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Freezer: make kernel threads nonfreezable by default

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Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rafael J. Wysocki 2007-07-17 04:03:35 -07:00 committed by Linus Torvalds
parent 787d2214c1
commit 8314418629
65 changed files with 256 additions and 113 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

160
Documentation/power/freezing-of-tasks.txt Normal file
View file

@ -0,0 +1,160 @@
Freezing of tasks
(C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL
I. What is the freezing of tasks?
The freezing of tasks is a mechanism by which user space processes and some
kernel threads are controlled during hibernation or system-wide suspend (on some
architectures).
II. How does it work?
There are four per-task flags used for that, PF_NOFREEZE, PF_FROZEN, TIF_FREEZE
and PF_FREEZER_SKIP (the last one is auxiliary). The tasks that have
PF_NOFREEZE unset (all user space processes and some kernel threads) are
regarded as 'freezable' and treated in a special way before the system enters a
suspend state as well as before a hibernation image is created (in what follows
we only consider hibernation, but the description also applies to suspend).
Namely, as the first step of the hibernation procedure the function
freeze_processes() (defined in kernel/power/process.c) is called. It executes
try_to_freeze_tasks() that sets TIF_FREEZE for all of the freezable tasks and
sends a fake signal to each of them. A task that receives such a signal and has
TIF_FREEZE set, should react to it by calling the refrigerator() function
(defined in kernel/power/process.c), which sets the task's PF_FROZEN flag,
changes its state to TASK_UNINTERRUPTIBLE and makes it loop until PF_FROZEN is
cleared for it. Then, we say that the task is 'frozen' and therefore the set of
functions handling this mechanism is called 'the freezer' (these functions are
defined in kernel/power/process.c and include/linux/freezer.h). User space
processes are generally frozen before kernel threads.
It is not recommended to call refrigerator() directly. Instead, it is
recommended to use the try_to_freeze() function (defined in
include/linux/freezer.h), that checks the task's TIF_FREEZE flag and makes the
task enter refrigerator() if the flag is set.
For user space processes try_to_freeze() is called automatically from the
signal-handling code, but the freezable kernel threads need to call it
explicitly in suitable places. The code to do this may look like the following:
do {
hub_events();
wait_event_interruptible(khubd_wait,
!list_empty(&hub_event_list));
try_to_freeze();
} while (!signal_pending(current));
(from drivers/usb/core/hub.c::hub_thread()).
If a freezable kernel thread fails to call try_to_freeze() after the freezer has
set TIF_FREEZE for it, the freezing of tasks will fail and the entire
hibernation operation will be cancelled. For this reason, freezable kernel
threads must call try_to_freeze() somewhere.
After the system memory state has been restored from a hibernation image and
devices have been reinitialized, the function thaw_processes() is called in
order to clear the PF_FROZEN flag for each frozen task. Then, the tasks that
have been frozen leave refrigerator() and continue running.
III. Which kernel threads are freezable?
Kernel threads are not freezable by default. However, a kernel thread may clear
PF_NOFREEZE for itself by calling set_freezable() (the resetting of PF_NOFREEZE
directly is strongly discouraged). From this point it is regarded as freezable
and must call try_to_freeze() in a suitable place.
IV. Why do we do that?
Generally speaking, there is a couple of reasons to use the freezing of tasks:
1. The principal reason is to prevent filesystems from being damaged after
hibernation. At the moment we have no simple means of checkpointing
filesystems, so if there are any modifications made to filesystem data and/or
metadata on disks, we cannot bring them back to the state from before the
modifications. At the same time each hibernation image contains some
filesystem-related information that must be consistent with the state of the
on-disk data and metadata after the system memory state has been restored from
the image (otherwise the filesystems will be damaged in a nasty way, usually
making them almost impossible to repair). We therefore freeze tasks that might
cause the on-disk filesystems' data and metadata to be modified after the
hibernation image has been created and before the system is finally powered off.
