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* 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc: (24 commits)
freezer: fix wait_event_freezable/__thaw_task races
freezer: kill unused set_freezable_with_signal()
dmatest: don't use set_freezable_with_signal()
usb_storage: don't use set_freezable_with_signal()
freezer: remove unused @sig_only from freeze_task()
freezer: use lock_task_sighand() in fake_signal_wake_up()
freezer: restructure __refrigerator()
freezer: fix set_freezable[_with_signal]() race
freezer: remove should_send_signal() and update frozen()
freezer: remove now unused TIF_FREEZE
freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
cgroup_freezer: prepare for removal of TIF_FREEZE
freezer: clean up freeze_processes() failure path
freezer: kill PF_FREEZING
freezer: test freezable conditions while holding freezer_lock
freezer: make freezing indicate freeze condition in effect
freezer: use dedicated lock instead of task_lock() + memory barrier
freezer: don't distinguish nosig tasks on thaw
freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
freezer: rename thaw_process() to __thaw_task() and simplify the implementation
...
The hibernation core code forgets to release memory preallocated
for hibernation if there's an error in its early stages or if test
modes causing hibernation_snapshot() to return early are used. This
causes the system to be hardly usable, because the amount of
preallocated memory is usually huge. Fix this problem.
Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (31 commits)
drm: integer overflow in drm_mode_dirtyfb_ioctl()
drivers/gpu/vga/vgaarb.c: add missing kfree
drm/radeon/kms/atom: unify i2c gpio table handling
drm/radeon/kms: fix up gpio i2c mask bits for r4xx for real
ttm: Don't return the bo reserved on error path
drm/radeon/kms: add a CS ioctl flag not to rewrite tiling flags in the CS
drm/i915: Fix inconsistent backlight level during disabled
drm, i915: Fix memory leak in i915_gem_busy_ioctl().
drm/i915: Use DPCD value for max DP lanes.
drm/i915: Initiate DP link training only on the lanes we'll be using
drm/i915: Remove trailing white space
drm/i915: Try harder during dp pattern 1 link training
drm/i915: Make DP prepare/commit consistent with DP dpms
drm/i915: Let panel power sequencing hardware do its job
drm/i915: Treat PCH eDP like DP in most places
drm/i915: Remove link_status field from intel_dp structure
drm/i915: Move common PCH_PP_CONTROL setup to ironlake_get_pp_control
drm/i915: Module parameters using '-1' as default must be signed type
drm/i915: Turn on another required clock gating bit on gen6.
drm/i915: Turn on a required 3D clock gating bit on Sandybridge.
...
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>
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>
Commit 981ed70d8e (dmatest: make dmatest threads freezable) made
dmatest kthread use set_freezable_with_signal(); however, the
interface is scheduled to be removed in the next merge window.
The problem is that unlike userland tasks there's no default place
which handles signal pending state and it isn't clear who owns and/or
is responsible for clearing TIF_SIGPENDING. For example, in the
current code, try_to_freeze() clears TIF_SIGPENDING but it isn't sure
whether it actually owns the TIF_SIGPENDING nor is it race-free -
ie. the task may continue to run with TIF_SIGPENDING set after the
freezable section.
Unfortunately, we don't have wait_for_completion_freezable_timeout().
This patch open codes it and uses wait_event_freezable_timeout()
instead and removes timeout reloading - wait_event_freezable_timeout()
won't return across freezing events (currently racy but fix scheduled)
and timer doesn't decrement while the task is in freezer. Although
this does lose timer-reset-over-freezing, given that timeout is
supposed to be long enough and failure to finish inside is considered
irrecoverable, I don't think this is worth the complexity.
While at it, move completion to outer scope and explain that we're
ignoring dangling pointer problem after timeout. This should give
slightly better chance at avoiding oops after timeout.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Count of selector voltage is required for regulator_set_voltage
to work via set_voltage_sel. VDD1/2 currently have it as zero,
so regulator_set_voltage won't work for VDD1/2.
Update count (n_voltages) for VDD1/2.
