Re: USB serial regression 2.6.31.1 -> 2.6.31.2

[Alan Stern]

On Sun, 11 Oct 2009, Benjamin Herrenschmidt wrote:

> On Sun, 2009-10-11 at 08:20 +1100, Benjamin Herrenschmidt wrote:
> 
> > Yes, that works, you can see the ttyUSBx ports showing up. It looks like
> > it may just be the resets coming from usb-storage that are breaking
> > things.
> 
> Ok so I did a quick hack to usb-storage, basically put the block that
> tests for the response size and sets USB_FL_SANE_SENSE into an #if 0 :

> Now, the result in the dmesg log is :
> 
> Oct 11 09:04:05 pasglop kernel: [   52.916100] usb 4-1: new full speed USB device using uhci_hcd and address 2
> Oct 11 09:04:05 pasglop kernel: [   53.076402] usb 4-1: configuration #1 chosen from 1 choice
> Oct 11 09:04:06 pasglop kernel: [   53.104090] Initializing USB Mass Storage driver...
> Oct 11 09:04:06 pasglop kernel: [   53.105405] scsi2 : SCSI emulation for USB Mass Storage devices
> Oct 11 09:04:06 pasglop kernel: [   53.105585] usbcore: registered new interface driver usb-storage
> Oct 11 09:04:06 pasglop kernel: [   53.105589] USB Mass Storage support registered.
> Oct 11 09:04:06 pasglop kernel: [   53.107164] usb-storage: device found at 2
> Oct 11 09:04:06 pasglop kernel: [   53.107167] usb-storage: waiting for device to settle before scanning
> Oct 11 09:04:06 pasglop kernel: [   53.224104] usb 4-1: USB disconnect, address 2
> Oct 11 09:04:06 pasglop kernel: [   53.960100] usb 4-1: new full speed USB device using uhci_hcd and address 3
> Oct 11 09:04:11 pasglop kernel: [   54.121941] usb 4-1: configuration #1 chosen from 1 choice
> Oct 11 09:04:11 pasglop kernel: [   54.140861] scsi6 : SCSI emulation for USB Mass Storage devices
> Oct 11 09:04:11 pasglop kernel: [   54.143007] usb-storage: device found at 3
> Oct 11 09:04:11 pasglop kernel: [   54.143010] usb-storage: waiting for device to settle before scanning
> Oct 11 09:04:11 pasglop kernel: [   59.141422] usb-storage: device scan complete
> Oct 11 09:04:11 pasglop kernel: [   59.144370] scsi 6:0:0:0: CD-ROM            HUAWEI   Mass Storage     2.31 PQ: 0 ANSI: 2
> Oct 11 09:04:11 pasglop kernel: [   59.147379] scsi 6:0:0:1: Direct-Access     HUAWEI   SD Storage       2.31 PQ: 0 ANSI: 2
> Oct 11 09:04:11 pasglop kernel: [   59.169383] sr1: scsi-1 drive
> 
> At which point nothing happens for a while (and no serial stuff shows up).
> 
> If I yank the device, I then see:
> 
> Oct 11 09:05:28 pasglop kernel: [   59.169494] sr 6:0:0:0: Attached scsi CD-ROM sr1
> Oct 11 09:05:28 pasglop kernel: [   59.169563] sr 6:0:0:0: Attached scsi generic sg2 type 5
> Oct 11 09:05:28 pasglop kernel: [   59.169668] sd 6:0:0:1: Attached scsi generic sg3 type 0
> Oct 11 09:05:28 pasglop kernel: [   59.227809] sd 6:0:0:1: [sdb] Attached SCSI removable disk
> Oct 11 09:05:28 pasglop kernel: [   71.048322] ISO 9660 Extensions: Microsoft Joliet Level 1
> Oct 11 09:05:28 pasglop kernel: [   71.057316] ISOFS: changing to secondary root
> Oct 11 09:05:28 pasglop kernel: [  128.369159] usb 4-1: USB disconnect, address 3
> Oct 11 09:05:28 pasglop kernel: [  128.429675] scsi 6:0:0:0: rejecting I/O to dead device

The printk timestamps indicate that the first four lines above happened
before you unplugged the device.  Maybe the first six.  But evidently
the syslogd process was blocked.

> 
> However, if I put it back in later on ... it works. The storage shows up
> and the modem too.
> 
> Weird. I'll have to reboot to try to reproduce with usbmon logging.

You might have to get a stack trace (Alt-SysRq-T) as well.  It sounds 
like something important got hung up somewhere.  Perhaps the usb-serial 
modules couldn't be loaded for that reason.

Alan Stern

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