Commit Graph

60 Commits

Author SHA1 Message Date
Rafael J. Wysocki 05d658b5b5 Merge branch 'pm-sleep'
* pm-sleep:
  freezer: Fix typo in freezable_schedule_timeout() comment
  PM / s2idle: Clear the events_check_enabled flag
  PM / sleep: Remove pm_complete_with_resume_check()
  PM: ARM: locomo: Drop suspend and resume bus type callbacks
  PM: Use a more common logging style
  PM: Document rules on using pm_runtime_resume() in system suspend callbacks
2017-11-13 01:41:20 +01:00
Himanshu Jha 2dd9789c76 freezer: Fix typo in freezable_schedule_timeout() comment
Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-11-08 23:54:27 +01:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
John Stultz da8b44d5a9 timer: convert timer_slack_ns from unsigned long to u64
This patchset introduces a /proc/<pid>/timerslack_ns interface which
would allow controlling processes to be able to set the timerslack value
on other processes in order to save power by avoiding wakeups (Something
Android currently does via out-of-tree patches).

The first patch tries to fix the internal timer_slack_ns usage which was
defined as a long, which limits the slack range to ~4 seconds on 32bit
systems.  It converts it to a u64, which provides the same basically
unlimited slack (500 years) on both 32bit and 64bit machines.

The second patch introduces the /proc/<pid>/timerslack_ns interface
which allows the full 64bit slack range for a task to be read or set on
both 32bit and 64bit machines.

With these two patches, on a 32bit machine, after setting the slack on
bash to 10 seconds:

$ time sleep 1

real    0m10.747s
user    0m0.001s
sys     0m0.005s

The first patch is a little ugly, since I had to chase the slack delta
arguments through a number of functions converting them to u64s.  Let me
know if it makes sense to break that up more or not.

Other than that things are fairly straightforward.

This patch (of 2):

The timer_slack_ns value in the task struct is currently a unsigned
long.  This means that on 32bit applications, the maximum slack is just
over 4 seconds.  However, on 64bit machines, its much much larger (~500
years).

This disparity could make application development a little (as well as
the default_slack) to a u64.  This means both 32bit and 64bit systems
have the same effective internal slack range.

Now the existing ABI via PR_GET_TIMERSLACK and PR_SET_TIMERSLACK specify
the interface as a unsigned long, so we preserve that limitation on
32bit systems, where SET_TIMERSLACK can only set the slack to a unsigned
long value, and GET_TIMERSLACK will return ULONG_MAX if the slack is
actually larger then what can be stored by an unsigned long.

This patch also modifies hrtimer functions which specified the slack
delta as a unsigned long.

Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17 15:09:34 -07:00
Peter Zijlstra (Intel) 5d4d565824 sched/wait: Remove wait_event_freezekillable()
There is no user.. make it go away.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:46 +01:00
Peter Zijlstra 36df04bc52 sched/wait: Reimplement wait_event_freezable()
Provide better implementations of wait_event_freezable() APIs.

The problem is with freezer_do_not_count(), it hides the thread from
the freezer, even though this thread might not actually freeze/sleep
at all.

Cc: oleg@redhat.com
Cc: Rafael Wysocki <rjw@rjwysocki.net>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-d86fz1jmso9wjxa8jfpinp8o@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-11-04 07:17:45 +01:00
Colin Cross dd5ec0f4e7 freezer: add new freezable helpers using freezer_do_not_count()
Freezing tasks will wake up almost every userspace task from
where it is blocking and force it to run until it hits a
call to try_to_sleep(), generally on the exit path from the syscall
it is blocking in.  On resume each task will run again, usually
restarting the syscall and running until it hits the same
blocking call as it was originally blocked in.

To allow tasks to avoid running on every suspend/resume cycle,
this patch adds additional freezable wrappers around blocking calls
that call freezer_do_not_count().  Combined with the previous patch,
these tasks will not run during suspend or resume unless they wake
up for another reason, in which case they will run until they hit
the try_to_freeze() in freezer_count(), and then continue processing
the wakeup after tasks are thawed.

Additional patches will convert the most common locations that
userspace blocks in to use freezable helpers.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:22 +02:00
Colin Cross 8ee492d659 freezer: convert freezable helpers to static inline where possible
Some of the freezable helpers have to be macros because their
condition argument needs to get evaluated every time through
the wait loop.  Convert the others to static inline to make
future changes easier.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:22 +02:00
Colin Cross b01235861b freezer: convert freezable helpers to freezer_do_not_count()
Freezing tasks will wake up almost every userspace task from
where it is blocking and force it to run until it hits a
call to try_to_sleep(), generally on the exit path from the syscall
it is blocking in.  On resume each task will run again, usually
restarting the syscall and running until it hits the same
blocking call as it was originally blocked in.

Convert the existing wait_event_freezable* wrappers to use
freezer_do_not_count().  Combined with a previous patch,
these tasks will not run during suspend or resume unless they wake
up for another reason, in which case they will run until they hit
the try_to_freeze() in freezer_count(), and then continue processing
the wakeup after tasks are thawed.

