Commit Graph

303 Commits

Author SHA1 Message Date
Mark Murray
d1b06863fb Huge cleanup of random(4) code.
* GENERAL
- Update copyright.
- Make kernel options for RANDOM_YARROW and RANDOM_DUMMY. Set
  neither to ON, which means we want Fortuna
- If there is no 'device random' in the kernel, there will be NO
  random(4) device in the kernel, and the KERN_ARND sysctl will
  return nothing. With RANDOM_DUMMY there will be a random(4) that
  always blocks.
- Repair kern.arandom (KERN_ARND sysctl). The old version went
  through arc4random(9) and was a bit weird.
- Adjust arc4random stirring a bit - the existing code looks a little
  suspect.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Redo read_random(9) so as to duplicate random(4)'s read internals.
  This makes it a first-class citizen rather than a hack.
- Move stuff out of locked regions when it does not need to be
  there.
- Trim RANDOM_DEBUG printfs. Some are excess to requirement, some
  behind boot verbose.
- Use SYSINIT to sequence the startup.
- Fix init/deinit sysctl stuff.
- Make relevant sysctls also tunables.
- Add different harvesting "styles" to allow for different requirements
  (direct, queue, fast).
- Add harvesting of FFS atime events. This needs to be checked for
  weighing down the FS code.
- Add harvesting of slab allocator events. This needs to be checked for
  weighing down the allocator code.
- Fix the random(9) manpage.
- Loadable modules are not present for now. These will be re-engineered
  when the dust settles.
- Use macros for locks.
- Fix comments.

* src/share/man/...
- Update the man pages.

* src/etc/...
- The startup/shutdown work is done in D2924.

* src/UPDATING
- Add UPDATING announcement.

* src/sys/dev/random/build.sh
- Add copyright.
- Add libz for unit tests.

* src/sys/dev/random/dummy.c
- Remove; no longer needed. Functionality incorporated into randomdev.*.

* live_entropy_sources.c live_entropy_sources.h
- Remove; content moved.
- move content to randomdev.[ch] and optimise.

* src/sys/dev/random/random_adaptors.c src/sys/dev/random/random_adaptors.h
- Remove; plugability is no longer used. Compile-time algorithm
  selection is the way to go.

* src/sys/dev/random/random_harvestq.c src/sys/dev/random/random_harvestq.h
- Add early (re)boot-time randomness caching.

* src/sys/dev/random/randomdev_soft.c src/sys/dev/random/randomdev_soft.h
- Remove; no longer needed.

* src/sys/dev/random/uint128.h
- Provide a fake uint128_t; if a real one ever arrived, we can use
  that instead. All that is needed here is N=0, N++, N==0, and some
  localised trickery is used to manufacture a 128-bit 0ULLL.

* src/sys/dev/random/unit_test.c src/sys/dev/random/unit_test.h
- Improve unit tests; previously the testing human needed clairvoyance;
  now the test will do a basic check of compressibility. Clairvoyant
  talent is still a good idea.
- This is still a long way off a proper unit test.

* src/sys/dev/random/fortuna.c src/sys/dev/random/fortuna.h
- Improve messy union to just uint128_t.
- Remove unneeded 'static struct fortuna_start_cache'.
- Tighten up up arithmetic.
- Provide a method to allow eternal junk to be introduced; harden
  it against blatant by compress/hashing.
- Assert that locks are held correctly.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Turn into self-sufficient module (no longer requires randomdev_soft.[ch])

* src/sys/dev/random/yarrow.c src/sys/dev/random/yarrow.h
- Improve messy union to just uint128_t.
- Remove unneeded 'staic struct start_cache'.
- Tighten up up arithmetic.
- Provide a method to allow eternal junk to be introduced; harden
  it against blatant by compress/hashing.
- Assert that locks are held correctly.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Turn into self-sufficient module (no longer requires randomdev_soft.[ch])
- Fix some magic numbers elsewhere used as FAST and SLOW.