The majority of these are user space processes, but if any of the kernel threads
may cause something like this to happen, they have to be freezable.
2. The second reason is to prevent user space processes and some kernel threads
from interfering with the suspending and resuming of devices. A user space
process running on a second CPU while we are suspending devices may, for
example, be troublesome and without the freezing of tasks we would need some
safeguards against race conditions that might occur in such a case.
Although Linus Torvalds doesn't like the freezing of tasks, he said this in one
of the discussions on LKML (http://lkml.org/lkml/2007/4/27/608):
"RJW:> Why we freeze tasks at all or why we freeze kernel threads?
Linus: In many ways, 'at all'.
I _do_ realize the IO request queue issues, and that we cannot actually do
s2ram with some devices in the middle of a DMA. So we want to be able to
avoid *that*, there's no question about that. And I suspect that stopping
user threads and then waiting for a sync is practically one of the easier
ways to do so.
So in practice, the 'at all' may become a 'why freeze kernel threads?' and
freezing user threads I don't find really objectionable."
Still, there are kernel threads that may want to be freezable. For example, if
a kernel that belongs to a device driver accesses the device directly, it in
principle needs to know when the device is suspended, so that it doesn't try to
access it at that time. However, if the kernel thread is freezable, it will be
frozen before the driver's .suspend() callback is executed and it will be
thawed after the driver's .resume() callback has run, so it won't be accessing
the device while it's suspended.
3. Another reason for freezing tasks is to prevent user space processes from
realizing that hibernation (or suspend) operation takes place. Ideally, user
space processes should not notice that such a system-wide operation has occurred
and should continue running without any problems after the restore (or resume
from suspend). Unfortunately, in the most general case this is quite difficult
to achieve without the freezing of tasks. Consider, for example, a process
that depends on all CPUs being online while it's running. Since we need to
disable nonboot CPUs during the hibernation, if this process is not frozen, it
may notice that the number of CPUs has changed and may start to work incorrectly
because of that.
V. Are there any problems related to the freezing of tasks?
Yes, there are.
First of all, the freezing of kernel threads may be tricky if they depend one
on another. For example, if kernel thread A waits for a completion (in the
TASK_UNINTERRUPTIBLE state) that needs to be done by freezable kernel thread B
and B is frozen in the meantime, then A will be blocked until B is thawed, which
may be undesirable. That's why kernel threads are not freezable by default.
Second, there are the following two problems related to the freezing of user
space processes:
1. Putting processes into an uninterruptible sleep distorts the load average.
2. Now that we have FUSE, plus the framework for doing device drivers in
userspace, it gets even more complicated because some userspace processes are
now doing the sorts of things that kernel threads do
(https://lists.linux-foundation.org/pipermail/linux-pm/2007-May/012309.html).
The problem 1. seems to be fixable, although it hasn't been fixed so far. The
other one is more serious, but it seems that we can work around it by using
hibernation (and suspend) notifiers (in that case, though, we won't be able to
avoid the realization by the user space processes that the hibernation is taking
place).
There are also problems that the freezing of tasks tends to expose, although
they are not directly related to it. For example, if request_firmware() is
called from a device driver's .resume() routine, it will timeout and eventually
fail, because the user land process that should respond to the request is frozen
at this point. So, seemingly, the failure is due to the freezing of tasks.
Suppose, however, that the firmware file is located on a filesystem accessible
only through another device that hasn't been resumed yet. In that case,
request_firmware() will fail regardless of whether or not the freezing of tasks
is used. Consequently, the problem is not really related to the freezing of
tasks, since it generally exists anyway. [The solution to this particular
problem is to keep the firmware in memory after it's loaded for the first time
and upload if from memory to the device whenever necessary.]