Output Voltage = (step value * 12.5 mV + 562.5 mV) * gain
With above expr, number of voltages that can be selected is
step value count * gain count
constant for gain count will be called VDD1_2_NUM_VOLT_COARSE
existing constant for step value count is VDD1_2_NUM_VOLTS,
use VDD1_2_NUM_VOLT_FINE instead to make clear that step value
is not the only component in deciding selectable voltage count
Signed-off-by: Afzal Mohammed <afzal@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
The function i2cdev_notifier_call is used only in i2c-dev file
making it static.
Also removes the following sparse warning
drivers/i2c/i2c-dev.c:582:5: warning: symbol 'i2cdev_notifier_call'
was not declared. Should it be static?
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Last piece of code using ANY_I2C_BUS was deleted almost 2 years ago,
so ANY_I2C_BUS can go away as well.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
10-bit addresses overlap with traditional 7-bit addresses, leading in
device name collisions. Add an arbitrary offset to 10-bit addresses to
prevent this collision. The offset was chosen so that the address is
still easily recognizable.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
The wrong bits were put on the wire, fix that.
This fixes kernel bug #42562.
Signed-off-by: Sheng-Hui J. Chu <jeffchu@broadcom.com>
Cc: stable@kernel.org
Signed-off-by: Jean Delvare <khali@linux-fr.org>
There is a potential integer overflow in drm_mode_dirtyfb_ioctl()
if userspace passes in a large num_clips. The call to kmalloc would
allocate a small buffer, and the call to fb->funcs->dirty may result
in a memory corruption.
Reported-by: Haogang Chen <haogangchen@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This reverts commit dc93728084.
As requested by Ben Herrenschmidt:
"This breaks some powerpc platforms at least. The practice of having
a node provide an explicit "interrupt-parent" property pointing to
itself is an old trick that we've used in the past to allow a
device-node to have interrupts routed to different controllers.
In that case, the node also contains an interrupt-map, so the node is
its own parent, the interrupt resolution hits the map, which then can
route each individual interrupt to a different parent."
Grant says:
"Ah, nuts, yes that is broken then. Yes, please revert the commit and
Rob & I will come up with a better solution.
Rob, I think it can be done by explicitly checking for np ==
desc->interrupt_parent in of_irq_init() instead of relying on
of_irq_find_parent() returning NULL."
Requested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: Tanmay Inamdar <tinamdar@apm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
mount_subtree() pointless use-after-free
iio: fix a leak due to improper use of anon_inode_getfd()
microblaze: bury asm/namei.h
kbuf is a buffer that is local to this function, so all of the error paths
leaving the function should release it.
Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Split the quirks and i2c_rec assignment into separate
functions used by both radeon_lookup_i2c_gpio() and
radeon_atombios_i2c_init(). This avoids duplicating code
and cases where quirks were only added to one of the
functions.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Fixes i2c test failures when i2c_algo_bit.bit_test=1.
The hw doesn't actually require a mask, so just set it
to the default mask bits for r1xx-r4xx radeon ddc.
I missed this part the first time through.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
An unlikely race could case a bo to be returned reserved on an error path.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
* 'drm-intel-fixes' of git://people.freedesktop.org/~keithp/linux: (25 commits)
drm/i915: Fix inconsistent backlight level during disabled
drm, i915: Fix memory leak in i915_gem_busy_ioctl().
drm/i915: Use DPCD value for max DP lanes.
drm/i915: Initiate DP link training only on the lanes we'll be using
drm/i915: Remove trailing white space
drm/i915: Try harder during dp pattern 1 link training
drm/i915: Make DP prepare/commit consistent with DP dpms
drm/i915: Let panel power sequencing hardware do its job
drm/i915: Treat PCH eDP like DP in most places
drm/i915: Remove link_status field from intel_dp structure
drm/i915: Move common PCH_PP_CONTROL setup to ironlake_get_pp_control
drm/i915: Module parameters using '-1' as default must be signed type
drm/i915: Turn on another required clock gating bit on gen6.
drm/i915: Turn on a required 3D clock gating bit on Sandybridge.
drm/i915: enable cacheable objects on Ivybridge
drm/i915: add constants to size fence arrays and fields
drm/i915: Ivybridge still has fences!
drm/i915: forcewake warning fixes in debugfs
drm/i915: Fix object refcount leak on mmappable size limit error path.
drm/i915: Use mode_config.mutex in ironlake_panel_vdd_work
...
