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 <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This adds the infrastructure for drivers to do a threaded probe, and
waits at init time for all currently outstanding probes to complete.
A new kernel thread will be created when the probe() function for the
driver is called, if the multithread_probe bit is set in the driver
saying it can support this kind of operation.
I have tested this with USB and PCI, and it works, and shaves off a lot
of time in the boot process, but there are issues with finding root boot
disks, and some USB drivers assume that this can never happen, so it is
currently not enabled for any bus type. Individual drivers can enable
this right now if they wish, and bus authors can selectivly turn it on
as well, once they determine that their subsystem will work properly
with it.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
We're getting a lot of crashes in the sysfs/kobject/device/bus/class code and
they're very hard to diagnose.
I'm suspecting that in some cases this is because drivers aren't checking
return values and aren't handling errors correctly. So the code blithely
blunders on and crashes later in very obscure ways.
There's just no reason to ignore errors which can and do occur. So the patch
sprinkles __must_check all over these APIs.
Causes 1,513 new warnings. Heh.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Makes it easier for devices to create and remove binary attribute files
so they don't have to call directly into sysfs. This is needed to help
with the conversion from struct class_device to struct device.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
When moving class_device usage over to device, we need to handle
class_interfaces properly with devices. This patch adds that support.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This change creates a devices/virtual/CLASS_NAME tree for struct devices
that belong to a class, yet do not have a "real" struct device for a
parent. It automatically creates the directories on the fly as needed.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This adds two new callbacks to the class structure:
int (*dev_uevent)(struct device *dev, char **envp, int num_envp,
char *buffer, int buffer_size);
void (*dev_release)(struct device *dev);
And one pointer:
struct device_attribute * dev_attrs;
which all corrispond with the same thing as the "normal" class devices
do, yet this is for when a struct device is bound to a class.
Someday soon, struct class_device will go away, and then the other
fields in this structure can be removed too. But this is necessary in
order to get the transition to work properly.
Tested out on a network core patch that converted it to use struct
device instead of struct class_device.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This is needed for the network class devices in order to be able to
convert over to use struct device.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Remove the new suspend_prepare() phase. It doesn't seem very usable,
has never been tested, doesn't address fault cleanup, and would need
a sibling resume_complete(); plus there are no real use cases. It
could be restored later if those issues get resolved.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Allow devices to participate in the suspend process more intimately,
in particular, allow the final phase (with interrupts disabled) to
also be open to normal devices, not just system devices.
Also, allow classes to participate in device suspend.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch (as721) makes dev_info and related macros print the device's
bus name if the device doesn't have a driver, instead of printing just a
blank. If the device isn't on a bus either... well, then it does leave
a blank space. But it will be easier for someone else to change if they
want.
Cc: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This is the first step in moving class_device to being replaced by
struct device. It allows struct device to export a dev_t and makes it
easy to dynamically create and destroy struct device as long as they are
associated with a specific class.
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Extend the support of attribute groups in class_device's to allow
groups to be created as part of the registration process. This allows
network device's to avoid race between registration and creating
groups.
Note that unlike attributes that are a property of the class object,
the groups are a property of the class_device object. This is done
because there are different types of network devices (wireless for
example).
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Both usb.h and device.h have collections of convenience macros for
printk() with the KERN_ERR, KERN_WARNING, and KERN_NOTICE severity
levels. This patch adds macros for the KERN_NOTICE level which was
so far uncatered for.
These macros already exist privately in drivers/isdn/gigaset/gigaset.h
(currently in the process of being submitted for the kernel tree)
but they really belong with their brothers and sisters in
include/linux/{device,usb}.h.
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