40
Documentation/power/kernel_threads.txt
View file

@ -1,40 +0,0 @@
KERNEL THREADS
Freezer
Upon entering a suspended state the system will freeze all
tasks. This is done by delivering pseudosignals. This affects
kernel threads, too. To successfully freeze a kernel thread
the thread has to check for the pseudosignal and enter the
refrigerator. Code to do this looks like this:
do {
hub_events();
wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
try_to_freeze();
} while (!signal_pending(current));
from drivers/usb/core/hub.c::hub_thread()
The Unfreezable
Some kernel threads however, must not be frozen. The kernel must
be able to finish pending IO operations and later on be able to
write the memory image to disk. Kernel threads needed to do IO
must stay awake. Such threads must mark themselves unfreezable
like this:
/*
* This thread doesn't need any user-level access,
* so get rid of all our resources.
*/
daemonize("usb-storage");
current->flags |= PF_NOFREEZE;
from drivers/usb/storage/usb.c::usb_stor_control_thread()
Such drivers are themselves responsible for staying quiet during
the actual snapshotting.

18
Documentation/power/swsusp.txt
View file

@ -140,21 +140,11 @@ should be sent to the mailing list available through the suspend2
website, and not to the Linux Kernel Mailing List. We are working
toward merging suspend2 into the mainline kernel.
Q: A kernel thread must voluntarily freeze itself (call 'refrigerator').
I found some kernel threads that don't do it, and they don't freeze
so the system can't sleep. Is this a known behavior?
A: All such kernel threads need to be fixed, one by one. Select the
place where the thread is safe to be frozen (no kernel semaphores
should be held at that point and it must be safe to sleep there), and
add:
try_to_freeze();
If the thread is needed for writing the image to storage, you should
instead set the PF_NOFREEZE process flag when creating the thread (and
be very careful).
Q: What is the freezing of tasks and why are we using it?
A: The freezing of tasks is a mechanism by which user space processes and some
kernel threads are controlled during hibernation or system-wide suspend (on some
architectures). See freezing-of-tasks.txt for details.
Q: What is the difference between "platform" and "shutdown"?

2
arch/i386/kernel/apm.c
View file

@ -222,6 +222,7 @@
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/freezer.h>
#include <linux/smp.h>
#include <linux/dmi.h>
#include <linux/suspend.h>
@ -2311,7 +2312,6 @@ static int __init apm_init(void)
remove_proc_entry("apm", NULL);
return err;
}
kapmd_task->flags |= PF_NOFREEZE;
wake_up_process(kapmd_task);
if (num_online_cpus() > 1 && !smp ) {

1
arch/i386/kernel/io_apic.c
View file

@ -667,6 +667,7 @@ static int balanced_irq(void *unused)
set_pending_irq(i, cpumask_of_cpu(0));
}
set_freezable();
for ( ; ; ) {
time_remaining = schedule_timeout_interruptible(time_remaining);
try_to_freeze();

8
drivers/block/loop.c
View file

@ -68,6 +68,7 @@
#include <linux/loop.h>
#include <linux/compat.h>
#include <linux/suspend.h>
#include <linux/freezer.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h> /* for invalidate_bdev() */
#include <linux/completion.h>
@ -600,13 +601,6 @@ static int loop_thread(void *data)
struct loop_device *lo = data;
struct bio *bio;
/*
* loop can be used in an encrypted device,
* hence, it mustn't be stopped at all
* because it could be indirectly used during suspension
*/
current->flags |= PF_NOFREEZE;
set_user_nice(current, -20);
while (!kthread_should_stop() || lo->lo_bio) {

1
drivers/block/pktcdvd.c
View file

@ -1593,6 +1593,7 @@ static int kcdrwd(void *foobar)
long min_sleep_time, residue;
set_user_nice(current, -20);
set_freezable();
for (;;) {
DECLARE_WAITQUEUE(wait, current);

12
drivers/char/apm-emulation.c
View file

@ -20,6 +20,7 @@
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/apm-emulation.h>
#include <linux/freezer.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/list.h>
@ -329,13 +330,8 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
/*
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
*
* Note: we need to ensure that the PM subsystem does
* not kick us out of the wait when it suspends the
* threads.
*/
flags = current->flags;
current->flags |= PF_NOFREEZE;
wait_event(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
@ -365,13 +361,8 @@ apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
/*
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
*
* Note: we need to ensure that the PM subsystem does
* not kick us out of the wait when it suspends the
* threads.
*/
flags = current->flags;
current->flags |= PF_NOFREEZE;
wait_event_interruptible(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
@ -598,7 +589,6 @@ static int __init apm_init(void)
kapmd_tsk = NULL;
return ret;
}
kapmd_tsk->flags |= PF_NOFREEZE;
wake_up_process(kapmd_tsk);
#ifdef CONFIG_PROC_FS

1
drivers/char/hvc_console.c
View file

@ -679,6 +679,7 @@ static int khvcd(void *unused)
int poll_mask;
struct hvc_struct *hp;
set_freezable();
__set_current_state(TASK_RUNNING);
do {
poll_mask = 0;

1
drivers/edac/edac_mc.c
View file

@ -1906,6 +1906,7 @@ static void do_edac_check(void)
static int edac_kernel_thread(void *arg)
{
set_freezable();
while (!kthread_should_stop()) {
do_edac_check();