d'oh... we'd carefully pinned mnt->mnt_sb down, dropped mnt and attempt
to grab s_umount on mnt->mnt_sb. The trouble is, *mnt might've been
overwritten by now...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
NFS: Revert pnfs ugliness from the generic NFS read code path
SUNRPC: destroy freshly allocated transport in case of sockaddr init error
NFS: Fix a regression in the referral code
nfs: move nfs_file_operations declaration to bottom of file.c (try #2)
nfs: when attempting to open a directory, fall back on normal lookup (try #5)
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
Btrfs: remove free-space-cache.c WARN during log replay
Btrfs: sectorsize align offsets in fiemap
Btrfs: clear pages dirty for io and set them extent mapped
Btrfs: wait on caching if we're loading the free space cache
Btrfs: prefix resize related printks with btrfs:
btrfs: fix stat blocks accounting
Btrfs: avoid unnecessary bitmap search for cluster setup
Btrfs: fix to search one more bitmap for cluster setup
btrfs: mirror_num should be int, not u64
btrfs: Fix up 32/64-bit compatibility for new ioctls
Btrfs: fix barrier flushes
Btrfs: fix tree corruption after multi-thread snapshots and inode_cache flush
* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
writeback: remove vm_dirties and task->dirties
writeback: hard throttle 1000+ dd on a slow USB stick
mm: Make task in balance_dirty_pages() killable
* 'staging-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
staging: fix more ET131X build errors
staging: et131x depends on NET
staging: slicoss depends on NET
linux-next: et131x: Fix build error when CONFIG_PM_SLEEP not enabled
* 'usb-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (48 commits)
USB: Fix Corruption issue in USB ftdi driver ftdi_sio.c
USB: option: add PID of Huawei E173s 3G modem
OHCI: final fix for NVIDIA problems (I hope)
USB: option: release new PID for ZTE 3G modem
usb: Netlogic: Fix HC_LENGTH call in ehci-xls.c
USB: storage: ene_ub6250: fix compile warnings
USB: option: add id for 3G dongle Model VT1000 of Viettel
USB: serial: pl2303: rm duplicate id
USB: pch_udc: Change company name OKI SEMICONDUCTOR to LAPIS Semiconductor
USB: pch_udc: Support new device LAPIS Semiconductor ML7831 IOH
usb-storage: Accept 8020i-protocol commands longer than 12 bytes
USB: quirks: adding more quirky webcams to avoid squeaky audio
powerpc/usb: fix type cast for address of ioremap to compatible with 64-bit
USB: at91: at91-ohci: fix set/get power
USB: cdc-acm: Fix disconnect() vs close() race
USB: add quirk for Logitech C600 web cam
USB: EHCI: fix HUB TT scheduling issue with iso transfer
USB: XHCI: resume root hubs when the controller resumes
USB: workaround for bug in old version of GCC
USB: ark3116 initialisation fix
...
* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
TTY: ldisc, wait for ldisc infinitely in hangup
TTY: ldisc, move wait idle to caller
TTY: ldisc, allow waiting for ldisc arbitrarily long
Revert "tty/serial: Prevent drop of DCD on suspend for Tegra UARTs"
RS485: fix inconsistencies in the meaning of some variables
pch_uart: Fix DMA resource leak issue
serial,mfd: Fix CMSPAR setup
tty/serial: Prevent drop of DCD on suspend for Tegra UARTs
pch_uart: Change company name OKI SEMICONDUCTOR to LAPIS Semiconductor
pch_uart: Support new device LAPIS Semiconductor ML7831 IOH
pch_uart: Fix hw-flow control issue
tty: hvc_dcc: Fix duplicate character inputs
jsm: Change maintainership
* 'char-misc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
misc: ad525x_dpot: Fix AD8400 spi transfer size.
pch_phub: Fix MAC address writing issue for LAPIS ML7831
pch_phub: Improve ADE(Address Decode Enable) control
pch_phub: Change company name OKI SEMICONDUCTOR to LAPIS Semiconductor
pch_phub: Support new device LAPIS Semiconductor ML7831 IOH
pcie-gadget-spear: Add "platform:" prefix for platform modalias
MAINTAINERS: add CHAR and MISC driver maintainers
altroot support has been gone for years, along with arch/*/asm/namei.h;
looks like a dummy survivor that sat it out in microblaze tree...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The current implementation of set_freezable_with_signal() is buggy and
tricky to get right. usb-storage is the only user and its use can be
avoided trivially.
