PM / freezer: Don't get over-anxious while waiting

Freezing isn't exactly the most latency sensitive operation and
there's no reason to burn cpu cycles and power waiting for it to
complete.  msleep(10) instead of yield().  This should improve
reliability of emergency hibernation.

[rjw: Modified the comment next to the msleep(10).]

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

Conflicts:
	kernel/power/process.c
Freezer: Only show the state of tasks refusing to freeze

show_state will dump all tasks state, so if freezer failed to freeze
any task, kernel will dump all tasks state and flood the dmesg log.
This patch makes freezer only show state of tasks refusing to freeze.

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

Conflicts:
	kernel/power/process.c
Freezer: Fix buggy resume test for tasks frozen with cgroup freezer

When the cgroup freezer is used to freeze tasks we do not want to thaw
those tasks during resume. Currently we test the cgroup freezer
state of the resuming tasks to see if the cgroup is FROZEN.  If so
then we don't thaw the task. However, the FREEZING state also indicates
that the task should remain frozen.

This also avoids a problem pointed out by Oren Ladaan: the freezer state
transition from FREEZING to FROZEN is updated lazily when userspace reads
or writes the freezer.state file in the cgroup filesystem. This means that
resume will thaw tasks in cgroups which should be in the FROZEN state if
there is no read/write of the freezer.state file to trigger this
transition before suspend.

NOTE: Another "simple" solution would be to always update the cgroup
freezer state during resume. However it's a bad choice for several reasons:
Updating the cgroup freezer state is somewhat expensive because it requires
walking all the tasks in the cgroup and checking if they are each frozen.
Worse, this could easily make resume run in N^2 time where N is the number
of tasks in the cgroup. Finally, updating the freezer state from this code
path requires trickier locking because of the way locks must be ordered.

Instead of updating the freezer state we rely on the fact that lazy
updates only manage the transition from FREEZING to FROZEN. We know that
a cgroup with the FREEZING state may actually be FROZEN so test for that
state too. This makes sense in the resume path even for partially-frozen
cgroups -- those that really are FREEZING but not FROZEN.

Reported-by: Oren Ladaan <orenl@cs.columbia.edu>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Cc: stable@kernel.org
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / Hibernate: Snapshot cleanup

Remove support of reads with offset. This means snapshot_read/write_next
now does not accept count parameter. It allows to clean up the functions
and snapshot handle which no longer needs to care about offsets.

/dev/snapshot handler is converted to simple_{read_from,write_to}_buffer
which take care of offsets.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / Hibernate: Separate block_io

Move block I/O operations to a separate file. It is because it will
be used later not only by the swap writer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / Hibernate: Move the first_sector out of swsusp_write

The first sector knowledge is swap-only specific. Move it into the
swap handle. This will be needed for later non-swap specific code
moving into snapshot.c.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl>
PM / Hibernate: Group swap ops

Move all the swap processing into one function. It will make swap
calls from a non-swap code easier.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
PM / Hibernate: Fix block_io.c printk warning

Fix printk format warning in block_io.c:

kernel/power/block_io.c:41: warning: format '%ld' expects type 'long int', but argument 2 has type 'sector_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>