Differential Revision: https://reviews.freebsd.org/D2025
Reviewed by: vsevolod,delphij,rwatson,trasz,jmg
Approved by: so (delphij)
2015-06-30 17:00:45 +00:00
Neel Natu
1a688aa53e Fix handling of BUS_PROBE_NOWILDCARD in 'device_probe_child()'.
Device probe value of BUS_PROBE_NOWILDCARD should be treated specially only
if the device has a fixed devclass. Otherwise it should be interpreted just
as if the driver doesn't want to claim the device.

Prior to this change a device that was not claimed explicitly by its driver
would remain "attached" to the driver that returned BUS_PROBE_NOWILDCARD.
This would bump up the reference on 'driver->refs' and its 'dev->ops' would
point to the 'driver->ops'. When the driver is subsequently unloaded the
'dev->ops->cls' is left pointing to freed memory.

This fixes an easily reproducible #GP fault caused by loading and unloading
vmm.ko multiple times.

Differential Revision:	https://reviews.freebsd.org/D2294
Reviewed by:	imp, jhb
Discussed with:	rstone
Reported by:	Leon Dang (ldang@nahannisys.com)
MFC after:	2 weeks
2015-04-15 16:22:05 +00:00
Ian Lepore
acfc962f82 Use SYSCTL_OUT_STR() to return strings.
PR:		195668
2015-03-14 21:40:01 +00:00
Ryan Stone
1c229658b9 Fix SR-IOV passthrough devices to allow ppt to attach
A late change to the SR-IOV infrastructure broke passthrough of
VFs.  device_set_devclass() was being used to try to force the
ppt driver to attach to the device, but this didn't work because
the DF_FIXEDCLASS flag wasn't being set on the device, so the
ppt driver probe routine would not match when it returned
BUS_NOWILDCARD.  Fix this by adding a new device function that
both sets the devclass and sets the DF_FIXEDCLASS flag, and use
that to force the ppt driver to attach to VFs.

Differential Revision: https://reviews.freebsd.org/D2041
Reviewed by:	jhb
MFC after:	3 weeks
2015-03-10 23:27:13 +00:00
John Baldwin
64de80195b Add a new device control utility for new-bus devices called devctl. This
allows the user to request administrative changes to individual devices
such as attach or detaching drivers or disabling and re-enabling devices.
- Add a new /dev/devctl2 character device which uses ioctls for device
  requests.  The ioctls use a common 'struct devreq' which is somewhat
  similar to 'struct ifreq'.
- The ioctls identify the device to operate on via a string.  This
  string can either by the device's name, or it can be a bus-specific
  address.  (For unattached devices, a bus address is the only way to
  locate a device.)  Bus drivers register an eventhandler to claim
  unrecognized device names that the driver recognizes as a valid address.
  Two buses currently support addresses: ACPI recognizes any device
  in the ACPI namespace via its full path starting with "\" and
  the PCI bus driver recognizes an address specification of
  'pci[<domain>:]<bus>:<slot>:<func>' (identical to the PCI selector
  strings supported by pciconf).
- To make it easier to cut and paste, change the PnP location string
  in the PCI bus driver to output a full PCI selector string rather
  than 'slot=<slot> function=<func>'.
- Add a devctl(3) interface in libdevctl which provides a wrapper around
  the ioctls and is the preferred interface for other userland code.
- Add a devctl(8) program which is a simple wrapper around the requests
  supported by devctl(3).
- Add a device_is_suspended() function to check DF_SUSPENDED.
- Add a resource_unset_value() function that can be used to remove a
  hint from the kernel environment.  This is used to clear a
  hint.<driver>.<unit>.disabled hint when re-enabling a boot-time
  disabled device.

