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 > 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Hans Verkuil - video4linux developer - sponsored by Cisco -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
