Freezer: make kernel threads nonfreezable by default

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>

35 files changed, 42 insertions, 37 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4503290..06eaa11 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -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) {
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 7c294a4..31be33e 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -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);
diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
index 179c7a3..ec116df 100644
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -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
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index b3ab42e..83c1151 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -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;
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 7b62230..804875d 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -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();
 
diff --git a/drivers/ieee1394/ieee1394_core.c b/drivers/ieee1394/ieee1394_core.c
index 0fc8c6e..ee452595 100644
--- a/drivers/ieee1394/ieee1394_core.c
+++ b/drivers/ieee1394/ieee1394_core.c
@@ -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);
diff --git a/drivers/ieee1394/nodemgr.c b/drivers/ieee1394/nodemgr.c
index 51a1206..2ffd534 100644
--- a/drivers/ieee1394/nodemgr.c
+++ b/drivers/ieee1394/nodemgr.c
@@ -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);
 
diff --git a/drivers/input/gameport/gameport.c b/drivers/input/gameport/gameport.c
index bd686a2..20896d5 100644
--- a/drivers/input/gameport/gameport.c
+++ b/drivers/input/gameport/gameport.c
@@ -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,
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index a8f3bc1..372ca49 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -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,
diff --git a/drivers/input/touchscreen/ucb1400_ts.c b/drivers/input/touchscreen/ucb1400_ts.c
index f0cbcdb..36f9440 100644
--- a/drivers/input/touchscreen/ucb1400_ts.c
+++ b/drivers/input/touchscreen/ucb1400_ts.c
@@ -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;
diff --git a/drivers/macintosh/therm_adt746x.c b/drivers/macintosh/therm_adt746x.c
index bd55e6a..f25685b 100644
--- a/drivers/macintosh/therm_adt746x.c
+++ b/drivers/macintosh/therm_adt746x.c
@@ -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);
diff --git a/drivers/macintosh/windfarm_core.c b/drivers/macintosh/windfarm_core.c
index 4fcb245..e18d265 100644
--- a/drivers/macintosh/windfarm_core.c
+++ b/drivers/macintosh/windfarm_core.c
@@ -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);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 33beaa7..9aefc4a 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -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()) {
 
diff --git a/drivers/media/dvb/dvb-core/dvb_frontend.c b/drivers/media/dvb/dvb-core/dvb_frontend.c
index f4e4ca2..b6c7f66 100644
--- a/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb/dvb-core/dvb_frontend.c
@@ -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:
diff --git a/drivers/media/video/cx88/cx88-tvaudio.c b/drivers/media/video/cx88/cx88-tvaudio.c
index 259ea08..1cc2d28 100644
--- a/drivers/media/video/cx88/cx88-tvaudio.c
+++ b/drivers/media/video/cx88/cx88-tvaudio.c
@@ -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())
diff --git a/drivers/media/video/msp3400-kthreads.c b/drivers/media/video/msp3400-kthreads.c
index e1821eb..d5ee262 100644
--- a/drivers/media/video/msp3400-kthreads.c
+++ b/drivers/media/video/msp3400-kthreads.c
@@ -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);
diff --git a/drivers/media/video/tvaudio.c b/drivers/media/video/tvaudio.c
index c9bf9db..9da338d 100644
--- a/drivers/media/video/tvaudio.c
+++ b/drivers/media/video/tvaudio.c
@@ -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())
diff --git a/drivers/media/video/video-buf-dvb.c b/drivers/media/video/video-buf-dvb.c
index fcc5467..e617925 100644
--- a/drivers/media/video/video-buf-dvb.c
+++ b/drivers/media/video/video-buf-dvb.c
@@ -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 (;;) {
diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
index f7e1d19..3ef4d01 100644
--- a/drivers/media/video/vivi.c
+++ b/drivers/media/video/vivi.c
@@ -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);
diff --git a/drivers/mfd/ucb1x00-ts.c b/drivers/mfd/ucb1x00-ts.c
index 38e815a..fdbaa77 100644
--- a/drivers/mfd/ucb1x00-ts.c
+++ b/drivers/mfd/ucb1x00-ts.c
@@ -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;
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 4fb2089..b53dac8 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -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 {
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 51bc7e2..ef89780 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -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()) {
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 9ecaf77..ab2174a 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -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;
 
diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 1c54908..ee1cc14 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -3086,7 +3086,8 @@ static int airo_thread(void *data) {
 	struct net_device *dev = data;
 	struct airo_info *ai = dev->priv;
 	int locked;
-	
+
+	set_freezable();
 	while(1) {
 		/* make swsusp happy with our thread */
 		try_to_freeze();
diff --git a/drivers/net/wireless/libertas/main.c b/drivers/net/wireless/libertas/main.c
index 4a59306..9f36624 100644
--- a/drivers/net/wireless/libertas/main.c
+++ b/drivers/net/wireless/libertas/main.c
@@ -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",
diff --git a/drivers/pcmcia/cs.c b/drivers/pcmcia/cs.c
index 50cad3a..7c93a10 100644
--- a/drivers/pcmcia/cs.c
+++ b/drivers/pcmcia/cs.c
@@ -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;
diff --git a/drivers/pnp/pnpbios/core.c b/drivers/pnp/pnpbios/core.c
index 3a201b7..03baf1c 100644
--- a/drivers/pnp/pnpbios/core.c
+++ b/drivers/pnp/pnpbios/core.c
@@ -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;
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index d70ddfd..9c5342e 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -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();
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 9adb64a..8a525ab 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -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.
diff --git a/drivers/usb/atm/ueagle-atm.c b/drivers/usb/atm/ueagle-atm.c
index 4973e14..8f04665 100644
--- a/drivers/usb/atm/ueagle-atm.c
+++ b/drivers/usb/atm/ueagle-atm.c
@@ -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)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 50e79010..fd74c50 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2728,6 +2728,7 @@ loop:
 
 static int hub_thread(void *__unused)
 {
+	set_freezable();
 	do {
 		hub_events();
 		wait_event_interruptible(khubd_wait,
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index 8712ef9..be7a1bd 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -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. */
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index bef8bcd..28842d2 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -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 "
diff --git a/drivers/video/ps3fb.c b/drivers/video/ps3fb.c
index 08b7ffb..3972aa8 100644
--- a/drivers/video/ps3fb.c
+++ b/drivers/video/ps3fb.c
@@ -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);
diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index f5c5b76..c633210 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -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;