Reviewed by:	imp (parts)
Requested by:	imp (changing PCI location string)
Relnotes:	yes
2015-02-06 16:09:01 +00:00
John Baldwin
94f0eafcd2 Expose the constants for internal new-bus device flags to userland. The
flag value is already exposed via dv_flags, just not the meaning of the
flags themselves.  Use these constants to annotate devices that are
disabled or suspended in devinfo output.
2015-02-05 22:42:44 +00:00
John Baldwin
a1324315e3 Set and clear the DF_SUSPENDED flag on the child device being manipulated
rather than on the parent.
2015-02-05 22:24:22 +00:00
John Baldwin
531d65e139 Trim trailing whitespace. 2015-01-05 20:50:44 +00:00
John Baldwin
b10c08a52b Revert device_getenv_int() for now as it duplicates resource_int_value().
We should perhaps implement a device_getenv_*() and device_setenv_*() API
as a convenience wrapper on top of resource_*_value() and resource_set_*().
2014-12-03 15:29:53 +00:00
Alfred Perlstein
56c14bca7e Make igb and ixgbe check tunables at probe time.
This allows one to make a kernel module to tune the
number of queues before the driver loads.

This is needed so that a module at SI_SUB_CPU can set
tunables for these drivers to take.  Otherwise getenv
is called too early by the TUNABLE macros.

Reviewed by: smh
Phabric: https://reviews.freebsd.org/D1149
2014-11-26 20:19:36 +00:00
John Baldwin
a2d751936b Add a bus_get_domain() wrapper around BUS_GET_DOMAIN(). Use this to add
a new per-device '%domain' sysctl node that returns the NUMA domain a
device is associated with if it is associated with one.

Note that this API is still a WIP and might change before 11.0 actually
ships.

Differential Revision:	https://reviews.freebsd.org/D930
Reviewed by:	kib, adrian
2014-11-24 19:55:45 +00:00
Mark Murray
10cb24248a This is the much-discussed major upgrade to the random(4) device, known to you all as /dev/random.
This code has had an extensive rewrite and a good series of reviews, both by the author and other parties. This means a lot of code has been simplified. Pluggable structures for high-rate entropy generators are available, and it is most definitely not the case that /dev/random can be driven by only a hardware souce any more. This has been designed out of the device. Hardware sources are stirred into the CSPRNG (Yarrow, Fortuna) like any other entropy source. Pluggable modules may be written by third parties for additional sources.

The harvesting structures and consequently the locking have been simplified. Entropy harvesting is done in a more general way (the documentation for this will follow). There is some GREAT entropy to be had in the UMA allocator, but it is disabled for now as messing with that is likely to annoy many people.

The venerable (but effective) Yarrow algorithm, which is no longer supported by its authors now has an alternative, Fortuna. For now, Yarrow is retained as the default algorithm, but this may be changed using a kernel option. It is intended to make Fortuna the default algorithm for 11.0. Interested parties are encouraged to read ISBN 978-0-470-47424-2 "Cryptography Engineering" By Ferguson, Schneier and Kohno for Fortuna's gory details. Heck, read it anyway.

Many thanks to Arthur Mesh who did early grunt work, and who got caught in the crossfire rather more than he deserved to.

My thanks also to folks who helped me thresh this out on whiteboards and in the odd "Hallway track", or otherwise.

My Nomex pants are on. Let the feedback commence!

Reviewed by:	trasz,des(partial),imp(partial?),rwatson(partial?)
Approved by:	so(des)
2014-10-30 21:21:53 +00:00
Adrian Chadd
ffcf962dab Add a bus method to fetch the VM domain for the given device/bus.
* Add a bus_if.m method - get_domain() - returning the VM domain or
  ENOENT if the device isn't in a VM domain;
* Add bus methods to print out the domain of the device if appropriate;
* Add code in srat.c to save the PXM -> VM domain mapping that's done and
  expose a function to translate VM domain -> PXM;
* Add ACPI and ACPI PCI methods to check if the bus has a _PXM attribute
  and if so map it to the VM domain;
* (.. yes, this works recursively.)
* Have the pci bus glue print out the device VM domain if present.

Note: this is just the plumbing to start enumerating information -
it doesn't at all modify behaviour.

