There is a potential deadlock in the driver core.  It boils down to
the fact that bus_remove_device() calls klist_remove() instead of
klist_del(), thereby waiting until the reference count of the
klist_node in the bus's klist of devices drops to 0.  The refcount
can't reach 0 so long as a modprobe process is trying to bind a new
driver to the device being removed, by calling __driver_attach().  The
problem is that __driver_attach() tries to acquire the device's
parent's semaphore, but the caller of bus_remove_device() is quite
likely to own that semaphore already.

It isn't sufficient just to replace klist_remove() with klist_del().
Doing so runs the risk that the device would remain on the bus's klist
of devices for some time, and so could be bound to another driver even
after it was unregistered.  What's needed is a new way to distinguish
whether or not a device is registered, based on a criterion other than
whether its klist_node is linked into the bus's klist of devices.  That
way driver binding can fail when the device is unregistered, even if
it is still linked into the klist.

This patch (as782) implements the solution, by adding a new bitflag to
indiate when a struct device is registered, by testing the flag before
allowing a driver to bind a device, and by changing the definition of
the device_is_registered() inline.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add lots of return-value checking.

<pcornelia.huck@de.ibm.com>: fix bus_rescan_devices()]
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

When CONFIG_HOTPLUG is n, add_bind_files() definition is wrong.
This patch has fixed it.
Signed-off-by: NYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch contains the following cleanups:
- make the needlessly global bus_subsys static
- #if 0 the unused find_bus()
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Like the SUBSYTEM= key we find in the environment of the uevent, this
creates a generic "subsystem" link in sysfs for every device. Userspace
usually doesn't care at all if its a "class" or a "bus" device. This
provides an unified way to determine the subsytem of a device, regardless
of the way the driver core has created it.
Signed-off-by: NKay Sievers <kay.sievers@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

split bus_add_device() and send device uevents after sysfs population
Signed-off-by: NKay Sievers <kay.sievers@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The manual driver <-> device binding attribute in sysfs doesn't return
the correct value on failure or success of driver_probe_device.
driver_probe_device returns 1 on success (the driver accepted the
device) or 0 on probe failure (when the driver didn't accept the
device but no real error occured). However, the attribute can't just
return 0 or 1, it must return the number of bytes consumed from buf
or an error value. Returning 0 indicates to userspace that nothing
was written (even though the kernel has tried to do the bind/probe and
failed). Returning 1 indicates that only one character was accepted in
which case userspace will re-try the write with a partial string.

A more correct version of driver_bind would return count (to indicate
the entire string was consumed) when driver_probe_device returns 1
and -ENODEV when driver_probe_device returns 0. This patch makes that
change.
Signed-off-by: NRyan Wilson <hap9@epoch.ncsc.mil>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Adding support for exposing hidden raid components for sg
interface. The sdev->no_uld_attach flag will set set accordingly.

The sas module supports adding/removing raid volumes using online
storage management application interface.

This patch was provided to me by Christoph Hellwig.
Signed-off-by: NEric Moore <Eric.Moore@lsil.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

drivers/base/bus.c:166: warning: `driver_attr_unbind' defined but not used
drivers/base/bus.c:194: warning: `driver_attr_bind' defined but not used

Looks like these two attributes and supporting functions want to be
#ifdef HOTPLUG'd
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

FYI, while running a build test, I found:

drivers/base/bus.c:166: warning: `driver_attr_unbind' defined but not used
drivers/base/bus.c:194: warning: `driver_attr_bind' defined but not used

Looks like these two attributes and supporting functions want to be
#ifdef HOTPLUG'd
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Thanks to drivers making their id tables __devinit, we can't allow
userspace to bind or unbind drivers from devices manually through sysfs.
So we only allow this if CONFIG_HOTPLUG is enabled.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch (as604) makes the driver core hold a device's parent's lock
as well as the device's lock during calls to the probe and remove
methods in a driver.  This facility is needed by USB device drivers,
owing to the peculiar way USB devices work:

	A device provides multiple interfaces, and drivers are bound
	to interfaces rather than to devices;

	Nevertheless a reset, reset-configuration, suspend, or resume
	affects the entire device and requires the caller to hold the
	lock for the device, not just a lock for one of the interfaces.

Since a USB driver's probe method is always called with the interface
lock held, the locking order rules (always lock parent before child)
prevent these methods from acquiring the device lock.  The solution
provided here is to call all probe and remove methods, for all devices
(not just USB), with the parent lock already acquired.

Although currently only the USB subsystem requires these changes, people
have mentioned in prior discussion that the overhead of acquiring an
extra semaphore in all the prove/remove sequences is not overly large.

Up to now, the USB core has been using its own set of private
semaphores.  A followup patch will remove them, relying entirely on the
device semaphores provided by the driver core.

The code paths affected by this patch are:

	device_add and device_del: The USB core already holds the parent
	lock, so no actual change is needed.

	driver_register and driver_unregister: The driver core will now
	lock both the parent and the device before probing or removing.

	driver_bind and driver_unbind (in sysfs): These routines will
	now lock both the parent and the device before binding or
	unbinding.

	bus_rescan_devices: The helper routine will lock the parent
	before probing a device.

