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File: [Development] / linux-2.6-xfs / Documentation / power / notifiers.txt (download)

Revision 1.1, Wed Sep 12 17:09:56 2007 UTC (10 years, 1 month ago) by tes.longdrop.melbourne.sgi.com
Branch: MAIN

Update 2.6.x-xfs to 2.6.23-rc4.

Also update fs/xfs with external mainline changes.
There were 12 such missing commits that I detected:

--------
commit ad690ef9e690f6c31f7d310b09ef1314bcec9033
Author: Al Viro <viro@ftp.linux.org.uk>
    xfs ioctl __user annotations

commit 20c2df83d25c6a95affe6157a4c9cac4cf5ffaac
Author: Paul Mundt <lethal@linux-sh.org>
    mm: Remove slab destructors from kmem_cache_create().

commit d0217ac04ca6591841e5665f518e38064f4e65bd
Author: Nick Piggin <npiggin@suse.de>
    mm: fault feedback #1

commit 54cb8821de07f2ffcd28c380ce9b93d5784b40d7
Author: Nick Piggin <npiggin@suse.de>
    mm: merge populate and nopage into fault (fixes nonlinear)

commit d00806b183152af6d24f46f0c33f14162ca1262a
Author: Nick Piggin <npiggin@suse.de>
    mm: fix fault vs invalidate race for linear mappings

commit a569425512253992cc64ebf8b6d00a62f986db3e
Author: Christoph Hellwig <hch@infradead.org>
    knfsd: exportfs: add exportfs.h header

commit 831441862956fffa17b9801db37e6ea1650b0f69
Author: Rafael J. Wysocki <rjw@sisk.pl>
    Freezer: make kernel threads nonfreezable by default

commit 8e1f936b73150f5095448a0fee6d4f30a1f9001d
Author: Rusty Russell <rusty@rustcorp.com.au>
    mm: clean up and kernelify shrinker registration

commit 5ffc4ef45b3b0a57872f631b4e4ceb8ace0d7496
Author: Jens Axboe <jens.axboe@oracle.com>
    sendfile: remove .sendfile from filesystems that use generic_file_sendfile()

commit 8bb7844286fb8c9fce6f65d8288aeb09d03a5e0d
Author: Rafael J. Wysocki <rjw@sisk.pl>
    Add suspend-related notifications for CPU hotplug

commit 59c51591a0ac7568824f541f57de967e88adaa07
Author: Michael Opdenacker <michael@free-electrons.com>
    Fix occurrences of "the the "

commit 0ceb331433e8aad9c5f441a965d7c681f8b9046f
Author: Dmitriy Monakhov <dmonakhov@openvz.org>
    mm: move common segment checks to separate helper function
--------
Merge of 2.6.x-xfs-melb:linux:29656b by kenmcd.

Suspend notifiers
	(C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL

There are some operations that device drivers may want to carry out in their
.suspend() routines, but shouldn't, because they can cause the hibernation or
suspend to fail. For example, a driver may want to allocate a substantial amount
of memory (like 50 MB) in .suspend(), but that shouldn't be done after the
swsusp's memory shrinker has run.

Also, there may be some operations, that subsystems want to carry out before a
hibernation/suspend or after a restore/resume, requiring the system to be fully
functional, so the drivers' .suspend() and .resume() routines are not suitable
for this purpose.  For example, device drivers may want to upload firmware to
their devices after a restore from a hibernation image, but they cannot do it by
calling request_firmware() from their .resume() routines (user land processes
are frozen at this point).  The solution may be to load the firmware into
memory before processes are frozen and upload it from there in the .resume()
routine.  Of course, a hibernation notifier may be used for this purpose.

The subsystems that have such needs can register suspend notifiers that will be
called upon the following events by the suspend core:

PM_HIBERNATION_PREPARE	The system is going to hibernate or suspend, tasks will
			be frozen immediately.

PM_POST_HIBERNATION	The system memory state has been restored from a
			hibernation image or an error occured during the
			hibernation.  Device drivers' .resume() callbacks have
			been executed and tasks have been thawed.

PM_SUSPEND_PREPARE	The system is preparing for a suspend.

PM_POST_SUSPEND		The system has just resumed or an error occured during
			the suspend.	Device drivers' .resume() callbacks have
			been executed and tasks have been thawed.

It is generally assumed that whatever the notifiers do for
PM_HIBERNATION_PREPARE, should be undone for PM_POST_HIBERNATION.  Analogously,
operations performed for PM_SUSPEND_PREPARE should be reversed for
PM_POST_SUSPEND.  Additionally, all of the notifiers are called for
PM_POST_HIBERNATION if one of them fails for PM_HIBERNATION_PREPARE, and
all of the notifiers are called for PM_POST_SUSPEND if one of them fails for
PM_SUSPEND_PREPARE.

The hibernation and suspend notifiers are called with pm_mutex held.  They are
defined in the usual way, but their last argument is meaningless (it is always
NULL).  To register and/or unregister a suspend notifier use the functions
register_pm_notifier() and unregister_pm_notifier(), respectively, defined in
include/linux/suspend.h .  If you don't need to unregister the notifier, you can
also use the pm_notifier() macro defined in include/linux/suspend.h .