[lkml]   [2011]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Subject[PATCH 9-10/10] Allow subsystems to avoid using sysdevs for defining "core" PM callbacks
On Saturday, March 12, 2011, Rafael J. Wysocki wrote:
> Hi,
> On Thursday, March 10, 2011, Rafael J. Wysocki wrote:
> > There are multiple problems with sysdevs, or struct sys_device objects to
> > be precise, that are so annoying that some people have started to think
> > of removind them entirely from the kernel. To me, personally, the most
> > obvious issue is the way sysdevs are used for defining suspend/resume
> > callbacks to be executed with one CPU on-line and interrupts disabled.
> > Greg and Kay may tell you more about the other problems with sysdevs. :-)
> >
> > Some subsystems need to carry out certain operations during suspend after
> > we've disabled non-boot CPUs and interrupts have been switched off on the
> > only on-line one. Currently, the only way to achieve that is to define
> > sysdev suspend/resume callbacks, but this is cumbersome and inefficient.
> > Namely, to do that, one has to define a sysdev class providing the callbacks
> > and a sysdev actually using them, which is excessively complicated. Moreover,
> > the sysdev suspend/resume callbacks take arguments that are not really used
> > by the majority of subsystems defining sysdev suspend/resume callbacks
> > (or even if they are used, they don't really _need_ to be used, so they
> > are simply unnecessary). Of course, if a sysdev is only defined to provide
> > suspend/resume (and maybe shutdown) callbacks, there's no real reason why
> > it should show up in sysfs.
> >
> > For this reason, I thought it would be a good idea to provide a simpler
> > interface for subsystems to define "very late" suspend callbacks and
> > "very early" resume callbacks (and "very late" shutdown callbacks as well)
> > without the entire bloat related to sysdevs. The interface is introduced
> > by the first of the following patches, while the second patch converts some
> > sysdev users related to the x86 architecture to using the new interface.
> >
> > I believe that call sysdev users who need to define suspend/resume/shutdown
> > callbacks may be converted to using the interface provided by the first patch,
> > which in turn should allow us to convert the remaining sysdev functionality
> > into "normal" struct device interfaces. Still, even if that turns out to be
> > too complicated, the bloat reduction resulting from the second patch kind of
> > shows that moving at least some sysdev users to a simpler interface (like in
> > the first patch) is a good idea anyway.
> >
> > This is a proof of concept, so the patches have not been tested. Please be
> > extrememly careful, because they touch sensitive code, so to speak. In the
> > majority of cases the changes are rather straightforward, but there are some
> > more interesting cases as well (io_apic.c most importantly).
> Since Greg likes the idea and there haven't been any objections so far, here's
> the official submission. The patches have been tested on HP nx6325 and
> Toshiba Portege R500.
> Patch [1/8] is regareded as 2.6.38 material, following Greg's advice. The
> other patches in the set are regarded as 2.6.39 material. The last one
> obviously depends on all of the previous ones.
> [1/8] - Introduce struct syscore_ops for registering operations to be run on
> one CPU during suspend/resume/shutdown.
> [2/8] - Convert sysdev users in arch/x86 to using struct syscore_ops.
> [3/8] - Make ACPI use struct syscore_ops for irqrouter_resume().
> [4/8] - Make timekeeping use struct syscore_ops for suspend/resume.
> [5/8] - Make Intel IOMMU use struct syscore_ops for suspend/resume.
> [6/8] - Make KVM use struct syscore_ops for suspend/resume.
> [7/8] - Make cpufreq use struct syscore_ops for boot CPU suspend/resume.
> [8/8] - Introduce config switch allowing architectures to skip sysdev
> suspend/resume/shutdown code.
> If there are no objectsions, I'd like to push these patches through the suspend
> tree.

A little followup with two ARM-related patches.

[9/10] - Make sh drivers use struct syscore_ops for suspend/resume (instead of
[10/10] - Use struct syscore_ops for suspend/resume (instead of sysdevs) in
core ARM code.


 \ /
  Last update: 2011-03-13 14:07    [W:0.279 / U:5.104 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site