Differential Revision:	D906
Reviewed by:	jhb
Sponsored by:	Norse Corp
2014-10-09 05:33:25 +00:00
John Baldwin
c1d67516d9 Don't panic if a resource is allocated twice. Instead, print a warning and
fail the allocation request.  Allocations of "reserved" resources such as
PCI BARs already fail the request instead of panic'ing in this case.

MFC after:	1 week
2014-09-26 18:37:49 +00:00
Justin Hibbits
a1c1634858 Stage one of multipass suspend/resume
Summary:
Add the beginnings of multipass suspend/resume, by introducing
BUS_SUSPEND_CHILD/BUS_RESUME_CHILD, and move the PCI driver to this.

Reviewers: jhb

Reviewed By: jhb

Differential Revision: https://reviews.freebsd.org/D590
2014-09-23 02:56:40 +00:00
Mateusz Guzik
8bedd5d782 Clear nonblock and async on devctl close instaed of open.
This is a purely cosmetic change.
2014-07-12 15:35:04 +00:00
Hans Petter Selasky
af3b2549c4 Pull in r267961 and r267973 again. Fix for issues reported will follow. 2014-06-28 03:56:17 +00:00
Glen Barber
37a107a407 Revert r267961, r267973:
These changes prevent sysctl(8) from returning proper output,
such as:

 1) no output from sysctl(8)
 2) erroneously returning ENOMEM with tools like truss(1)
    or uname(1)
 truss: can not get etype: Cannot allocate memory
2014-06-27 22:05:21 +00:00
Hans Petter Selasky
3da1cf1e88 Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after:	2 weeks
Sponsored by:	Mellanox Technologies
2014-06-27 16:33:43 +00:00
Brooks Davis
a3fe2bc59e Revert r263754, re-adding support for hw.bus.devctl_disable. Breaking
old devd's and thus hosts that get IP addresses from DHCP was too much
of a POLA violation.

The sysctl may be removed again after r263758 has been merged to at
least stable/9 and stable/10, and releases have been cut from those
branches.

Discussed with:	mjg
Reported by:	theraven, rwatson
2014-04-28 20:38:08 +00:00
David Xu
7d62aec6fe Add kqueue support for devctl.
Reviewed by:	kib,mjg
2014-04-10 02:30:51 +00:00
David Xu
5055c92801 Fix SIGIO delivery. Use fsetown() to handle file descriptor owner
ioctl and use pgsigio() to send SIGIO.

Submitted by:	truckman
Reviewed by:	mjg
2014-04-04 12:31:13 +00:00
Mateusz Guzik
0ab7a1f396 Document a known problem with handling the process intended to receive
SIGIO in /dev/devctl.

Suggested by:	adrian
MFC after:	6 days
2014-03-25 23:30:35 +00:00
Mateusz Guzik
88b7c833d2 Remove long obsolete sysctl hw.bus.devctl_disable.
Suggested by:	imp
Relnotes:	yes
2014-03-25 23:19:45 +00:00
Mateusz Guzik
6abaea7d58 Remove lockless check in devopen, while correct it does not make much sense.
Suggested by:	imp
MFC after:	6 days
2014-03-25 23:13:46 +00:00
Mateusz Guzik
37dbba2a44 Make /dev/devctl mpsafe.
MFC after:	1 week
2014-03-25 03:28:58 +00:00
Dag-Erling Smørgrav
db3fcaf970 Add YARROW_RNG and FORTUNA_RNG to sys/conf/options.
Add a SYSINIT that forces a reseed during proc0 setup, which happens
fairly late in the boot process.

Add a RANDOM_DEBUG option which enables some debugging printf()s.

Add a new RANDOM_ATTACH entropy source which harvests entropy from the
get_cyclecount() delta across each call to a device attach method.
2013-10-08 11:05:26 +00:00
Ryan Stone
08a42caa50 Allow drivers to return BUS_PROBE_NOWILDCARD from their attach routine to
match devices where the driver class was fixed but the unit number was
wildcarded.  This better matches the documented behaviour in
DEVICE_PROBE(9).

