Instant panic CAM or USB subsystem

[John Baldwin]

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)) {
		mtx_unlock(&device->device_mtx);
		xpt_path_lock(path);
		relock = 1;
	} else
		relock = 0;

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

	if (relock) {
		xpt_path_unlock(path);
		mtx_lock(&device->device_mtx);
	}

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