linux-toradex.git/drivers/base/bus.c, branch v5.14

driver core: Flow the return code from ->probe() through to sysfs bind

2021-06-21T21:29:24+00:00

Currently really_probe() returns 1 on success and 0 if the probe() call
fails. This return code arrangement is designed to be useful for
__device_attach_driver() which is walking the device list and trying every
driver. 0 means to keep trying.

However, it is not useful for the other places that call through to
really_probe() that do actually want to see the probe() return code.

For instance bind_store() would be better to return the actual error code
from the driver's probe method, not discarding it and returning -ENODEV.

Reorganize things so that really_probe() returns the error code from
->probe as a (inverted) positive number, and 0 for successful attach.

With this, __device_attach_driver can ignore the (positive) probe errors,
return 1 to exit the loop for a successful binding and pass on the
other negative errors, while device_driver_attach simplify inverts the
positive errors and returns all errors to the sysfs code.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Cornelia Huck 
Link: https://lore.kernel.org/r/20210617142218.1877096-4-hch@lst.de
Signed-off-by: Alex Williamson

driver core: Pull required checks into driver_probe_device()

2021-06-21T21:29:24+00:00

Checking if the dev is dead or if the dev is already bound is a required
precondition to invoking driver_probe_device(). All the call chains
leading here duplicate these checks.

Add it directly to driver_probe_device() so the precondition is clear and
remove the checks from device_driver_attach() and
__driver_attach_async_helper().

The other call chain going through __device_attach_driver() does have
these same checks but they are inlined into logic higher up the call stack
and can't be removed.

The sysfs uAPI call chain starting at bind_store() is a bit confused
because it reads dev->driver unlocked and returns -ENODEV if it is !NULL,
otherwise it reads it again under lock and returns 0 if it is !NULL. Fix
this to always return -EBUSY and always read dev->driver under its lock.

Done in preparation for the next patches which will add additional
callers to driver_probe_device() and will need these checks as well.

Signed-off-by: Jason Gunthorpe 
[hch: drop the extra checks in device_driver_attach and bind_store]
Signed-off-by: Christoph Hellwig 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Cornelia Huck 
Link: https://lore.kernel.org/r/20210617142218.1877096-2-hch@lst.de
Signed-off-by: Alex Williamson

drivers: base: change 'driver_create_groups' to 'driver_add_groups' in printk

2021-01-27T13:35:09+00:00

driver_create_groups doesn't seem to have ever existed. Change its
mention in a printk to 'driver_add_groups'.

Signed-off-by: Joe Pater <02joepater06@gmail.com>
Link: https://lore.kernel.org/r/20210110145442.15301-1-02joepater06@gmail.com
Signed-off-by: Greg Kroah-Hartman

drivers: base: remove unused function find_bus()

2021-01-07T19:33:03+00:00

find_bus() isn't doing anyone any good sitting in a '#if 0' (as it's
been doing since 2006!).

Signed-off-by: Joe Pater <02joepater06@gmail.com>
Link: https://lore.kernel.org/r/20210103203238.111565-1-02joepater06@gmail.com
Signed-off-by: Greg Kroah-Hartman

drivers core: Miscellaneous changes for sysfs_emit

2020-10-02T11:12:07+00:00

Change additional instances that could use sysfs_emit and sysfs_emit_at
that the coccinelle script could not convert.

o macros creating show functions with ## concatenation
o unbound sprintf uses with buf+len for start of output to sysfs_emit_at
o returns with ?: tests and sprintf to sysfs_emit
o sysfs output with struct class * not struct device * arguments

Miscellanea:

o remove unnecessary initializations around these changes
o consistently use int len for return length of show functions
o use octal permissions and not S_
o rename a few show function names so DEVICE_ATTR_ can be used
o use DEVICE_ATTR_ADMIN_RO where appropriate
o consistently use const char *output for strings
o checkpatch/style neatening

Signed-off-by: Joe Perches 
Link: https://lore.kernel.org/r/8bc24444fe2049a9b2de6127389b57edfdfe324d.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman

device.h: move 'struct bus' stuff out to device/bus.h

2019-12-16T09:11:12+00:00

device.h has everything and the kitchen sink when it comes to struct
device things, so split out the struct bus things things to a separate
.h file to make things easier to maintain and manage over time.

Cc: "Rafael J. Wysocki" 
Cc: Suzuki K Poulose 
Cc: Saravana Kannan 
Cc: Heikki Krogerus 
Link: https://lore.kernel.org/r/20191209193303.1694546-5-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman

drivers: Introduce device lookup variants by name

2019-07-30T11:07:41+00:00

Add a helper to match the device name for device lookup. Also
reuse this generic exported helper for the existing bus_find_device_by_name().
and add similar variants for driver/class.