This results in a small change in behavior, previously a race
between freezing and a normal wakeup would be won by the wakeup,
now the task will freeze and then handle the wakeup after thawing.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:22 +02:00
Mandeep Singh Baines 0f9548ca10 lockdep: check that no locks held at freeze time
We shouldn't try_to_freeze if locks are held.  Holding a lock can cause a
deadlock if the lock is later acquired in the suspend or hibernate path
(e.g.  by dpm).  Holding a lock can also cause a deadlock in the case of
cgroup_freezer if a lock is held inside a frozen cgroup that is later
acquired by a process outside that group.

History:
This patch was originally applied as 6aa9707099 and reverted in
dbf520a9d7 because NFS was freezing with locks held.  It was
deemed better to keep the bad freeze point in NFS to allow laptops
to suspend consistently.  The previous patch in this series converts
NFS to call _unsafe versions of the freezable helpers so that
lockdep doesn't complain about them until a more correct fix
can be applied.

[akpm@linux-foundation.org: export debug_check_no_locks_held]
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:22 +02:00
Colin Cross 5853cc2a89 freezer: add unsafe versions of freezable helpers for CIFS
CIFS calls wait_event_freezekillable_unsafe with a VFS lock held,
which is unsafe and will cause lockdep warnings when 6aa9707
"lockdep: check that no locks held at freeze time" is reapplied
(it was reverted in dbf520a).  CIFS shouldn't be doing this, but
it has long-running syscalls that must hold a lock but also
shouldn't block suspend.  Until CIFS freeze handling is rewritten
to use a signal to exit out of the critical section, add a new
wait_event_freezekillable_unsafe helper that will not run the
lockdep test when 6aa9707 is reapplied, and call it from CIFS.

In practice the likley result of holding the lock while freezing
is that a second task blocked on the lock will never freeze,
aborting suspend, but it is possible to manufacture a case using
the cgroup freezer, the lock, and the suspend freezer to create
a deadlock.  Silencing the lockdep warning here will allow
problems to be found in other drivers that may have a more
serious deadlock risk, and prevent new problems from being added.

Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:21 +02:00
Colin Cross 416ad3c9c0 freezer: add unsafe versions of freezable helpers for NFS
NFS calls the freezable helpers with locks held, which is unsafe
and will cause lockdep warnings when 6aa9707 "lockdep: check
that no locks held at freeze time" is reapplied (it was reverted
in dbf520a).  NFS shouldn't be doing this, but it has
long-running syscalls that must hold a lock but also shouldn't
block suspend.  Until NFS freeze handling is rewritten to use a
signal to exit out of the critical section, add new *_unsafe
versions of the helpers that will not run the lockdep test when
6aa9707 is reapplied, and call them from NFS.

In practice the likley result of holding the lock while freezing
is that a second task blocked on the lock will never freeze,
aborting suspend, but it is possible to manufacture a case using
the cgroup freezer, the lock, and the suspend freezer to create
a deadlock.  Silencing the lockdep warning here will allow
problems to be found in other drivers that may have a more
serious deadlock risk, and prevent new problems from being added.

Signed-off-by: Colin Cross <ccross@android.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:16:21 +02:00
Paul Walmsley dbf520a9d7 Revert "lockdep: check that no locks held at freeze time"
This reverts commit 6aa9707099.

Commit 6aa9707099 ("lockdep: check that no locks held at freeze time")
causes problems with NFS root filesystems.  The failures were noticed on
OMAP2 and 3 boards during kernel init:

  [ BUG: swapper/0/1 still has locks held! ]
  3.9.0-rc3-00344-ga937536 #1 Not tainted
  -------------------------------------
  1 lock held by swapper/0/1:
   #0:  (&type->s_umount_key#13/1){+.+.+.}, at: [<c011e84c>] sget+0x248/0x574

  stack backtrace:
    rpc_wait_bit_killable
    __wait_on_bit
    out_of_line_wait_on_bit
    __rpc_execute
    rpc_run_task
    rpc_call_sync
    nfs_proc_get_root
    nfs_get_root
    nfs_fs_mount_common
    nfs_try_mount
    nfs_fs_mount
    mount_fs
    vfs_kern_mount
    do_mount
    sys_mount
    do_mount_root
    mount_root
    prepare_namespace
    kernel_init_freeable
    kernel_init

Although the rootfs mounts, the system is unstable.  Here's a transcript
from a PM test:

  http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt

Here's what the test log should look like:

  http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt

Mailing list discussion is here:

  http://lkml.org/lkml/2013/3/4/221

Deal with this for v3.9 by reverting the problem commit, until folks can
figure out the right long-term course of action.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: <maciej.rutecki@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ben Chan <benchan@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-31 11:38:33 -07:00
Mandeep Singh Baines 6aa9707099 lockdep: check that no locks held at freeze time
We shouldn't try_to_freeze if locks are held.  Holding a lock can cause a
deadlock if the lock is later acquired in the suspend or hibernate path
(e.g.  by dpm).  Holding a lock can also cause a deadlock in the case of
cgroup_freezer if a lock is held inside a frozen cgroup that is later
acquired by a process outside that group.

