On Saturday, January 25, 2014 12:21:06 pm Steve Kargl wrote:
> If I plug my Samsung Intensity II cellphone into a usb port,
> I get an instant panic.  This is 100% reproducible.  I have
> the core and kernel for further debugging.  Dmesg.boot follows
> my sig.
> % kgdb /boot/kernel/kernel /vmcore.0
> Unread portion of the kernel message buffer:
> cd1 at umass-sim1 bus 1 scbus4 target 0 lun 0
> cd1: <SAMSUNG CD-ROM 1.00> Removable CD-ROM SCSI-2 device 
> cd1: Serial Number 000000000002
> cd1: 1.000MB/s transfers
> cd1: cd present [3840000 x 512 byte records]
> cd1: quirks=0x10<10_BYTE_ONLY>
> panic: mutex CAM device lock not owned at /usr/src/sys/cam/cam_periph.c:301
> cpuid = 0
> KDB: enter: panic

scsi@ might work better for this.  It looks like when cdasync() calls 
cam_periph_alloc() it doesn't have its associated xpt_path locked.  All the 
other async xpt callbacks I looked at don't lock the xpt path either.  It 
seems they expect it to be locked by the caller when they are invoked.  It 
seems xpt_async_process_dev() doesn't always lock xpt_lock, but sometimes
locks the device instead:

         * If async for specific device is to be delivered to
         * the wildcard client, take the specific device lock.
         * XXX: We may need a way for client to specify it.
        if ((device->lun_id == CAM_LUN_WILDCARD &&
             path->device->lun_id != CAM_LUN_WILDCARD) ||
            (device->target->target_id == CAM_TARGET_WILDCARD &&
             path->target->target_id != CAM_TARGET_WILDCARD) ||
            (device->target->bus->path_id == CAM_BUS_WILDCARD &&
             path->target->bus->path_id != CAM_BUS_WILDCARD)) {
                relock = 1;
        } else
                relock = 0;

            device->target->bus, device->target, device, async_arg);
        xpt_async_bcast(&device->asyncs, async_code, path, async_arg);

        if (relock) {

Maybe try going up to this frame (16) in your dump and do
'p *device->target'?  However, someone with more CAM knowledge needs to look 
at this to see what is actually broken.

It seems a bit odd that it thinks your phone is a CD player.

John Baldwin
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