Cc: Alessandro Zummo 
Cc: Alexander Aring 
Cc: Alexander Shishkin 
Cc: Arnd Bergmann 
Cc: Dan Murphy 
Cc: Harald Freudenberger 
Cc: Heiko Carstens 
Cc: Jacek Anaszewski 
Cc: Lee Jones 
Cc: linux-leds@vger.kernel.org
Cc: linux-rtc@vger.kernel.org
Cc: linux-usb@vger.kernel.org
Cc: linux-wpan@vger.kernel.org
Cc: Maxime Coquelin 
Cc: Pavel Machek 
Cc: Peter Oberparleiter 
Cc: "Rafael J. Wysocki" 
Cc: Stefan Schmidt 
Cc: Greg Kroah-Hartman 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Suzuki K Poulose 
Reviewed-by: Heikki Krogerus 
Acked-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20190723221838.12024-2-suzuki.poulose@arm.com
Signed-off-by: Greg Kroah-Hartman

bus_find_device: Unify the match callback with class_find_device

2019-06-24T03:22:31+00:00

There is an arbitrary difference between the prototypes of
bus_find_device() and class_find_device() preventing their callers
from passing the same pair of data and match() arguments to both of
them, which is the const qualifier used in the prototype of
class_find_device().  If that qualifier is also used in the
bus_find_device() prototype, it will be possible to pass the same
match() callback function to both bus_find_device() and
class_find_device(), which will allow some optimizations to be made in
order to avoid code duplication going forward.  Also with that, constify
the "data" parameter as it is passed as a const to the match function.

For this reason, change the prototype of bus_find_device() to match
the prototype of class_find_device() and adjust its callers to use the
const qualifier in accordance with the new prototype of it.

Cc: Alexander Shishkin 
Cc: Andrew Lunn 
Cc: Andreas Noever 
Cc: Arnd Bergmann 
Cc: Bjorn Helgaas 
Cc: Corey Minyard 
Cc: Christian Borntraeger 
Cc: David Kershner 
Cc: "David S. Miller" 
Cc: David Airlie 
Cc: Felipe Balbi 
Cc: Frank Rowand 
Cc: Grygorii Strashko 
Cc: Harald Freudenberger 
Cc: Hartmut Knaack 
Cc: Heiko Stuebner 
Cc: Jason Gunthorpe 
Cc: Jonathan Cameron 
Cc: "James E.J. Bottomley" 
Cc: Len Brown 
Cc: Mark Brown 
Cc: Michael Ellerman 
Cc: Michael Jamet 
Cc: "Martin K. Petersen" 
Cc: Peter Oberparleiter 
Cc: Sebastian Ott 
Cc: Srinivas Kandagatla 
Cc: Yehezkel Bernat 
Cc: rafael@kernel.org
Acked-by: Corey Minyard 
Acked-by: David Kershner 
Acked-by: Mark Brown 
Acked-by: Rafael J. Wysocki 
Acked-by: Srinivas Kandagatla 
Acked-by: Wolfram Sang  # for the I2C parts
Acked-by: Rob Herring 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Greg Kroah-Hartman

driver core: Probe devices asynchronously instead of the driver

2019-01-31T13:20:53+00:00

Probe devices asynchronously instead of the driver. This results in us
seeing the same behavior if the device is registered before the driver or
after. This way we can avoid serializing the initialization should the
driver not be loaded until after the devices have already been added.

The motivation behind this is that if we have a set of devices that
take a significant amount of time to load we can greatly reduce the time to
load by processing them in parallel instead of one at a time. In addition,
each device can exist on a different node so placing a single thread on one
CPU to initialize all of the devices for a given driver can result in poor
performance on a system with multiple nodes.

This approach can reduce the time needed to scan SCSI LUNs significantly.
The only way to realize that speedup is by enabling more concurrency which
is what is achieved with this patch.

To achieve this it was necessary to add a new member "async_driver" to the
device_private structure to store the driver pointer while we wait on the
deferred probe call.

Reviewed-by: Bart Van Assche 
Reviewed-by: Dan Williams 
Signed-off-by: Alexander Duyck 
Reviewed-by: Rafael J. Wysocki 
Signed-off-by: Greg Kroah-Hartman

device core: Consolidate locking and unlocking of parent and device

2019-01-31T13:20:53+00:00

Try to consolidate all of the locking and unlocking of both the parent and
device when attaching or removing a driver from a given device.

To do that I first consolidated the lock pattern into two functions
__device_driver_lock and __device_driver_unlock. After doing that I then
created functions specific to attaching and detaching the driver while
acquiring these locks. By doing this I was able to reduce the number of
spots where we touch need_parent_lock from 12 down to 4.

This patch should produce no functional changes, it is meant to be a code
clean-up/consolidation only.

Reviewed-by: Luis Chamberlain 
Reviewed-by: Bart Van Assche 
Reviewed-by: Dan Williams 
Reviewed-by: Rafael J. Wysocki 
Signed-off-by: Alexander Duyck 
Signed-off-by: Greg Kroah-Hartman