[akpm@linux-foundation.org: export debug_check_no_locks_held]
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ben Chan <benchan@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:11 -08:00
Li Fei 957d1282bb suspend: enable freeze timeout configuration through sys
At present, the value of timeout for freezing is 20s, which is
meaningless in case that one thread is frozen with mutex locked
and another thread is trying to lock the mutex, as this time of
freezing will fail unavoidably.
And if there is no new wakeup event registered, the system will
waste at most 20s for such meaningless trying of freezing.

With this patch, the value of timeout can be configured to smaller
value, so such meaningless trying of freezing will be aborted in
earlier time, and later freezing can be also triggered in earlier
time. And more power will be saved.
In normal case on mobile phone, it costs real little time to freeze
processes. On some platform, it only costs about 20ms to freeze
user space processes and 10ms to freeze kernel freezable threads.

Signed-off-by: Liu Chuansheng <chuansheng.liu@intel.com>
Signed-off-by: Li Fei <fei.li@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-09 22:32:48 +01:00
Linus Torvalds d206e09036 Merge branch 'for-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup changes from Tejun Heo:
 "A lot of activities on cgroup side.  The big changes are focused on
  making cgroup hierarchy handling saner.

   - cgroup_rmdir() had peculiar semantics - it allowed cgroup
     destruction to be vetoed by individual controllers and tried to
     drain refcnt synchronously.  The vetoing never worked properly and
     caused good deal of contortions in cgroup.  memcg was the last
     reamining user.  Michal Hocko removed the usage and cgroup_rmdir()
     path has been simplified significantly.  This was done in a
     separate branch so that the memcg people can base further memcg
     changes on top.

   - The above allowed cleaning up cgroup lifecycle management and
     implementation of generic cgroup iterators which are used to
     improve hierarchy support.

   - cgroup_freezer updated to allow migration in and out of a frozen
     cgroup and handle hierarchy.  If a cgroup is frozen, all descendant
     cgroups are frozen.

   - netcls_cgroup and netprio_cgroup updated to handle hierarchy
     properly.

   - Various fixes and cleanups.

   - Two merge commits.  One to pull in memcg and rmdir cleanups (needed
     to build iterators).  The other pulled in cgroup/for-3.7-fixes for
     device_cgroup fixes so that further device_cgroup patches can be
     stacked on top."

Fixed up a trivial conflict in mm/memcontrol.c as per Tejun (due to
commit bea8c150a7 ("memcg: fix hotplugged memory zone oops") in master
touching code close to commit 2ef37d3fe4 ("memcg: Simplify
mem_cgroup_force_empty_list error handling") in for-3.8)

* 'for-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (65 commits)
  cgroup: update Documentation/cgroups/00-INDEX
  cgroup_rm_file: don't delete the uncreated files
  cgroup: remove subsystem files when remounting cgroup
  cgroup: use cgroup_addrm_files() in cgroup_clear_directory()
  cgroup: warn about broken hierarchies only after css_online
  cgroup: list_del_init() on removed events
  cgroup: fix lockdep warning for event_control
  cgroup: move list add after list head initilization
  netprio_cgroup: allow nesting and inherit config on cgroup creation
  netprio_cgroup: implement netprio[_set]_prio() helpers
  netprio_cgroup: use cgroup->id instead of cgroup_netprio_state->prioidx
  netprio_cgroup: reimplement priomap expansion
  netprio_cgroup: shorten variable names in extend_netdev_table()
  netprio_cgroup: simplify write_priomap()
  netcls_cgroup: move config inheritance to ->css_online() and remove .broken_hierarchy marking
  cgroup: remove obsolete guarantee from cgroup_task_migrate.
  cgroup: add cgroup->id
  cgroup, cpuset: remove cgroup_subsys->post_clone()
  cgroup: s/CGRP_CLONE_CHILDREN/CGRP_CPUSET_CLONE_CHILDREN/
  cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()
  ...
2012-12-12 08:18:24 -08:00
Li Haifeng e5f5762177 PM / Freezer: Fixup compile error of try_to_freeze_nowarn()
If FREEZER is not defined, the error as following will be throw
when compiled.
arch/arm/kernel/signal.c:645: error: implicit declaration of function
'try_to_freeze_nowarn'

Signed-off-by: Haifeng Li <omycle@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-23 21:55:19 +01:00
Oleg Nesterov 5d8f72b55c freezer: change ptrace_stop/do_signal_stop to use freezable_schedule()
try_to_freeze_tasks() and cgroup_freezer rely on scheduler locks
to ensure that a task doing STOPPED/TRACED -> RUNNING transition
can't escape freezing. This mostly works, but ptrace_stop() does
not necessarily call schedule(), it can change task->state back to
RUNNING and check freezing() without any lock/barrier in between.

