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Date:      Wed, 12 Sep 2012 07:49:07 +0200
From:      Hans Petter Selasky <hselasky@c2i.net>
To:        freebsd-usb@freebsd.org
Cc:        mav@freebsd.org, Benjamin Close <Benjamin.Close@clearchain.com>
Subject:   Re: Fwd: usb port issue in 9.1-Prerelease (Possibly Cam related)
Message-ID:  <201209120749.07628.hselasky@c2i.net>
In-Reply-To: <504FDD37.5060407@clearchain.com>
References:  <504DED78.2010203@clearchain.com> <504FDD37.5060407@clearchain.com>

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Hi Alexander,

Looks like some bugs in the refcounting in CAM layer.

--HPS

On Wednesday 12 September 2012 02:54:15 Benjamin Close wrote:
> Sending to -usb as no response from -stable.
> 
> 
> -------- Original Message --------
> Subject: 	usb port issue in 9.1-Prerelease (Possibly Cam related)
> Date: 	Mon, 10 Sep 2012 23:09:04 +0930
> From: 	Benjamin Close <Benjamin.Close@clearchain.com>
> To: 	freebsd-stable@freebsd.org
> 
> 
> 
> Hi Folks,
>      I've facing an intermittent hang with a USB port which seems cam
> related:
> 
> Event's that happen are:
> 
>      o USB modem (HUAWEI E220) plugged into PC
> 
> ugen3.2: <HUA WEI> at usbus3
> u3g0: <3G Modem> on usbus3
> u3g0: Found 3 ports.
> umass0: <USB MASS STORAGE> on usbus3
> umass0:  SCSI over Bulk-Only; quirks = 0x0000
> umass0:6:0:-1: Attached to scbus6
> umass1: <USB MASS STORAGE> on usbus3
> umass1:  SCSI over Bulk-Only; quirks = 0x0000
> umass1:7:1:-1: Attached to scbus7
> cd1 at umass-sim0 bus 0 scbus6 target 0 lun 0
> cd1: <HUAWEI Mass Storage 2.31> Removable CD-ROM SCSI-2 device
> cd1: 1.000MB/s transfers
> cd1: Attempt to query device size failed: NOT READY, Medium not present
> da0 at umass-sim1 bus 1 scbus7 target 0 lun 0
> da0: <HUAWEI SD Storage 2.31> Removable Direct Access SCSI-2 device
> da0: 1.000MB/s transfers
> da0: Attempt to query device size failed: NOT READY, Medium not present
> 
> 
>      o Time Elapses....many packets passed, no da0 or cd1 used.
> 
> 
>      o USB Modem drops off the bus
>         (It does this occasionally as it resets itself)
> 
>      o Causes USB bus to lose devices
> 
> ugen3.2: <HUA WEI> at usbus3 (disconnected)
> u3g0: at uhub3, port 1, addr 2 (disconnected)
> (cd1:umass-sim0:0:0:0): lost device, 1 refs
> (cd1:umass-sim0:0:0:0): removing device entry
> (pass4:umass-sim0:0:0:0): passdevgonecb: devfs entry is gone
> (da0:umass-sim1:1:0:0): lost device - 0 outstanding, 1 refs
> (da0:umass-sim1:1:0:0): removing device entry
> (pass5:umass-sim1:1:0:0): passdevgonecb: devfs entry is gone
> umass0: at uhub3, port 1, addr 2 (disconnected)
> 
> 
> At this point that particular USB port is effectively useless. Plugging
> anything into the ports shows no device showing up.
> 
> Running usbconfig hangs with:
> 
>    PID    TID COMM             TDNAME KSTACK
> 48562 101874 usbconfig        -                mi_switch+0x186
> sleepq_wait+0x42 _sx_xlock_hard+0x426 usbd_enum_lock+0xac
> usb_ref_device+0x21c usb_open+0xc7 devfs_open+0x197 vn_open_cred+0x2ff
> kern_openat+0x20a amd64_syscall+0x540 Xfast_syscall+0xf7
> 
> Controller is:
> 
> uhci0@pci0:0:26:0:      class=0x0c0300 card=0x02091028 chip=0x28348086
> rev=0x02 hdr=0x00
>      vendor     = 'Intel Corporation'
>      device     = '82801H (ICH8 Family) USB UHCI Controller'
>      class      = serial bus
>      subclass   = USB
> uhci1@pci0:0:26:1:      class=0x0c0300 card=0x02091028 chip=0x28358086
> rev=0x02 hdr=0x00