3
drivers/ieee1394/ieee1394_core.c
View file

@ -30,6 +30,7 @@
#include <linux/moduleparam.h>
#include <linux/bitops.h>
#include <linux/kdev_t.h>
#include <linux/freezer.h>
#include <linux/suspend.h>
#include <linux/kthread.h>
#include <linux/preempt.h>
@ -1128,8 +1129,6 @@ static int hpsbpkt_thread(void *__hi)
struct list_head tmp;
int may_schedule;
current->flags |= PF_NOFREEZE;
while (!kthread_should_stop()) {
INIT_LIST_HEAD(&tmp);

1
drivers/ieee1394/nodemgr.c
View file

@ -1699,6 +1699,7 @@ static int nodemgr_host_thread(void *__hi)
unsigned int g, generation = 0;
int i, reset_cycles = 0;
set_freezable();
/* Setup our device-model entries */
nodemgr_create_host_dev_files(host);

1
drivers/input/gameport/gameport.c
View file

@ -445,6 +445,7 @@ static struct gameport *gameport_get_pending_child(struct gameport *parent)
static int gameport_thread(void *nothing)
{
set_freezable();
do {
gameport_handle_event();
wait_event_interruptible(gameport_wait,

1
drivers/input/serio/serio.c
View file

@ -384,6 +384,7 @@ static struct serio *serio_get_pending_child(struct serio *parent)
static int serio_thread(void *nothing)
{
set_freezable();
do {
serio_handle_event();
wait_event_interruptible(serio_wait,

1
drivers/input/touchscreen/ucb1400_ts.c
View file

@ -292,6 +292,7 @@ static int ucb1400_ts_thread(void *_ucb)
sched_setscheduler(tsk, SCHED_FIFO, &param);
set_freezable();
while (!kthread_should_stop()) {
unsigned int x, y, p;
long timeout;

1
drivers/macintosh/therm_adt746x.c
View file

@ -335,6 +335,7 @@ static int monitor_task(void *arg)
{
struct thermostat* th = arg;
set_freezable();
while(!kthread_should_stop()) {
try_to_freeze();
msleep_interruptible(2000);

1
drivers/macintosh/windfarm_core.c
View file

@ -92,6 +92,7 @@ static int wf_thread_func(void *data)
DBG("wf: thread started\n");
set_freezable();
while(!kthread_should_stop()) {
if (time_after_eq(jiffies, next)) {
wf_notify(WF_EVENT_TICK, NULL);

1
drivers/md/md.c
View file

@ -4642,7 +4642,6 @@ static int md_thread(void * arg)
* many dirty RAID5 blocks.
*/
current->flags |= PF_NOFREEZE;
allow_signal(SIGKILL);
while (!kthread_should_stop()) {

1
drivers/media/dvb/dvb-core/dvb_frontend.c
View file

@ -523,6 +523,7 @@ static int dvb_frontend_thread(void *data)
dvb_frontend_init(fe);
set_freezable();
while (1) {
up(&fepriv->sem); /* is locked when we enter the thread... */
restart:

1
drivers/media/video/cx88/cx88-tvaudio.c
View file

@ -906,6 +906,7 @@ int cx88_audio_thread(void *data)
u32 mode = 0;
dprintk("cx88: tvaudio thread started\n");
set_freezable();
for (;;) {
msleep_interruptible(1000);
if (kthread_should_stop())

6
drivers/media/video/msp3400-kthreads.c
View file

@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/freezer.h>
#include <linux/videodev.h>
#include <linux/videodev2.h>
#include <media/v4l2-common.h>
@ -468,6 +469,7 @@ int msp3400c_thread(void *data)
v4l_dbg(1, msp_debug, client, "msp3400 daemon started\n");
set_freezable();
for (;;) {
v4l_dbg(2, msp_debug, client, "msp3400 thread: sleep\n");
msp_sleep(state, -1);
@ -646,7 +648,7 @@ int msp3410d_thread(void *data)
int val, i, std, count;
v4l_dbg(1, msp_debug, client, "msp3410 daemon started\n");
set_freezable();
for (;;) {
v4l_dbg(2, msp_debug, client, "msp3410 thread: sleep\n");
msp_sleep(state,-1);
@ -940,7 +942,7 @@ int msp34xxg_thread(void *data)
int val, i;
v4l_dbg(1, msp_debug, client, "msp34xxg daemon started\n");
set_freezable();
for (;;) {
v4l_dbg(2, msp_debug, client, "msp34xxg thread: sleep\n");
msp_sleep(state, -1);

