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

From: Dmitry Torokhov
Date: Tue Mar 03 2015 - 16:19:01 EST


On Sat, Feb 07, 2015 at 06:06:15PM +0800, Greg Kroah-Hartman wrote:
> On Tue, Feb 03, 2015 at 03:12:19PM -0800, Dmitry Torokhov wrote:
> > 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*
>
> Sorry, I was waiting for someone else here to speak up.
>
> It's too late for 3.20, I'll look at this when 3.20-rc1 is out, thanks,

Greg, please take another look.

Thanks!

--
Dmitry
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