>      vendor     = 'Intel Corporation'
>      device     = '82801H (ICH8 Family) USB UHCI Controller'
>      class      = serial bus
>      subclass   = USB
> ehci0@pci0:0:26:7:      class=0x0c0320 card=0x02091028 chip=0x283a8086
> rev=0x02 hdr=0x00
>      vendor     = 'Intel Corporation'
>      device     = '82801H (ICH8 Family) USB2 EHCI Controller'
>      class      = serial bus
>      subclass   = USB
> 
> It does however seem related to cam as looking at the various threads
> for the usb hub I find:
> 
> (kgdb) bt
> #0  sched_switch (td=0xfffffe0002650000, newtd=0xfffffe000227f000,
> flags=Variable "flags" is not available.
> ) at /usr/src/sys/kern/sched_ule.c:1927
> #1  0xffffffff808f34c6 in mi_switch (flags=260, newtd=0x0) at
> /usr/src/sys/kern/kern_synch.c:485
> #2  0xffffffff8092bfd2 in sleepq_wait (wchan=0xfffffe001ec2a900, pri=92)
> at /usr/src/sys/kern/subr_sleepqueue.c:623
> #3  0xffffffff808f3c69 in _sleep (ident=0xfffffe001ec2a900,
> lock=0xfffffe00371e9210, priority=Variable "priority" is not available.
> ) at /usr/src/sys/kern/kern_synch.c:250
> #4  0xffffffff802bea02 in cam_sim_free (sim=0xfffffe001ec2a900,
> free_devq=1) at /usr/src/sys/cam/cam_sim.c:112
> #5  0xffffffff8074f8ba in umass_detach (dev=Variable "dev" is not
> available. ) at /usr/src/sys/dev/usb/storage/umass.c:2183
> #6  0xffffffff8091a054 in device_detach (dev=0xfffffe001ec2e900) at
> device_if.h:214
> #7  0xffffffff8075c458 in usb_detach_device (udev=0xfffffe0007ce8800,
> iface_index=32 ' ', flag=Variable "flag" is not available.
> ) at /usr/src/sys/dev/usb/usb_device.c:1065
> #8  0xffffffff8075c5f4 in usb_unconfigure (udev=0xfffffe0007ce8800,
> flag=Variable "flag" is not available.
> ) at /usr/src/sys/dev/usb/usb_device.c:455
> #9  0xffffffff8075c88e in usb_free_device (udev=0xfffffe0007ce8800,
> flag=Variable "flag" is not available.
> ) at /usr/src/sys/dev/usb/usb_device.c:2093
> #10 0xffffffff80764e5e in uhub_explore (udev=0xfffffe0007353800) at
> /usr/src/sys/dev/usb/usb_hub.c:358
> #11 0xffffffff8074f536 in usb_bus_explore (pm=Variable "pm" is not
> available.
> ) at /usr/src/sys/dev/usb/controller/usb_controller.c:359
> #12 0xffffffff80769173 in usb_process (arg=Variable "arg" is not available.
> ) at /usr/src/sys/dev/usb/usb_process.c:170
> #13 0xffffffff808bc2df in fork_exit (callout=0xffffffff807690a0
> <usb_process>, arg=0xffffff80007c0e88, frame=0xffffff804743cc40) at
> /usr/src/sys/kern/kern_fork.c:992
> #14 0xffffffff80bc216e in fork_trampoline () at
> /usr/src/sys/amd64/amd64/exception.S:602
> 
> 
> From:   cam_sim_free(struct cam_sim *sim, int free_devq)
> 
> (kgdb) l
> 107     {
> 108             int error;
> 109
> 110             sim->refcount--;
> 111             if (sim->refcount > 0) {
> 
> 112                     error = msleep(sim, sim->mtx, PRIBIO, "simfree",
> 0);
> 
> 113                     KASSERT(error == 0, ("invalid error value for
> msleep(9)"));
> 114             }
> 115
> 116             KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
> 
> 
> It almost appears as if the cam layer is trying to finalise a write of
> some sort but the physical device has already gone.
> 
> (kgdb) p sim->refcount
> $1 = 1
> 
> Not sure why refcount is still ==1.
> 
> The same device in a box running 9.0-Stable (as of about 3 months ago)
> with a ICH9 controller works as expected.
> 
> Any suggestions?
> 
> Cheers,
>      Benjamin
> 
> 
> 
> 
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