2
drivers/media/video/tvaudio.c
View file

@ -271,7 +271,7 @@ static int chip_thread(void *data)
struct CHIPDESC *desc = chiplist + chip->type;
v4l_dbg(1, debug, &chip->c, "%s: thread started\n", chip->c.name);
set_freezable();
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
if (!kthread_should_stop())

1
drivers/media/video/video-buf-dvb.c
View file

@ -47,6 +47,7 @@ static int videobuf_dvb_thread(void *data)
int err;
dprintk("dvb thread started\n");
set_freezable();
videobuf_read_start(&dvb->dvbq);
for (;;) {

1
drivers/media/video/vivi.c
View file

@ -573,6 +573,7 @@ static int vivi_thread(void *data)
dprintk(1,"thread started\n");
mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
set_freezable();
for (;;) {
vivi_sleep(dma_q);

1
drivers/mfd/ucb1x00-ts.c
View file

@ -209,6 +209,7 @@ static int ucb1x00_thread(void *_ts)
DECLARE_WAITQUEUE(wait, tsk);
int valid = 0;
set_freezable();
add_wait_queue(&ts->irq_wait, &wait);
while (!kthread_should_stop()) {
unsigned int x, y, p;

7
drivers/mmc/card/queue.c
View file

@ -11,6 +11,7 @@
*/
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/mmc/card.h>
@ -44,11 +45,7 @@ static int mmc_queue_thread(void *d)
struct mmc_queue *mq = d;
struct request_queue *q = mq->queue;
/*
* Set iothread to ensure that we aren't put to sleep by
* the process freezing. We handle suspension ourselves.
*/
current->flags |= PF_MEMALLOC|PF_NOFREEZE;
current->flags |= PF_MEMALLOC;
down(&mq->thread_sem);
do {

3
drivers/mtd/mtd_blkdevs.c
View file

@ -16,6 +16,7 @@
#include <linux/mtd/mtd.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/freezer.h>
#include <linux/spinlock.h>
#include <linux/hdreg.h>
#include <linux/init.h>
@ -80,7 +81,7 @@ static int mtd_blktrans_thread(void *arg)
struct request_queue *rq = tr->blkcore_priv->rq;
/* we might get involved when memory gets low, so use PF_MEMALLOC */
current->flags |= PF_MEMALLOC | PF_NOFREEZE;
current->flags |= PF_MEMALLOC;
spin_lock_irq(rq->queue_lock);
while (!kthread_should_stop()) {

1
drivers/mtd/ubi/wl.c
View file

@ -1346,6 +1346,7 @@ static int ubi_thread(void *u)
ubi_msg("background thread \"%s\" started, PID %d",
ubi->bgt_name, current->pid);
set_freezable();
for (;;) {
int err;

1
drivers/net/wireless/airo.c
View file

@ -3087,6 +3087,7 @@ static int airo_thread(void *data) {
struct airo_info *ai = dev->priv;
int locked;
set_freezable();
while(1) {
/* make swsusp happy with our thread */
try_to_freeze();

1
drivers/net/wireless/libertas/main.c
View file

@ -613,6 +613,7 @@ static int wlan_service_main_thread(void *data)
init_waitqueue_entry(&wait, current);
set_freezable();
for (;;) {
lbs_deb_thread( "main-thread 111: intcounter=%d "
"currenttxskb=%p dnld_sent=%d\n",

1
drivers/pcmcia/cs.c
View file

@ -651,6 +651,7 @@ static int pccardd(void *__skt)
add_wait_queue(&skt->thread_wait, &wait);
complete(&skt->thread_done);
set_freezable();
for (;;) {
unsigned long flags;
unsigned int events;

1
drivers/pnp/pnpbios/core.c
View file

@ -160,6 +160,7 @@ static int pnp_dock_thread(void * unused)
{
static struct pnp_docking_station_info now;
int docked = -1, d = 0;
set_freezable();
while (!unloading)
{
int status;

3
drivers/scsi/libsas/sas_scsi_host.c
View file

@ -40,6 +40,7 @@
#include <linux/err.h>
#include <linux/blkdev.h>
#include <linux/freezer.h>
#include <linux/scatterlist.h>
/* ---------- SCSI Host glue ---------- */
@ -868,8 +869,6 @@ static int sas_queue_thread(void *_sas_ha)
{
struct sas_ha_struct *sas_ha = _sas_ha;
current->flags |= PF_NOFREEZE;
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();

3
drivers/scsi/scsi_error.c
View file

@ -19,6 +19,7 @@
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/interrupt.h>
#include <linux/blkdev.h>
@ -1516,8 +1517,6 @@ int scsi_error_handler(void *data)
{
struct Scsi_Host *shost = data;
current->flags |= PF_NOFREEZE;
/*
* We use TASK_INTERRUPTIBLE so that the thread is not
* counted against the load average as a running process.