I have not tested this patch for conflicts with other subsystems.  As
far as I can see, the only possibility of conflict would lie in the
bus_rescan_devices pathway, and it seems pretty remote.  Nevertheless,
it would be good for this to get a lot of testing in -mm.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch (as603) makes a few small fixes to the driver core:

Change spin_lock_irq for a klist lock to spin_lock;

Fix reference count leaks;

Minor spelling and formatting changes.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Acked-by Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The problem is that klists claim to provide semantics for safe traversal of
lists which are being modified.  The failure case is when traversal of a
list causes element removal (a fairly common case).  The issue is that
although the list node is refcounted, if it is embedded in an object (which
is universally the case), then the object will be freed regardless of the
klist refcount leading to slab corruption because the klist iterator refers
to the prior element to get the next.

The solution is to make the klist take and release references to the
embedding object meaning that the embedding object won't be released until
the list relinquishes the reference to it.

(akpm: fast-track this because it's needed for the 2.6.13 scsi merge)
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

at the moment, the list_head semantics are

list_add(node, head)

whereas current klist semantics are

klist_add(head, node)

This is bound to cause confusion, and since klist is the newcomer, it
should follow the list_head semantics.

I also added missing include guards to klist.h
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Fix for manual binding of drivers to devices.  Problem is if you pass in
a valid device id, but the driver refuses to bind.  Infinite loop as
write() tries to resubmit the data it just sent.

Thanks to Michal Ostrowski <mostrows@watson.ibm.com> for pointing the
problem out.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Fix for manual binding of drivers to devices.  Problem is if you pass in
a valid device id, but the driver refuses to bind.  Infinite loop as
write() tries to resubmit the data it just sent.

Thanks to Michal Ostrowski <mostrows@watson.ibm.com> for pointing the
problem out.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

No one was looking at the return value of bus_rescan_devices, and it
really wasn't anything that anyone in the kernel would ever care about.
So change it which enabled some counting code to be removed also.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This adds a single file, "bind", to the sysfs directory of every driver
registered with the driver core.  To bind a device to a driver, write
the bus id of the device you wish to bind to that specific driver to the
"bind" file (remember to not add a trailing \n).  If that bus id matches
a device on that bus, and it does not currently have a driver bound to
it, the probe sequence will be initiated with that driver and device.

Note, this requires that the driver itself be willing and able to accept
that device (usually through a device id type table).  This patch does
not make it possible to override the driver's id table.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This adds a single file, "unbind", to the sysfs directory of every
device that is currently bound to a driver.  To unbind the driver from
the device, write anything to this file and they will be disconnected
from each other.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add bus_find_device() and driver_find_device() which allow searching for a
device in the bus's resp. the driver's klist and obtain a reference on it.
Signed-off-by: NCornelia Huck <cohuck@de.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Don't error out if something "bad" happens when trying to bind a driver to a
device.  We want the sysfs attributes to be present for later when we try to
tear down the device.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The error handling in bus_add_device() and device_attach() is simply
non-existing. This patch propagates any error from device_attach to
the upper layers to allow for a proper recovery.

From: Hannes Reinecke <hare@suse.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

- Don't add devices to bus's embedded kset, since it's not used by anyone anymore.
- Don't need to take the bus rwsem when calling {device,driver}_attach(), since
  those functions use the klists and the klists' spinlocks.
Signed-off-by: NPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

- Use it in bus_for_each_drv().
- Use the klist spinlock instead of the bus rwsem.
Signed-off-by: NPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

- Use it for bus_for_each_dev().
- Use the klist spinlock instead of the bus rwsem.
Signed-off-by: NPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This relocates the driver binding/unbinding code to drivers/base/dd.c. This is done
for two reasons: One, it's not code related to the bus_type itself; it uses some from
that, some from devices, and some from drivers. And Two, it will make it easier to do
some of the upcoming lock removal on that code..
Signed-off-by: NPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This adds a per-device semaphore that is taken before every call from the core to a
driver method. This prevents e.g. simultaneous calls to the ->suspend() or ->resume()
and ->probe() or ->release(), potentially saving a whole lot of headaches.

It also moves us a step closer to removing the bus rwsem, since it protects the fields
in struct device that are modified by the core.
Signed-off-by: NPatrick Mochel <mochel@digitalimplant.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

sysfs: fix drivers/base so if an attribute doesn't implement
       show or store method read/write will return -EIO
       instead of 0.
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The driver model has a "detach_state" mechanism that:

 - Has never been used by any in-kernel drive;
 - Is superfluous, since driver remove() methods can do the same thing;
 - Became buggy when the suspend() parameter changed semantics and type;
 - Could self-deadlock when called from certain suspend contexts;
 - Is effectively wasted documentation, object code, and headspace.

This removes that "detach_state" mechanism; net code shrink, as well
as a per-device saving in the driver model and sysfs.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

With 2.6.11 and 2.6.12-rc2 (and perhaps a few versions before) usb
drivers for multi-interface devices, which do
usb_driver_release_interface() in their disconnect(), make rmmod hang.

It turns out to be due to a bug in drivers/base/bus.c:driver_detach(),
that iterates over the list of attached devices with
list_for_each_safe() under an assumption that device_release_driver()
only releases the current device, while it may also call
device_release_driver() for other devices on the same list.

The following patch fixes it.  Please consider applying.
Signed-off-by: NRoman Kagan <rkagan@mail.ru>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!