We could add the necessary barrier, but this patch changes
ptrace_stop() and do_signal_stop() to use freezable_schedule().
This fixes the race, freezer_count() and freezer_should_skip()
carefully avoid the race.

And this simplifies the code, try_to_freeze_tasks/update_if_frozen
no longer need to use task_is_stopped_or_traced() checks with the
non trivial assumptions. We can rely on the mechanism which was
specially designed to mark the sleeping task as "frozen enough".

v2: As Tejun pointed out, we can also change get_signal_to_deliver()
and move try_to_freeze() up before 'relock' label.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2012-10-26 14:27:49 -07:00
Tejun Heo dd67d32dbc freezer: add missing mb's to freezer_count() and freezer_should_skip()
A task is considered frozen enough between freezer_do_not_count() and
freezer_count() and freezers use freezer_should_skip() to test this
condition.  This supposedly works because freezer_count() always calls
try_to_freezer() after clearing %PF_FREEZER_SKIP.

However, there currently is nothing which guarantees that
freezer_count() sees %true freezing() after clearing %PF_FREEZER_SKIP
when freezing is in progress, and vice-versa.  A task can escape the
freezing condition in effect by freezer_count() seeing !freezing() and
freezer_should_skip() seeing %PF_FREEZER_SKIP.

This patch adds smp_mb()'s to freezer_count() and
freezer_should_skip() such that either %true freezing() is visible to
freezer_count() or !PF_FREEZER_SKIP is visible to
freezer_should_skip().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@vger.kernel.org
2012-10-16 15:03:14 -07:00
Rafael J. Wysocki 181e9bdef3 PM / Hibernate: Fix s2disk regression related to freezing workqueues
Commit 2aede851dd

  PM / Hibernate: Freeze kernel threads after preallocating memory

introduced a mechanism by which kernel threads were frozen after
the preallocation of hibernate image memory to avoid problems with
frozen kernel threads not responding to memory freeing requests.
However, it overlooked the s2disk code path in which the
SNAPSHOT_CREATE_IMAGE ioctl was run directly after SNAPSHOT_FREE,
which caused freeze_workqueues_begin() to BUG(), because it saw
that worqueues had been already frozen.

Although in principle this issue might be addressed by removing
the relevant BUG_ON() from freeze_workqueues_begin(), that would
reintroduce the very problem that commit 2aede851dd
attempted to avoid into that particular code path.  For this reason,
to fix the issue at hand, introduce thaw_kernel_threads() and make
the SNAPSHOT_FREE ioctl execute it.

Special thanks to Srivatsa S. Bhat for detailed analysis of the
problem.

Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: stable@kernel.org
2012-01-29 20:35:52 +01:00
Jeff Layton b3b73ec0d7 PM / Freezer: fix return value of freezable_schedule_timeout_killable()
...it should return the return code from schedule_timeout_killable(),
not the one from freezer_count().

All of the current callers ignore the return code so the bug is
harmless but it's worth fixing.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-27 01:06:33 +01:00
Srivatsa S. Bhat 467de1fc67 PM / Freezer: Remove the "userspace only" constraint from freezer[_do_not]_count()
At present, the functions freezer_count() and freezer_do_not_count()
impose the restriction that they are effective only for userspace processes.
However, now, these functions have found more utility than originally
intended by the commit which introduced it: ba96a0c8 (freezer:
fix vfork problem). And moreover, even the vfork issue actually does not
need the above restriction in these functions.

So, modify these functions to make them work even for kernel threads, so
that they can be used at other places in the kernel, where the userspace
restriction doesn't apply.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-08 23:21:01 +01:00
Jeff Layton d310310cbf Freezer / sunrpc / NFS: don't allow TASK_KILLABLE sleeps to block the freezer
Allow the freezer to skip wait_on_bit_killable sleeps in the sunrpc
layer. This should allow suspend and hibernate events to proceed, even
when there are RPC's pending on the wire.

Also, wrap the TASK_KILLABLE sleeps in NFS layer in freezer_do_not_count
and freezer_count calls. This allows the freezer to skip tasks that are
sleeping while looping on EJUKEBOX or NFS4ERR_DELAY sorts of errors.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-12-06 22:12:27 +01:00
Stephen Rothwell 62c9ea6b12 Freezer: fix more fallout from the thaw_process rename
Commit 944e192db53c "freezer: rename thaw_process() to __thaw_task()
and simplify the implementation" did not create a !CONFIG_FREEZER version
of __thaw_task().

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-25 00:44:55 +01:00
Oleg Nesterov 24b7ead3fb freezer: fix wait_event_freezable/__thaw_task races
wait_event_freezable() and friends stop the waiting if try_to_freeze()
fails. This is not right, we can race with __thaw_task() and in this
case

	- wait_event_freezable() returns the wrong ERESTARTSYS

	- wait_event_freezable_timeout() can return the positive
	  value while condition == F

Change the code to always check __retval/condition before return.

