On 07/25/2014 06:20 PM, Frank Schäfer wrote: > Hi Hans, > > I'm getting the following warnings with the em28xx driver on streaming stop: > > [ 7597.346168] WARNING: CPU: 1 PID: 3730 at > drivers/media/v4l2-core/videobuf2-core.c:2126 > __vb2_queue_cancel+0xf5/0x150 [videobuf2_core]() > [ 7597.346171] Modules linked in: em28xx_rc snd_usb_audio ov2640 > soc_camera soc_mediabus em28xx_v4l videobuf2_core videobuf2_vmalloc > videobuf2_memops snd_usbmidi_lib snd_rawmidi em28xx xt_pkttype xt_LOG > xt_limit bnep af_packet bluetooth ip6t_REJECT xt_tcpudp > nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_raw ipt_REJECT iptable_raw > xt_CT iptable_filter ip6table_mangle nf_conntrack_netbios_ns > nf_conntrack_broadcast nf_conntrack_ipv4 nf_defrag_ipv4 ip_tables > xt_conntrack nf_conntrack ip6table_filter ip6_tables x_tables > rc_hauppauge ir_kbd_i2c arc4 tuner_simple tuner_types rtl8187 mac80211 > tda9887 fuse tda8290 snd_hda_codec_analog tuner snd_hda_codec_hdmi > snd_hda_codec_generic sr_mod cdrom snd_hda_intel snd_hda_controller > snd_hda_codec msp3400 snd_hwdep cfg80211 bttv snd_pcm v4l2_common > snd_seq ppdev powernow_k8 > [ 7597.346230] snd_timer snd_seq_device pcspkr videodev serio_raw snd > firewire_ohci firewire_core k8temp rfkill eeprom_93cx6 i2c_nforce2 > usb_storage videobuf_dma_sg videobuf_core btcx_risc pata_jmicron rc_core > usblp soundcore forcedeth crc_itu_t tveeprom ata_generic floppy sata_nv > pata_amd asus_atk0110 parport_pc parport button sg dm_mod autofs4 radeon > ttm drm_kms_helper drm fan thermal processor thermal_sys i2c_algo_bit > scsi_dh_hp_sw scsi_dh_emc scsi_dh_rdac scsi_dh_alua scsi_dh > [ 7597.346268] CPU: 1 PID: 3730 Comm: qv4l2 Tainted: G W > 3.16.0-rc6-0.1-desktop+ #18 > [ 7597.346271] Hardware name: System manufacturer System Product Name [...] > [ 7597.346273] 00000000 00000000 e09d9d3c c0780b62 00000000 e09d9d6c > c0243359 c091deec > [ 7597.346279] 00000001 00000e92 f870a4a4 0000084e f87054e5 f87054e5 > e6905040 e2f61640 > [ 7597.346285] ef85f4c8 e09d9d7c c02433ed 00000009 00000000 e09d9d94 > f87054e5 e2ef6550 > [ 7597.346290] Call Trace: > [ 7597.346300] [<c0780b62>] dump_stack+0x48/0x69 > [ 7597.346305] [<c0243359>] warn_slowpath_common+0x79/0x90 > [ 7597.346312] [<f87054e5>] ? __vb2_queue_cancel+0xf5/0x150 > [videobuf2_core] > [ 7597.346318] [<f87054e5>] ? __vb2_queue_cancel+0xf5/0x150 > [videobuf2_core] > [ 7597.346322] [<c02433ed>] warn_slowpath_null+0x1d/0x20 > [ 7597.346327] [<f87054e5>] __vb2_queue_cancel+0xf5/0x150 [videobuf2_core] > [ 7597.346333] [<f8706b35>] vb2_internal_streamoff+0x35/0x90 > [videobuf2_core] > [ 7597.346338] [<c04b7cbb>] ? _copy_from_user+0x3b/0x50 > [ 7597.346344] [<f8706bc5>] vb2_streamoff+0x35/0x60 [videobuf2_core] > [ 7597.346350] [<c0699433>] ? __sys_recvmsg+0x43/0x70 > [ 7597.346356] [<f8706c27>] vb2_ioctl_streamoff+0x37/0x40 [videobuf2_core] > [ 7597.346371] [<f7c56805>] v4l_streamoff+0x15/0x20 [videodev] > [ 7597.346382] [<f7c5962c>] __video_do_ioctl+0x1fc/0x280 [videodev] > [ 7597.346394] [<f7c5908e>] video_usercopy+0x1ce/0x550 [videodev] > [ 7597.346399] [<c038aac7>] ? fsnotify+0x1e7/0x2b0 > [ 7597.346410] [<f7c59422>] video_ioctl2+0x12/0x20 [videodev] > [ 7597.346421] [<f7c59430>] ? video_ioctl2+0x20/0x20 [videodev] > [ 7597.346430] [<f7c55615>] v4l2_ioctl+0xe5/0x120 [videodev] > [ 7597.346439] [<f7c55530>] ? v4l2_open+0xf0/0xf0 [videodev] > [ 7597.346443] [<c03668e2>] do_vfs_ioctl+0x2e2/0x4d0 > [ 7597.346449] [<c0356a3c>] ? vfs_write+0x13c/0x1c0 > [ 7597.346452] [<c03575df>] ? vfs_writev+0x2f/0x50 > [ 7597.346455] [<c0366b28>] SyS_ioctl+0x58/0x80 > [ 7597.346460] [<c07870ec>] sysenter_do_call+0x12/0x16 > [ 7597.346463] ---[ end trace 16421a251cba8f63 ]--- > > > There have been quite a few vb2 changes recently. > Any idea what's wrong ? Could you take a look at this ? OK, I looked at it: the problem is in get_next_buf() and finish_field_prepare_next(). In get_next_buf() the driver gets a buffer from the active list and deletes it from that list. In finish_field_prepare_next() that buffer is given back to vb2 via finish_buffer(). But if you stop streaming and em28xx_stop_streaming() is called, then that buffer that is being processed isn't part of the active list anymore and so it is never given back. em28xx_stop_streaming() should give that buffer back as well, and that will keep everything in balance. The easiest solution seems to be to move the list_del() call from get_next_buf() to finish_buffer(). It seemed to work in a quick test, but I haven't looked at vbi support or corner cases. I leave that to you :-) Regards, Hans -- 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
