linux.git/drivers/base/bus.c, branch v2.6.20

CONFIG_SYSFS_DEPRECATED - bus symlinks

2006-12-01T22:51:58+00:00

Turn off the bus symlinks if CONFIG_SYSFS_DEPRECATED is enabled

Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

Driver core: add notification of bus events

2006-12-01T22:51:58+00:00

I finally did as you suggested and added the notifier to the struct
bus_type itself. There are still problems to be expected is something
attaches to a bus type where the code can hook in different struct
device sub-classes (which is imho a big bogosity but I won't even try to
argue that case now) but it will solve nicely a number of issues I've
had so far.

That also means that clients interested in registering for such
notifications have to do it before devices are added and after bus types
are registered. Fortunately, most bus types that matter for the various
usage scenarios I have in mind are registerd at postcore_initcall time,
which means I have a really nice spot at arch_initcall time to add my
notifiers.

There are 4 notifications provided. Device being added (before hooked to
the bus) and removed (failure of previous case or after being unhooked
from the bus), along with driver being bound to a device and about to be
unbound.

The usage I have for these are:

 - The 2 first ones are used to maintain a struct device_ext that is
hooked to struct device.firmware_data. This structure contains for now a
pointer to the Open Firmware node related to the device (if any), the
NUMA node ID (for quick access to it) and the DMA operations pointers &
iommu table instance for DMA to/from this device. For bus types I own
(like IBM VIO or EBUS), I just maintain that structure directly from the
bus code when creating the devices. But for bus types managed by generic
code like PCI or platform (actually, of_platform which is a variation of
platform linked to Open Firmware device-tree), I need this notifier.

 - The other two ones have a completely different usage scenario. I have
cases where multiple devices and their drivers depend on each other. For
example, the IBM EMAC network driver needs to attach to a MAL DMA engine
which is a separate device, and a PHY interface which is also a separate
device. They are all of_platform_device's (well, about to be with my
upcoming patches) but there is no say in what precise order the core
will "probe" them and instanciate the various modules. The solution I
found for that is to have the drivers for emac to use multithread_probe,
and wait for a driver to be bound to the target MAL and PHY control
devices (the device-tree contains reference to the MAL and PHY interface
nodes, which I can then match to of_platform_devices). Right now, I've
been polling, but with that notifier, I can more cleanly wait (with a
timeout of course).

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

Driver core: bus: remove indentation level

2006-10-18T19:49:56+00:00

Before potentially fixing up these functions, this cosmetic change
reduces the indentation level to make the code easier to read and
maintain.

No functional changes at all.

Signed-off-by: Jeff Garzik 
Signed-off-by: Greg Kroah-Hartman

Driver core: Don't ignore error returns from probing

2006-10-18T19:49:55+00:00

This patch (as797) fixes device_add() in the driver core.  It needs to
pay attention when the driver for a new device reports an error.

At the same time, since bus_remove_device() undoes the effects of both
bus_add_device() and bus_attach_device(), it needs to check whether
the bus_attach_device step failed.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

driver core fixes: bus_add_device() cleanup on error

2006-10-18T19:49:55+00:00

Correct cleanup in the error path of bus_add_device().

Signed-off-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

driver core fixes: bus_add_attrs() retval check

2006-10-18T19:49:55+00:00

Check return value of bus_add_attrs() in bus_register().

Signed-off-by: Cornelia Huck 
Signed-off-by: Greg Kroah-Hartman

Driver core: Remove unneeded routines from driver core

2006-09-26T04:08:40+00:00

This patch (as783) simplifies the driver core slightly by removing four
unnecessary _get and _put methods.

It is vital that when a driver is removed from its bus's klist of
registered drivers, or when a device is removed from a driver's klist
of bound devices, that the klist updates complete synchronously.
Otherwise the kernel might try binding an unregistered driver to a
newly-registered device, or adding a device to the klist for a new
driver before it has been removed from the old driver's klist.

Since the removals must be synchronous, they don't need to update any
reference counts.  Hence the _get and _put methods can be dispensed
with.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

Driver core: Fix potential deadlock in driver core

2006-09-26T04:08:40+00:00

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: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

drivers/base: check errors

2006-09-26T04:08:39+00:00

Add lots of return-value checking.

: fix bus_rescan_devices()]
Cc: "Randy.Dunlap" 
Signed-off-by: Cornelia Huck 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

Driver core: fixed add_bind_files() definition

2006-09-26T04:08:39+00:00

When CONFIG_HOTPLUG is n, add_bind_files() definition is wrong.
This patch has fixed it.

Signed-off-by: Yoichi Yuasa 
Signed-off-by: Greg Kroah-Hartman