Note: with or without this patch the timeout logic looks strange,
probably we should recalc timeout if try_to_freeze() returns T.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
2011-11-23 09:28:17 -08:00
Tejun Heo 34b087e483 freezer: kill unused set_freezable_with_signal()
There's no in-kernel user of set_freezable_with_signal() left.  Mixing
TIF_SIGPENDING with kernel threads can lead to nasty corner cases as
kernel threads never travel signal delivery path on their own.

e.g. the current implementation is buggy in the cancelation path of
__thaw_task().  It calls recalc_sigpending_and_wake() in an attempt to
clear TIF_SIGPENDING but the function never clears it regardless of
sigpending state.  This means that signallable freezable kthreads may
continue executing with !freezing() && stuck TIF_SIGPENDING, which can
be troublesome.

This patch removes set_freezable_with_signal() along with
PF_FREEZER_NOSIG and recalc_sigpending*() calls in freezer.  User
tasks get TIF_SIGPENDING, kernel tasks get woken up and the spurious
sigpending is dealt with in the usual signal delivery path.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
2011-11-23 09:28:17 -08:00
Tejun Heo 839e3407d9 freezer: remove unused @sig_only from freeze_task()
After "freezer: make freezing() test freeze conditions in effect
instead of TIF_FREEZE", freezing() returns authoritative answer on
whether the current task should freeze or not and freeze_task()
doesn't need or use @sig_only.  Remove it.

While at it, rewrite function comment for freeze_task() and rename
@sig_only to @user_only in try_to_freeze_tasks().

This patch doesn't cause any functional change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
2011-11-21 12:32:26 -08:00
Tejun Heo 96ee6d8539 freezer: fix set_freezable[_with_signal]() race
A kthread doing set_freezable*() may race with on-going PM freeze and
the freezer might think all tasks are frozen while the new freezable
kthread is merrily proceeding to execute code paths which aren't
supposed to be executing during PM freeze.

Reimplement set_freezable[_with_signal]() using __set_freezable() such
that freezable PF flags are modified under freezer_lock and
try_to_freeze() is called afterwards.  This eliminates race condition
against freezing.

Note: Separated out from larger patch to resolve fix order dependency
      Oleg pointed out.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
2011-11-21 12:32:25 -08:00
Tejun Heo 948246f70a freezer: remove should_send_signal() and update frozen()
should_send_signal() is only used in freezer.c.  Exporting them only
increases chance of abuse.  Open code the two users and remove it.

Update frozen() to return bool.

Signed-off-by: Tejun Heo <tj@kernel.org>
2011-11-21 12:32:25 -08:00
Tejun Heo a3201227f8 freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
Using TIF_FREEZE for freezing worked when there was only single
freezing condition (the PM one); however, now there is also the
cgroup_freezer and single bit flag is getting clumsy.
thaw_processes() is already testing whether cgroup freezing in in
effect to avoid thawing tasks which were frozen by both PM and cgroup
freezers.

This is racy (nothing prevents race against cgroup freezing) and
fragile.  A much simpler way is to test actual freeze conditions from
freezing() - ie. directly test whether PM or cgroup freezing is in
effect.

This patch adds variables to indicate whether and what type of
freezing conditions are in effect and reimplements freezing() such
that it directly tests whether any of the two freezing conditions is
active and the task should freeze.  On fast path, freezing() is still
very cheap - it only tests system_freezing_cnt.

This makes the clumsy dancing aroung TIF_FREEZE unnecessary and
freeze/thaw operations more usual - updating state variables for the
new state and nudging target tasks so that they notice the new state
and comply.  As long as the nudging happens after state update, it's
race-free.

* This allows use of freezing() in freeze_task().  Replace the open
  coded tests with freezing().

* p != current test is added to warning printing conditions in
  try_to_freeze_tasks() failure path.  This is necessary as freezing()
  is now true for the task which initiated freezing too.

-v2: Oleg pointed out that re-freezing FROZEN cgroup could increment
     system_freezing_cnt.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Paul Menage <paul@paulmenage.org>  (for the cgroup portions)
2011-11-21 12:32:25 -08:00
Tejun Heo 22b4e111fa cgroup_freezer: prepare for removal of TIF_FREEZE
TIF_FREEZE will be removed soon and freezing() will directly test
whether any freezing condition is in effect.  Make the following
changes in preparation.

* Rename cgroup_freezing_or_frozen() to cgroup_freezing() and make it
  return bool.

* Make cgroup_freezing() access task_freezer() under rcu read lock
  instead of task_lock().  This makes the state dereferencing racy
  against task moving to another cgroup; however, it was already racy
  without this change as ->state dereference wasn't synchronized.
  This will be later dealt with using attach hooks.

* freezer->state is now set before trying to push tasks into the
  target state.

-v2: Oleg pointed out that freeze_change_state() was setting
     freeze->state incorrectly to CGROUP_FROZEN instead of
     CGROUP_FREEZING.  Fixed.

