Re: PROBLEM: kernel BUG at drivers/media/video/em28xx/em28xx-video.c:891

[Rune Saetre]

Hi

The STREAMOFF issue has not appeared after having tested with kernel 
version 2.6.38-rc2 for a while. I am happy :-)

Regards
Rune

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Rune Sætre <rune.saetre@xxxxxxxxxxx>
aptomar as

www.aptomar.com


On Wed, 19 Jan 2011, Rune Saetre wrote:

> 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@xxxxxxxxxxx>
> aptomar as
>
> 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@xxxxxxxxxxx/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
> > > > --
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