Reviewed by:	imp
2013-08-08 19:30:49 +00:00
Craig Rodrigues
719fb72517 PR: 168520 170096
Submitted by: adrian, zec

Fix multiple kernel panics when VIMAGE is enabled in the kernel.
These fixes are based on patches submitted by Adrian Chadd and Marko Zec.

(1)  Set curthread->td_vnet to vnet0 in device_probe_and_attach() just before calling
     device_attach().  This fixes multiple VIMAGE related kernel panics
     when trying to attach Bluetooth or USB Ethernet devices because
     curthread->td_vnet is NULL.

(2)  Set curthread->td_vnet in if_detach().  This fixes kernel panics when detaching networking
     interfaces, especially USB Ethernet devices.

(3)  Use VNET_DOMAIN_SET() in ng_btsocket.c

(4)  In ng_unref_node() set curthread->td_vnet.  This fixes kernel panics
     when detaching Netgraph nodes.
2013-07-15 01:32:55 +00:00
John Baldwin
e35ce1f271 Make detaching drivers from PCI devices more robust. While here, fix a
bug where a PCI device would be powered down if it failed to probe, but
not when its driver was detached (e.g. via kldunload).
- Add a new helper method resource_list_release_active() which forcefully
  releases any active resources of a specified type from a resource list.
- Add a bus_child_detached method for the PCI bus driver which forces any
  active resources to be released (and whines to the console if it finds
  any) and then powers the device down.
- Call pci_child_detached() if we fail to probe a device when a driver
  is kldloaded.  This isn't perfect but can avoid leaking resources
  from a probe() routine in the kldload case.

Reviewed by:	imp, brooks
MFC after:	1 month
2013-06-27 20:21:54 +00:00
John Baldwin
75d774e36a Fix a typo. 2013-01-23 14:37:05 +00:00
Eitan Adler
8dbce2a343 Provide a generic way to disable devices at boot time
PR:		kern/119202
Requested by:	peterj
Reviewed by:	sbruno, jhb
Approved by:	cperciva
MFC after:	1 week
2012-10-02 03:33:41 +00:00
John Baldwin
6f7d0018b0 Add a BUS_CHILD_DELETED() method that a bus can hook to allow it to cleanup
any bus-specific state (such as ivars) when a child device is deleted.

Requested by:	kan
MFC after:	1 month
2012-08-21 18:13:09 +00:00
Hans Petter Selasky
c01fc06ee9 Revert r239178 and implement two new functions, namely
"device_free_softc()" and "device_claim_softc()",
to allow USB serial drivers refcounting the softc.
These functions are used to grab the softc from
auto-free and to free the softc back to the correct
malloc type, respectivly.

Discussed with:	jhb
MFC after:	2 weeks
2012-08-15 15:42:57 +00:00
Hans Petter Selasky
ea1bd564ac Add new device method to free the automatically
allocated softc structure which is returned by
device_get_softc(). This method can be used to
easily implement softc refcounting. This can be
desirable when the softc has memory references
which are controlled by userspace handles for
example.

This solves the problem of blocking the caller
of device_detach() for a non-deterministic time.

Discussed with:	kib, ed
MFC after:	2 weeks
2012-08-10 15:02:49 +00:00
Andriy Gapon
fa44da0995 device_add_child: protect against child device with no driver but fixed unit number
This combination doesn't make sense, unit numbers should be hardwired
only in context of a known driver.  The wildcard devices should have
wildcard unit numbers.

Reviewed by:	jhb
MFC after:	2 weeks
2012-05-25 07:32:26 +00:00
John Baldwin
77b479e644 Allow device_busy() and device_unbusy() to be invoked while a device is
being attached.  This is implemented by adding a new DS_ATTACHING state
while a device's DEVICE_ATTACH() method is being invoked.  A driver is
required to not fail an attach of a busy device.  The device's state will
be promoted to DS_BUSY rather than DS_ACTIVE() if the device was marked
busy during DEVICE_ATTACH().

