linux-kernel - Re: [PATCH 0/8] Asynchronous device/driver probing support

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Date:	Tue, 3 Feb 2015 15:12:19 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Luis R . Rodriguez" <mcgrof@...e.com>, Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Olof Johansson <olof@...om.net>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Subject: Re: [PATCH 0/8] Asynchronous device/driver probing support

On Fri, Jan 16, 2015 at 03:33:09PM -0800, Dmitry Torokhov wrote:
> 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.
> 
> Thanks,
> Dmitry
> 
> 
> 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(-)
> 
> -- 
> 2.2.0.rc0.207.ga3a616c
> 

*ping*

-- 
Dmitry
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