On Mon, 7 Nov 2016 15:31:11 +0100, Greg KH wrote: > On Mon, Nov 07, 2016 at 08:06:41AM -0500, Dennis New wrote: > > So, I have a USB audio dongle (currently using ohci, but the same > > would probably happen with ehci), and if I stupidly decide to > > unplug it while I'm streaming audio (alsa) to it, mplayer (for > > example) first freezes ... and if I quit mplayer immediately, > > things are fine ... but if I try to continue playing (by > > unpausing/seeking), mplayer goes into an infinite loop of errors > > trying to write to the (alsa?) audio device, but more importantly, > > my kernel's (4.8.6) entire usb system seems to break ... I can't > > even properly load my ehci_pci kernel drivers (it is actually able > > to load them, but they can't be unloaded... they seem to get > > immediately hung too... even though the dongle was using ohci at > > the time) ... my alsa sound is also broken/hung so I no longer get > > audio ... I'm forced to reboot (and even here it can't power off, I > > have to force it with the PrtSc buttons). > > If you are able to get any kind of kernel log message when you remove > the device, that would help out a lot in trying to track this issue > down. Without that, it's going to be almost impossible, sorry... Hrm. I think the problem was with alsa-lib-1.0.29'ish. Upgrading to alsa-lib-1.1.2 fixed the problem. With the older alsa-lib, after abruptly unplugging my usb audio device, although mplayer does freeze, if I try to resume it, "it" (alsa?) gets into an endless loop: ... [AO_ALSA] Trying to reset soundcard. [AO_ALSA] Write error: No such device [AO_ALSA] Trying to reset soundcard. [AO_ALSA] Write error: No such device [AO_ALSA] Trying to reset soundcard. [AO_ALSA] Write error: No such device [AO_ALSA] Trying to reset soundcard. With the newer alsa-lib, mplayer gracefully instead simply says: [AO_ALSA] pcm prepare error: File descriptor in bad state With the older alsa-lib, mplayer, and perhaps other stuff were stuck in a hung/zombie state, and I guess this was somehow causing the snd-usb-audio kernel driver and/or usb stack to get hung as well? It was also preventing my machine from powering off normally. # ps -ef | grep mplayer denn 25421 1 0 21:35 ? 00:00:01 [mplayer] denn 25422 25421 0 21:35 ? 00:00:00 [mplayer] <defunct> # lsof | grep mplayer mplayer 25421 denn cwd unknown /proc/25421/cwd (readlink: No such file or directory) mplayer 25421 denn rtd unknown /proc/25421/root (readlink: No such file or directory) mplayer 25421 denn txt unknown /proc/25421/exe (readlink: No such file or directory) Anywho, things work now. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
