4>] >>>> [<ffffffffa05a37f4>] res_free+0x14/0x49 [em28xx] >>>> Jan 18 02:12:08 mate kernel: [ 117.220091] RSP: >>>> 0018:ffff8800794a1c48 EFLAGS: 00010297 >>>> Jan 18 02:12:08 mate kernel: [ 117.220091] RAX: 0000000000000001 RBX: >>>> ffff88007b94dc00 RCX: 0000000000000000 >>>> Jan 18 02:12:08 mate kernel: [ 117.220091] RDX: 0000000000000000 RSI: >>>> ffff8800378e7000 RDI: ffff88007b94dc00 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] RBP: ffff8800378e7000 R08: >>>> 0000000000000001 R09: 0000000000000c52 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] R10: 0000000000000000 R11: >>>> 0000000000000246 R12: 0000000000000000 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] R13: ffffffffa05ab920 R14: >>>> ffff88006dd123c0 R15: ffff88007b94dc00 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] FS: >>>> 00007f37105bb820(0000) GS:ffff88007f500000(0000) knlGS:0000000000000000 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] CS: 0010 DS: 0000 ES: >>>> 0000 CR0: 0000000080050033 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] CR2: 000000000378b248 CR3: >>>> 000000007a079000 CR4: 00000000000006e0 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] DR0: 0000000000000000 DR1: >>>> 0000000000000000 DR2: 0000000000000000 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] DR3: 0000000000000000 DR6: >>>> 00000000ffff0ff0 DR7: 0000000000000400 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] Process camera_factory_ >>>> (pid: 3154, threadinfo ffff8800794a0000, task ffff880071f6d820) >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] Stack: >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] ffff8800378e7000 >>>> ffffffffa05a46b9 ffff88007a2fd040 ffffffff81042cf3 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] 0000000000000001 >>>> ffffffff00000001 ffffffff8103dadb 0000000000000001 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] ffff88007ba3e400 >>>> ffffffffa03302ff 00000000000135c0 00000000000135c0 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] Call Trace: >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffffa05a46b9>] ? >>>> vidioc_streamoff+0xa6/0xb6 [em28xx] >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81042cf3>] ? >>>> get_parent_ip+0x9/0x1b >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff8103dadb>] ? >>>> need_resched+0x1a/0x23 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffffa03302ff>] ? >>>> __video_do_ioctl+0x12e2/0x33a0 [videodev] >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff8103a5fe>] ? >>>> __wake_up_common+0x41/0x78 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff8103da1b>] ? >>>> __wake_up+0x35/0x46 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81042cf3>] ? >>>> get_parent_ip+0x9/0x1b >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81044d80>] ? >>>> add_preempt_count+0x9e/0xa0 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff8132935c>] ? >>>> _raw_spin_lock_irqsave+0x40/0x61 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffffa03326f4>] ? >>>> video_ioctl2+0x2ad/0x35d [videodev] >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81042cf3>] ? >>>> get_parent_ip+0x9/0x1b >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffffa032e342>] ? >>>> v4l2_ioctl+0x74/0x113 [videodev] >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81106f51>] ? >>>> do_vfs_ioctl+0x418/0x465 >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81106fda>] ? >>>> sys_ioctl+0x3c/0x5e >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] [<ffffffff81009c52>] ? >>>> system_call_fastpath+0x16/0x1b >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] Code: 03 4c 39 e3 0f 18 08 >>>> 75 d4 31 c0 eb 05 b8 ea ff ff ff 5b 5d 41 5c c3 48 83 ec 08 8b 57 0c >>>> 89 f0 89 c1 48 8b 37 21 d1 39 c1 74 04<0f> 0b eb fe 89 c8 f7 d0 21 c2 >>>> 89 57 0c 21 86 d0 09 00 00 83 3d Jan 18 02:12:09 mate kernel: [ >>>> 117.220091] RIP [<ffffffffa05a37f4>] res_free+0x14/0x49 [em28xx] >>>> Jan 18 02:12:09 mate kernel: [ 117.220091] RSP<ffff8800794a1c48> >>>> Jan 18 02:12:09 mate kernel: [ 117.264998] ---[ end trace >>>> 6d6576ecd99356c8 ]--- >>>> >>>> I hope this helps. >>>> >>>> Regards >>>> Rune >>>> >>>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-media" in >>> the body of a message to majordomo@...r.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> > >
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