1
drivers/usb/atm/ueagle-atm.c
View file

@ -1168,6 +1168,7 @@ static int uea_kthread(void *data)
struct uea_softc *sc = data;
int ret = -EAGAIN;
set_freezable();
uea_enters(INS_TO_USBDEV(sc));
while (!kthread_should_stop()) {
if (ret < 0 || sc->reset)

1
drivers/usb/core/hub.c
View file

@ -2728,6 +2728,7 @@ static void hub_events(void)
static int hub_thread(void *__unused)
{
set_freezable();
do {
hub_events();
wait_event_interruptible(khubd_wait,

3
drivers/usb/gadget/file_storage.c
View file

@ -3434,6 +3434,9 @@ static int fsg_main_thread(void *fsg_)
allow_signal(SIGKILL);
allow_signal(SIGUSR1);
/* Allow the thread to be frozen */
set_freezable();
/* Arrange for userspace references to be interpreted as kernel
* pointers. That way we can pass a kernel pointer to a routine
* that expects a __user pointer and it will work okay. */

3
drivers/usb/storage/usb.c
View file

@ -311,8 +311,6 @@ static int usb_stor_control_thread(void * __us)
struct Scsi_Host *host = us_to_host(us);
int autopm_rc;
current->flags |= PF_NOFREEZE;
for(;;) {
US_DEBUGP("*** thread sleeping.\n");
if(down_interruptible(&us->sema))
@ -920,6 +918,7 @@ static int usb_stor_scan_thread(void * __us)
printk(KERN_DEBUG
"usb-storage: device found at %d\n", us->pusb_dev->devnum);
set_freezable();
/* Wait for the timeout to expire or for a disconnect */
if (delay_use > 0) {
printk(KERN_DEBUG "usb-storage: waiting for device "

1
drivers/video/ps3fb.c
View file

@ -812,6 +812,7 @@ static int ps3fb_ioctl(struct fb_info *info, unsigned int cmd,
static int ps3fbd(void *arg)
{
set_freezable();
while (!kthread_should_stop()) {
try_to_freeze();
set_current_state(TASK_INTERRUPTIBLE);

1
drivers/w1/w1.c
View file

@ -805,6 +805,7 @@ static int w1_control(void *data)
struct w1_master *dev, *n;
int have_to_wait = 0;
set_freezable();
while (!kthread_should_stop() || have_to_wait) {
have_to_wait = 0;

1
fs/cifs/cifsfs.c
View file

@ -849,6 +849,7 @@ static int cifs_oplock_thread(void * dummyarg)
__u16 netfid;
int rc;
set_freezable();
do {
if (try_to_freeze())
continue;

1
fs/cifs/connect.c
View file

@ -363,6 +363,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
GFP_KERNEL);
}
set_freezable();
while (!kthread_should_stop()) {
if (try_to_freeze())
continue;

1
fs/jffs2/background.c
View file

@ -81,6 +81,7 @@ static int jffs2_garbage_collect_thread(void *_c)
set_user_nice(current, 10);
set_freezable();
for (;;) {
allow_signal(SIGHUP);

2
fs/lockd/svc.c
View file

@ -25,6 +25,7 @@
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/stats.h>
@ -119,6 +120,7 @@ lockd(struct svc_rqst *rqstp)
complete(&lockd_start_done);
daemonize("lockd");
set_freezable();
/* Process request with signals blocked, but allow SIGKILL. */
allow_signal(SIGKILL);

2
fs/nfs/callback.c
View file

@ -14,6 +14,7 @@
#include <linux/sunrpc/svcsock.h>
#include <linux/nfs_fs.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <net/inet_sock.h>
@ -67,6 +68,7 @@ static void nfs_callback_svc(struct svc_rqst *rqstp)
daemonize("nfsv4-svc");
/* Process request with signals blocked, but allow SIGKILL. */
allow_signal(SIGKILL);
set_freezable();
complete(&nfs_callback_info.started);