Reviewed by:	kib
MFC after:	1 week
2012-04-11 20:57:41 +00:00
John Baldwin
0428cbe4df Properly clear a device's devclass if DEVICE_ATTACH() fails if the device
does not have a fixed devclass.

Reviewed by:	imp
MFC after:	2 weeks
2012-02-28 19:16:02 +00:00
John Baldwin
ef7b427562 Clear the a device's description string anytime it's driver changes.
Descriptions  are specific to drivers and we don't change drivers on attached
devices.  This fixes a few places where we were not clearing the description
when detaching a driver (e.g. with device_attach() failed).  While here, fix
a few other nits:
- Remove spurious call to remove a device's driver from
  devclass_driver_deleted().  device_detach() removes it already.
- Fix a typo.
2012-02-27 16:08:18 +00:00
Eitan Adler
886e862866 - Fix undefined behavior when device_get_name is null
- Make error message more informative

PR:		kern/149800
Submitted by:	olgeni
Approved by:	cperciva
MFC after:	1 week
2012-01-15 07:09:18 +00:00
Marius Strobl
002214d6bb It doesn't make much sense to check whether child is NULL after already
having dereferenced it. We either should generally check the device_t's
supplied to bus functions before using them (which we seem to virtually
never do) or just assume that they are not NULL.
While at it make this code fit 78 columns.

Found with:	Coverity Prevent(tm)
CID:		4230
2011-12-02 22:03:27 +00:00
Marius Strobl
f60d6c2bdf - In device_probe_child(9) check the return value of device_set_driver(9)
when actually setting a driver as especially ENOMEM is fatal in these
  cases.
- Annotate other calls to device_set_devclass(9) and device_set_driver(9)
  without the return value being checked and that are okay to fail.

Reviewed by:	yongari (slightly earlier version)
2011-12-02 21:19:14 +00:00
Hans Petter Selasky
3b12bdb58f Rename device_delete_all_children() into device_delete_children().
Suggested by:	jhb @ and marius @
MFC after:	1 week
2011-11-22 21:56:55 +00:00
Hans Petter Selasky
5b288d2abf Style change.
Suggested by:	jhb @ and marius @
MFC after:	1 week
2011-11-22 21:53:19 +00:00
Hans Petter Selasky
11bcf702f4 Move the device_delete_all_children() function from usb_util.c
to kern/subr_bus.c. Simplify this function so that it no longer
depends on malloc() to execute. Identify a few other places where
it makes sense to use device_delete_all_children().

MFC after:	1 week
2011-11-19 10:11:50 +00:00
Marius Strobl
f305d1b0db In device_get_children() avoid malloc(0) in order to increase portability
to other operating systems.

PR:     154287
2011-10-09 21:21:37 +00:00
Kip Macy
8451d0dd78 In order to maximize the re-usability of kernel code in user space this
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.

Reviewed by:	rwatson
Approved by:	re (bz)
2011-09-16 13:58:51 +00:00
John Baldwin
85ee63c923 Add a new bus method, BUS_ADJUST_RESOURCE() that is intended to be a
wrapper around rman_adjust_resource().  Include a generic implementation,
bus_generic_adjust_resource() which passes the request up to the parent
bus.  There is currently no default implementation.  A
bus_adjust_resource() wrapper is provided for use in drivers.
2011-04-29 21:36:45 +00:00
Jeff Roberson
e4cd31dd3c - Merge changes to the base system to support OFED. These include
a wider arg2 for sysctl, updates to vlan code, IFT_INFINIBAND,
   and other miscellaneous small features.
2011-03-21 09:40:01 +00:00
John Baldwin
88690d6a73 Similar to 189574, properly handle subclasses of bus drivers when deleting
a driver during kldunload.  Specifically, recursively walk the tree of
subclasses of a given driver attachment's bus device class detaching all
instances of that driver for each class and its subclasses.

Reported by:	bschmidt
Reviewed by:	imp
MFC after:	1 week
2011-03-01 14:43:37 +00:00