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: Greg 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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg 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: Alan Stern <stern@rowland.harvard.edu>
Acked-by Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus 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: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus 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: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Greg 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: Greg 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: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus 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: Greg 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: Greg 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: Greg 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: Cornelia Huck <cohuck@de.ibm.com>
Signed-off-by: Greg 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: Greg 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: Greg 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: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
- Use it in bus_for_each_drv().
- Use the klist spinlock instead of the bus rwsem.
Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
- Use it for bus_for_each_dev().
- Use the klist spinlock instead of the bus rwsem.
Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg 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: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg 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: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg 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: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg 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: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg 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: Roman Kagan <rkagan@mail.ru>
Signed-off-by: Greg 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!
