[PATCH 0/8] Asynchronous device/driver probing support

From: Dmitry Torokhov
Date: Fri Jan 16 2015 - 18:33:35 EST

This series is a combination of changes proposed by Luis a couple months
ago and implementation used by Chrome OS. The issue we are trying to solve
here is "slow" devices and drivers spending "too much time" in their probe()
methods and it affects:

- overall kernel boot process when drivers are compiled into the kernel
and slow devices stall entire boot progress;
- systemd desire to time out module loading process.

Unlike Luis' proposal we do make use of asycn_schedule() infrastructure
instead of using a dedicated workqueue, so all existing synchronization
points in kernel that wait for device registration still work the same.
Also, the asynchronous probing is done not only during driver registration
(i.e. when devices are probed asynchronously only if they are registered
before the driver), but also during device registration and deferred probe
handling. This way slow devices do not stall kernel boot even when drivers
are compiled into the kernel.

The last patch is for adventurous people to try and force
fully-asynchronous boot. It works for me with limited success - I can boot
Rockhip-based box to userspace as long as I force serial to be sychronously
probed and ignore the fact that most devices are using "dummy" regulators
as regulator subsystem really expects regulators to be registered in
orderly fashion on OF-based systems.


Dmitry Torokhov (3):
driver-core: add asynchronous probing support for drivers
driver-core: platform_driver_probe() must probe synchronously
module: add core_param_unsafe

Luis R. Rodriguez (5):
module: add extra argument for parse_params() callback
driver-core: add driver module asynchronous probe support
driver-core: enable drivers to opt-out of async probe
amd64_edac: enforce synchronous probe
driver-core: allow forcing async probing for modules and builtins

Documentation/kernel-parameters.txt | 13 +++
arch/powerpc/mm/hugetlbpage.c | 4 +-
drivers/base/base.h | 1 +
drivers/base/bus.c | 31 +++++--
drivers/base/dd.c | 166 +++++++++++++++++++++++++++++++-----
drivers/base/platform.c | 13 +++
drivers/edac/amd64_edac.c | 1 +
include/linux/device.h | 26 ++++++
include/linux/module.h | 2 +
include/linux/moduleparam.h | 12 ++-
init/main.c | 25 +++---
kernel/module.c | 25 +++++-
kernel/params.c | 11 ++-
lib/dynamic_debug.c | 4 +-
14 files changed, 284 insertions(+), 50 deletions(-)


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