2
fs/nfsd/nfssvc.c
View file

@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/freezer.h>
#include <linux/fs_struct.h>
#include <linux/sunrpc/types.h>
@ -432,6 +433,7 @@ nfsd(struct svc_rqst *rqstp)
* dirty pages.
*/
current->flags |= PF_LESS_THROTTLE;
set_freezable();
/*
* The main request loop

1
fs/xfs/linux-2.6/xfs_super.c
View file

@ -562,6 +562,7 @@ xfssyncd(
bhv_vfs_sync_work_t *work, *n;
LIST_HEAD (tmp);
set_freezable();
timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
for (;;) {
timeleft = schedule_timeout_interruptible(timeleft);

14
include/linux/freezer.h
View file

@ -1,5 +1,8 @@
/* Freezer declarations */
#ifndef FREEZER_H_INCLUDED
#define FREEZER_H_INCLUDED
#include <linux/sched.h>
#ifdef CONFIG_PM
@ -115,6 +118,14 @@ static inline int freezer_should_skip(struct task_struct *p)
return !!(p->flags & PF_FREEZER_SKIP);
}
/*
* Tell the freezer that the current task should be frozen by it
*/
static inline void set_freezable(void)
{
current->flags &= ~PF_NOFREEZE;
}
#else
static inline int frozen(struct task_struct *p) { return 0; }
static inline int freezing(struct task_struct *p) { return 0; }
@ -130,4 +141,7 @@ static inline int try_to_freeze(void) { return 0; }
static inline void freezer_do_not_count(void) {}
static inline void freezer_count(void) {}
static inline int freezer_should_skip(struct task_struct *p) { return 0; }
static inline void set_freezable(void) {}
#endif
#endif /* FREEZER_H_INCLUDED */

7
init/do_mounts_initrd.c
View file

@ -56,12 +56,9 @@ static void __init handle_initrd(void)
sys_chroot(".");
pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
if (pid > 0) {
while (pid != sys_wait4(-1, NULL, 0, NULL)) {
try_to_freeze();
if (pid > 0)
while (pid != sys_wait4(-1, NULL, 0, NULL))
yield();
}
}
/* move initrd to rootfs' /old */
sys_fchdir(old_fd);

1
kernel/audit.c
View file

@ -392,6 +392,7 @@ static int kauditd_thread(void *dummy)
{
struct sk_buff *skb;
set_freezable();
while (!kthread_should_stop()) {
skb = skb_dequeue(&audit_skb_queue);
wake_up(&audit_backlog_wait);

6
kernel/exit.c
View file

@ -31,6 +31,7 @@
#include <linux/mempolicy.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
#include <linux/freezer.h>
#include <linux/cpuset.h>
#include <linux/syscalls.h>
#include <linux/signal.h>
@ -387,6 +388,11 @@ void daemonize(const char *name, ...)
* they would be locked into memory.
*/
exit_mm(current);
/*
* We don't want to have TIF_FREEZE set if the system-wide hibernation
* or suspend transition begins right now.
*/
current->flags |= PF_NOFREEZE;
set_special_pids(1, 1);
proc_clear_tty(current);

2
kernel/fork.c
View file

@ -923,7 +923,7 @@ static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
{
unsigned long new_flags = p->flags;
new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
new_flags &= ~PF_SUPERPRIV;
new_flags |= PF_FORKNOEXEC;
if (!(clone_flags & CLONE_PTRACE))
p->ptrace = 0;

4
kernel/rcutorture.c
View file

@ -40,6 +40,7 @@
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/random.h>
#include <linux/delay.h>
@ -518,7 +519,6 @@ rcu_torture_writer(void *arg)
VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
set_user_nice(current, 19);
current->flags |= PF_NOFREEZE;
do {
schedule_timeout_uninterruptible(1);
@ -558,7 +558,6 @@ rcu_torture_fakewriter(void *arg)
VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
set_user_nice(current, 19);
current->flags |= PF_NOFREEZE;
do {
schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
@ -589,7 +588,6 @@ rcu_torture_reader(void *arg)
VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
set_user_nice(current, 19);
current->flags |= PF_NOFREEZE;
do {
idx = cur_ops->readlock();

1
kernel/rtmutex-tester.c
View file

@ -260,6 +260,7 @@ static int test_func(void *data)
int ret;
current->flags |= PF_MUTEX_TESTER;
set_freezable();
allow_signal(SIGHUP);
for(;;) {