All usb-storage wants is to be able to sleep with timeout and get
woken up if freezing() becomes true. This can be trivially
implemented by doing interruptible wait w/ freezing() included in the
wait condition. There's no reason to use set_freezable_with_signal().
Perform interruptible wait on freezing() instead of using
set_freezable_with_signal(), which is scheduled for removal.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
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>
cgroup_freezer calls freeze_task() without holding tasklist_lock and,
if the task is exiting, its ->sighand may be gone by the time
fake_signal_wake_up() is called. Use lock_task_sighand() instead of
accessing ->sighand directly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Paul Menage <paul@paulmenage.org>
If another freeze happens before all tasks leave FROZEN state after
being thawed, the freezer can see the existing FROZEN and consider the
tasks to be frozen but they can clear FROZEN without checking the new
freezing().
Oleg suggested restructuring __refrigerator() such that there's single
condition check section inside freezer_lock and sigpending is cleared
afterwards, which fixes the problem and simplifies the code.
Restructure accordingly.
-v2: Frozen loop exited without releasing freezer_lock. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
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>
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>
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)
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>
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>
With the previous changes, there's no meaningful difference between
PF_FREEZING and PF_FROZEN. Remove PF_FREEZING and use PF_FROZEN
instead in task_contributes_to_load().
Signed-off-by: Tejun Heo <tj@kernel.org>
try_to_freeze_tasks() and thaw_processes() use freezable() and
frozen() as preliminary tests before initiating operations on a task.
These are done without any synchronization and hinder with
synchronization cleanup without any real performance benefits.
In try_to_freeze_tasks(), open code self test and move PF_NOFREEZE and
frozen() tests inside freezer_lock in freeze_task().
thaw_processes() can simply drop freezable() test as frozen() test in
__thaw_task() is enough.
Note: This used to be a part of larger patch to fix set_freezable()
race. Separated out to satisfy ordering among dependent fixes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Currently freezing (TIF_FREEZE) and frozen (PF_FROZEN) states are
interlocked - freezing is set to request freeze and when the task
actually freezes, it clears freezing and sets frozen.
This interlocking makes things more complex than necessary - freezing
doesn't mean there's freezing condition in effect and frozen doesn't
match the task actually entering and leaving frozen state (it's
cleared by the thawing task).
This patch makes freezing indicate that freeze condition is in effect.
A task enters and stays frozen if freezing. This makes PF_FROZEN
manipulation done only by the task itself and prevents wakeup from
__thaw_task() leaking outside of refrigerator.
The only place which needs to tell freezing && !frozen is
try_to_freeze_task() to whine about tasks which don't enter frozen.
It's updated to test the condition explicitly.
With the change, frozen() state my linger after __thaw_task() until
the task wakes up and exits fridge. This can trigger BUG_ON() in
update_if_frozen(). Work it around by testing freezing() && frozen()
instead of frozen().
-v2: Oleg pointed out missing re-check of freezing() when trying to
clear FROZEN and possible spurious BUG_ON() trigger in
update_if_frozen(). Both fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Menage <paul@paulmenage.org>
Freezer synchronization is needlessly complicated - it's by no means a
hot path and the priority is staying unintrusive and safe. This patch
makes it simply use a dedicated lock instead of piggy-backing on
task_lock() and playing with memory barriers.
On the failure path of try_to_freeze_tasks(), locking is moved from it
to cancel_freezing(). This makes the frozen() test racy but the race
here is a non-issue as the warning is printed for tasks which failed
to enter frozen for 20 seconds and race on PF_FROZEN at the last
moment doesn't change anything.
This simplifies freezer implementation and eases further changes
including some race fixes.
Signed-off-by: Tejun Heo <tj@kernel.org>
There's no point in thawing nosig tasks before others. There's no
ordering requirement between the two groups on thaw, which the staged
thawing can't guarantee anyway. Simplify thaw_processes() by removing
the distinction and collapsing thaw_tasks() into thaw_processes().
This will help further updates to freezer.
Signed-off-by: Tejun Heo <tj@kernel.org>