-v3: Matt pointed out that setting CGROUP_FROZEN used to always invoke
     try_to_freeze_cgroup() regardless of the current state.  Patch
     updated such that the actual freeze/thaw operations are always
     performed on invocation.  This shouldn't make any difference
     unless something is broken.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
2011-11-21 12:32:25 -08:00
Tejun Heo 03afed8bc2 freezer: clean up freeze_processes() failure path
freeze_processes() failure path is rather messy.  Freezing is canceled
for workqueues and tasks which aren't frozen yet but frozen tasks are
left alone and should be thawed by the caller and of course some
callers (xen and kexec) didn't do it.

This patch updates __thaw_task() to handle cancelation correctly and
makes freeze_processes() and freeze_kernel_threads() call
thaw_processes() on failure instead so that the system is fully thawed
on failure.  Unnecessary [suspend_]thaw_processes() calls are removed
from kernel/power/hibernate.c, suspend.c and user.c.

While at it, restructure error checking if clause in suspend_prepare()
to be less weird.

-v2: Srivatsa spotted missing removal of suspend_thaw_processes() in
     suspend_prepare() and error in commit message.  Updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
2011-11-21 12:32:24 -08:00
Tejun Heo a5be2d0d1a freezer: rename thaw_process() to __thaw_task() and simplify the implementation
thaw_process() now has only internal users - system and cgroup
freezers.  Remove the unnecessary return value, rename, unexport and
collapse __thaw_process() into it.  This will help further updates to
the freezer code.

-v3: oom_kill grew a use of thaw_process() while this patch was
     pending.  Convert it to use __thaw_task() for now.  In the longer
     term, this should be handled by allowing tasks to die if killed
     even if it's frozen.

-v2: minor style update as suggested by Matt.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Paul Menage <menage@google.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
2011-11-21 12:32:23 -08:00
Tejun Heo 8a32c441c1 freezer: implement and use kthread_freezable_should_stop()
Writeback and thinkpad_acpi have been using thaw_process() to prevent
deadlock between the freezer and kthread_stop(); unfortunately, this
is inherently racy - nothing prevents freezing from happening between
thaw_process() and kthread_stop().

This patch implements kthread_freezable_should_stop() which enters
refrigerator if necessary but is guaranteed to return if
kthread_stop() is invoked.  Both thaw_process() users are converted to
use the new function.

Note that this deadlock condition exists for many of freezable
kthreads.  They need to be converted to use the new should_stop or
freezable workqueue.

Tested with synthetic test case.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
2011-11-21 12:32:23 -08:00
Tejun Heo a0acae0e88 freezer: unexport refrigerator() and update try_to_freeze() slightly
There is no reason to export two functions for entering the
refrigerator.  Calling refrigerator() instead of try_to_freeze()
doesn't save anything noticeable or removes any race condition.

* Rename refrigerator() to __refrigerator() and make it return bool
  indicating whether it scheduled out for freezing.

* Update try_to_freeze() to return bool and relay the return value of
  __refrigerator() if freezing().

* Convert all refrigerator() users to try_to_freeze().

* Update documentation accordingly.

* While at it, add might_sleep() to try_to_freeze().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: Christoph Hellwig <hch@infradead.org>
2011-11-21 12:32:22 -08:00
Oleg Nesterov 6f35c4abd7 PM / Freezer: Reimplement wait_event_freezekillable using freezer_do_not_count/freezer_count
Commit 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake
TASK_KILLABLE tasks too" updated fake_signal_wake_up() used by freezer
to wake up KILLABLE tasks.  Sending unsolicited wakeups to tasks in
killable sleep is dangerous as there are code paths which depend on
tasks not waking up spuriously from KILLABLE sleep.

For example. sys_read() or page can sleep in TASK_KILLABLE assuming
that wait/down/whatever _killable can only fail if we can not return
to the usermode.  TASK_TRACED is another obvious example.

The offending commit was to resolve freezer hang during system PM
operations caused by KILLABLE sleeps in network filesystems.
wait_event_freezekillable(), which depends on the spurious KILLABLE
wakeup, was added by f06ac72e92 "cifs, freezer: add
wait_event_freezekillable and have cifs use it" to be used to
implement killable & freezable sleeps in network filesystems.

To prepare for reverting of 27920651fe, this patch reimplements
wait_event_freezekillable() using freezer_do_not_count/freezer_count()
so that it doesn't depend on the spurious KILLABLE wakeup.  This isn't
very nice but should do for now.

[tj: Refreshed patch to apply to linus/master and updated commit
    description on Rafael's request.]