3
kernel/sched.c
View file

@ -4912,8 +4912,6 @@ static int migration_thread(void *data)
struct migration_req *req;
struct list_head *head;
try_to_freeze();
spin_lock_irq(&rq->lock);
if (cpu_is_offline(cpu)) {
@ -5147,7 +5145,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
p = kthread_create(migration_thread, hcpu, "migration/%d", cpu);
if (IS_ERR(p))
return NOTIFY_BAD;
p->flags |= PF_NOFREEZE;
kthread_bind(p, cpu);
/* Must be high prio: stop_machine expects to yield to it. */
rq = task_rq_lock(p, &flags);

3
kernel/softirq.c
View file

@ -14,6 +14,7 @@
#include <linux/notifier.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/rcupdate.h>
#include <linux/smp.h>
@ -488,8 +489,6 @@ void __init softirq_init(void)
static int ksoftirqd(void * __bind_cpu)
{
current->flags |= PF_NOFREEZE;
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {

2
kernel/softlockup.c
View file

@ -10,6 +10,7 @@
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/notifier.h>
#include <linux/module.h>
@ -116,7 +117,6 @@ static int watchdog(void * __bind_cpu)
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
sched_setscheduler(current, SCHED_FIFO, &param);
current->flags |= PF_NOFREEZE;
/* initialize timestamp */
touch_softlockup_watchdog();

4
kernel/workqueue.c
View file

@ -282,8 +282,8 @@ static int worker_thread(void *__cwq)
struct cpu_workqueue_struct *cwq = __cwq;
DEFINE_WAIT(wait);
if (!cwq->wq->freezeable)
current->flags |= PF_NOFREEZE;
if (cwq->wq->freezeable)
set_freezable();
set_user_nice(current, -5);

1
mm/pdflush.c
View file

@ -92,6 +92,7 @@ struct pdflush_work {
static int __pdflush(struct pdflush_work *my_work)
{
current->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
my_work->fn = NULL;
my_work->who = current;
INIT_LIST_HEAD(&my_work->list);

1
mm/vmscan.c
View file

@ -1421,6 +1421,7 @@ static int kswapd(void *p)
* trying to free the first piece of memory in the first place).
*/
tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
set_freezable();
order = 0;
for ( ; ; ) {

2
net/bluetooth/bnep/core.c
View file

@ -36,6 +36,7 @@
#include <linux/signal.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/freezer.h>
#include <linux/errno.h>
#include <linux/net.h>
#include <net/sock.h>
@ -474,7 +475,6 @@ static int bnep_session(void *arg)
daemonize("kbnepd %s", dev->name);
set_user_nice(current, -15);
current->flags |= PF_NOFREEZE;
init_waitqueue_entry(&wait, current);
add_wait_queue(sk->sk_sleep, &wait);

2
net/bluetooth/cmtp/core.c
View file

@ -29,6 +29,7 @@
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/fcntl.h>
#include <linux/freezer.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/ioctl.h>
@ -287,7 +288,6 @@ static int cmtp_session(void *arg)
daemonize("kcmtpd_ctr_%d", session->num);
set_user_nice(current, -15);
current->flags |= PF_NOFREEZE;
init_waitqueue_entry(&wait, current);
add_wait_queue(sk->sk_sleep, &wait);

2
net/bluetooth/hidp/core.c
View file

@ -28,6 +28,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/freezer.h>
#include <linux/fcntl.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
@ -547,7 +548,6 @@ static int hidp_session(void *arg)
daemonize("khidpd_%04x%04x", vendor, product);
set_user_nice(current, -15);
current->flags |= PF_NOFREEZE;
init_waitqueue_entry(&ctrl_wait, current);
init_waitqueue_entry(&intr_wait, current);

2
net/bluetooth/rfcomm/core.c
View file

@ -33,6 +33,7 @@
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/init.h>
#include <linux/freezer.h>
#include <linux/wait.h>
#include <linux/device.h>
#include <linux/net.h>
@ -1940,7 +1941,6 @@ static int rfcomm_run(void *unused)
daemonize("krfcommd");
set_user_nice(current, -10);
current->flags |= PF_NOFREEZE;
BT_DBG("");

2
net/core/pktgen.c
View file

@ -3465,6 +3465,8 @@ static int pktgen_thread_worker(void *arg)
set_current_state(TASK_INTERRUPTIBLE);
set_freezable();
while (!kthread_should_stop()) {
pkt_dev = next_to_run(t);