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-11-04 22:28:15 +01:00
Linus Torvalds dabcbb1bae Merge branch '3.2-without-smb2' of git://git.samba.org/sfrench/cifs-2.6
* '3.2-without-smb2' of git://git.samba.org/sfrench/cifs-2.6: (52 commits)
  Fix build break when freezer not configured
  Add definition for share encryption
  CIFS: Make cifs_push_locks send as many locks at once as possible
  CIFS: Send as many mandatory unlock ranges at once as possible
  CIFS: Implement caching mechanism for posix brlocks
  CIFS: Implement caching mechanism for mandatory brlocks
  CIFS: Fix DFS handling in cifs_get_file_info
  CIFS: Fix error handling in cifs_readv_complete
  [CIFS] Fixup trivial checkpatch warning
  [CIFS] Show nostrictsync and noperm mount options in /proc/mounts
  cifs, freezer: add wait_event_freezekillable and have cifs use it
  cifs: allow cifs_max_pending to be readable under /sys/module/cifs/parameters
  cifs: tune bdi.ra_pages in accordance with the rsize
  cifs: allow for larger rsize= options and change defaults
  cifs: convert cifs_readpages to use async reads
  cifs: add cifs_async_readv
  cifs: fix protocol definition for READ_RSP
  cifs: add a callback function to receive the rest of the frame
  cifs: break out 3rd receive phase into separate function
  cifs: find mid earlier in receive codepath
  ...
2011-10-28 10:43:32 -07:00
Steve French e0c8ea1a69 Fix build break when freezer not configured
fs/cifs/transport.c: In function 'wait_for_response':
fs/cifs/transport.c:328: error: implicit declaration of function 'wait_event_freezekillable'

Caused by commit f06ac72e92 ("cifs, freezer: add
wait_event_freezekillable and have cifs use it").  In this config,
CONFIG_FREEZER is not set.

Reviewed-by: Shirish Pargaonkar <shirishp@us.ibm.com>
CC: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2011-10-27 16:53:40 -05:00
Steve French b957ae9c53 [CIFS] Fixup trivial checkpatch warning
Signed-off-by: Steve French <smfrench@gmail.com>
2011-10-19 21:27:11 -05:00
Jeff Layton f06ac72e92 cifs, freezer: add wait_event_freezekillable and have cifs use it
CIFS currently uses wait_event_killable to put tasks to sleep while
they await replies from the server. That function though does not
allow the freezer to run. In many cases, the network interface may
be going down anyway, in which case the reply will never come. The
client then ends up blocking the computer from suspending.

Fix this by adding a new wait_event_freezable variant --
wait_event_freezekillable. The idea is to combine the behavior of
wait_event_killable and wait_event_freezable -- put the task to
sleep and only allow it to be awoken by fatal signals, but also
allow the freezer to do its job.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
2011-10-19 15:30:40 -04:00
Rafael J. Wysocki 2aede851dd PM / Hibernate: Freeze kernel threads after preallocating memory
There is a problem with the current ordering of hibernate code which
leads to deadlocks in some filesystems' memory shrinkers.  Namely,
some filesystems use freezable kernel threads that are inactive when
the hibernate memory preallocation is carried out.  Those same
filesystems use memory shrinkers that may be triggered by the
hibernate memory preallocation.  If those memory shrinkers wait for
the frozen kernel threads, the hibernate process deadlocks (this
happens with XFS, for one example).

Apparently, it is not technically viable to redesign the filesystems
in question to avoid the situation described above, so the only
possible solution of this issue is to defer the freezing of kernel
threads until the hibernate memory preallocation is done, which is
implemented by this change.

Unfortunately, this requires the memory preallocation to be done
before the "prepare" stage of device freeze, so after this change the
only way drivers can allocate additional memory for their freeze
routines in a clean way is to use PM notifiers.

Reported-by: Christoph <cr2005@u-club.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-10-16 23:28:52 +02:00
Tejun Heo 58a69cb47e workqueue, freezer: unify spelling of 'freeze' + 'able' to 'freezable'
There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'.  The former is the more prominent one.  The latter is
mostly used by workqueue and in a few other odd places.  Unify the
spelling to 'freezable'.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
2011-02-16 17:48:59 +01:00
Matt Helsley 5a7aadfe2f 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>
2010-03-26 23:51:44 +01:00
Li Zefan 00c2e63c31 freezer_cg: use thaw_process() in unfreeze_cgroup()
Don't duplicate the implementation of thaw_process().

[akpm@linux-foundation.org: make __thaw_process() static]
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-30 11:38:45 -07:00
Matt Helsley dc52ddc0e6 container freezer: implement freezer cgroup subsystem
This patch implements a new freezer subsystem in the control groups
framework.  It provides a way to stop and resume execution of all tasks in
a cgroup by writing in the cgroup filesystem.

The freezer subsystem in the container filesystem defines a file named
freezer.state.  Writing "FROZEN" to the state file will freeze all tasks
in the cgroup.  Subsequently writing "RUNNING" will unfreeze the tasks in
the cgroup.  Reading will return the current state.

* Examples of usage :

   # mkdir /containers/freezer
   # mount -t cgroup -ofreezer freezer  /containers
   # mkdir /containers/0
   # echo $some_pid > /containers/0/tasks

to get status of the freezer subsystem :

   # cat /containers/0/freezer.state
   RUNNING

to freeze all tasks in the container :

   # echo FROZEN > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   FREEZING
   # cat /containers/0/freezer.state
   FROZEN

to unfreeze all tasks in the container :

   # echo RUNNING > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   RUNNING

This is the basic mechanism which should do the right thing for user space
task in a simple scenario.

It's important to note that freezing can be incomplete.  In that case we
return EBUSY.  This means that some tasks in the cgroup are busy doing
something that prevents us from completely freezing the cgroup at this
time.  After EBUSY, the cgroup will remain partially frozen -- reflected
by freezer.state reporting "FREEZING" when read.  The state will remain
"FREEZING" until one of these things happens:

	1) Userspace cancels the freezing operation by writing "RUNNING" to
		the freezer.state file
	2) Userspace retries the freezing operation by writing "FROZEN" to
		the freezer.state file (writing "FREEZING" is not legal
		and returns EIO)
	3) The tasks that blocked the cgroup from entering the "FROZEN"
		state disappear from the cgroup's set of tasks.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: export thaw_process]
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:34 -07:00
Matt Helsley 8174f1503f container freezer: make refrigerator always available
Now that the TIF_FREEZE flag is available in all architectures, extract
the refrigerator() and freeze_task() from kernel/power/process.c and make
it available to all.

The refrigerator() can now be used in a control group subsystem
implementing a control group freezer.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Matt Helsley <matthltc@us.ibm.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Matt Helsley <matthltc@us.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:33 -07:00
Rafael J. Wysocki ebb12db51f Freezer: Introduce PF_FREEZER_NOSIG
The freezer currently attempts to distinguish kernel threads from
user space tasks by checking if their mm pointer is unset and it
does not send fake signals to kernel threads.  However, there are
kernel threads, mostly related to networking, that behave like
user space tasks and may want to be sent a fake signal to be frozen.

Introduce the new process flag PF_FREEZER_NOSIG that will be set
by default for all kernel threads and make the freezer only send
fake signals to the tasks having PF_FREEZER_NOSIG unset.  Provide
the set_freezable_with_signal() function to be called by the kernel
threads that want to be sent a fake signal for freezing.

This patch should not change the freezer's observable behavior.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Len Brown <len.brown@intel.com>
2008-07-16 23:27:03 +02:00
Rafael J. Wysocki e42837bcd3 freezer: introduce freezer-friendly waiting macros
Introduce freezer-friendly wrappers around wait_event_interruptible() and
wait_event_interruptible_timeout(), originally defined in <linux/wait.h>, to
be used in freezable kernel threads.  Make some of the freezable kernel
threads use them.

This is necessary for the freezer to stop sending signals to kernel threads,
which is implemented in the next patch.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-18 14:37:19 -07:00
Rafael J. Wysocki 296699de6b Introduce CONFIG_SUSPEND for suspend-to-Ram and standby
Introduce CONFIG_SUSPEND representing the ability to enter system sleep
states, such as the ACPI S3 state, and allow the user to choose SUSPEND
and HIBERNATION independently of each other.

Make HOTPLUG_CPU be selected automatically if SUSPEND or HIBERNATION has
been chosen and the kernel is intended for SMP systems.

Also, introduce CONFIG_PM_SLEEP which is automatically selected if
CONFIG_SUSPEND or CONFIG_HIBERNATION is set and use it to select the
code needed for both suspend and hibernation.

The top-level power management headers and the ACPI code related to
suspend and hibernation are modified to use the new definitions (the
changes in drivers/acpi/sleep/main.c are, mostly, moving code to reduce
the number of ifdefs).

There are many other files in which CONFIG_PM can be replaced with
CONFIG_PM_SLEEP or even with CONFIG_SUSPEND, but they can be updated in
the future.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-29 16:45:38 -07:00
Rafael J. Wysocki 0c1eecfb34 Freezer: avoid freezing kernel threads prematurely
Kernel threads should not have TIF_FREEZE set when user space processes are
being frozen, since otherwise some of them might be frozen prematurely.
To prevent this from happening we can (1) make exit_mm() unset TIF_FREEZE
unconditionally just after clearing tsk->mm and (2) make try_to_freeze_tasks()
check if p->mm is different from zero and PF_BORROWED_MM is unset in p->flags
when user space processes are to be frozen.

Namely, when user space processes are being frozen, we only should set
TIF_FREEZE for tasks that have p->mm different from NULL and don't have
PF_BORROWED_MM set in p->flags.  For this reason task_lock() must be used to
prevent try_to_freeze_tasks() from racing with use_mm()/unuse_mm(), in which
p->mm and p->flags.PF_BORROWED_MM are changed under task_lock(p).  Also, we
need to prevent the following scenario from happening:

* daemonize() is called by a task spawned from a user space code path
* freezer checks if the task has p->mm set and the result is positive
* task enters exit_mm() and clears its TIF_FREEZE
* freezer sets TIF_FREEZE for the task
* task calls try_to_freeze() and goes to the refrigerator, which is wrong at
  that point

This requires us to acquire task_lock(p) before p->flags.PF_BORROWED_MM and
p->mm are examined and release it after TIF_FREEZE is set for p (or it turns
out that TIF_FREEZE should not be set).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:42 -07:00