Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes

[Christoph Lameter <christoph@lameter.com>]

On Sat, 25 Jun 2005, Pavel Machek wrote:

> It includes whitespace changes and most of patch is nice cleanup that
> should probably go in separately. (Hint hint :-). 

> Previous code had important property: try_to_freeze was optimized away
> in !CONFIG_PM case. Please keep that.
> 
> Best way is to introduce macros and cleanup the code to use the
> macros, without actually changing any object code. That can go in very
> fast. Then we can switch to atomic_t ... yeah I think that's
> neccessary, but I'd like cleanups first.

Here is such a patch:

---
Cleanup patch for freezing against 2.6.12-git5.

1. Establish a simple API for process freezing defined in linux/include/sched.h:

frozen(process)		Check for frozen process
freezing(process)	Check if a process is being frozen
freeze(process)		Tell a process to freeze (go to refrigerator)
thaw_process(process)	Restart process
frozen_process(process)		Process is frozen now

2. Remove all references to PF_FREEZE and PF_FROZEN from all
   kernel sources except sched.h

3. Fix numerous locations where try_to_freeze is manually done by a driver

4. Remove the argument that is no longer necessary from two function calls.

5. Some whitespace cleanup

6. Clear potential race in refrigerator (provides an open window of PF_FREEZE
   cleared before setting PF_FROZEN, recalc_sigpending does not check 
   PF_FROZEN).

This patch does not address the problem of freeze_processes() violating the rule
that a task may only modify its own flags by setting PF_FREEZE. This is not clean
in an SMP environment. freeze(process) is therefore not SMP safe!

Signed-off-by: Christoph Lameter <christoph@lameter.com>

Index: linux-2.6.12/drivers/block/pktcdvd.c
===================================================================
--- linux-2.6.12.orig/drivers/block/pktcdvd.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/block/pktcdvd.c	2005-06-25 05:01:28.000000000 +0000
@@ -1251,8 +1251,7 @@ static int kcdrwd(void *foobar)
 			VPRINTK("kcdrwd: wake up\n");
 
 			/* make swsusp happy with our thread */
-			if (current->flags & PF_FREEZE)
-				refrigerator(PF_FREEZE);
+			try_to_freeze();
 
 			list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
 				if (!pkt->sleep_time)
Index: linux-2.6.12/kernel/power/process.c
===================================================================
--- linux-2.6.12.orig/kernel/power/process.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/kernel/power/process.c	2005-06-25 05:33:16.000000000 +0000
@@ -32,7 +32,7 @@ static inline int freezeable(struct task
 }
 
 /* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(unsigned long flag)
+void refrigerator(void)
 {
 	/* Hmm, should we be allowed to suspend when there are realtime
 	   processes around? */
@@ -41,14 +41,13 @@ void refrigerator(unsigned long flag)
 	current->state = TASK_UNINTERRUPTIBLE;
 	pr_debug("%s entered refrigerator\n", current->comm);
 	printk("=");
-	current->flags &= ~PF_FREEZE;
 
+	frozen_process(current);
 	spin_lock_irq(&current->sighand->siglock);
 	recalc_sigpending(); /* We sent fake signal, clean it up */
 	spin_unlock_irq(&current->sighand->siglock);
 
-	current->flags |= PF_FROZEN;
-	while (current->flags & PF_FROZEN)
+	while (frozen(current))
 		schedule();
 	pr_debug("%s left refrigerator\n", current->comm);
 	current->state = save;
@@ -57,10 +56,10 @@ void refrigerator(unsigned long flag)
 /* 0 = success, else # of processes that we failed to stop */
 int freeze_processes(void)
 {
-       int todo;
-       unsigned long start_time;
+	int todo;
+	unsigned long start_time;
 	struct task_struct *g, *p;
-	
+
 	printk( "Stopping tasks: " );
 	start_time = jiffies;
 	do {
@@ -70,14 +69,12 @@ int freeze_processes(void)
 			unsigned long flags;
 			if (!freezeable(p))
 				continue;
-			if ((p->flags & PF_FROZEN) ||
+			if ((frozen(p)) ||
 			    (p->state == TASK_TRACED) ||
 			    (p->state == TASK_STOPPED))
 				continue;
 
-			/* FIXME: smp problem here: we may not access other process' flags
-			   without locking */
-			p->flags |= PF_FREEZE;
+			freeze(p);
 			spin_lock_irqsave(&p->sighand->siglock, flags);
 			signal_wake_up(p, 0);
 			spin_unlock_irqrestore(&p->sighand->siglock, flags);
@@ -91,7 +88,7 @@ int freeze_processes(void)
 			return todo;
 		}
 	} while(todo);
-	
+
 	printk( "|\n" );
 	BUG_ON(in_atomic());
 	return 0;
@@ -106,10 +103,7 @@ void thaw_processes(void)
 	do_each_thread(g, p) {
 		if (!freezeable(p))
 			continue;
-		if (p->flags & PF_FROZEN) {
-			p->flags &= ~PF_FROZEN;
-			wake_up_process(p);
-		} else
+		if (!thaw_process(p))
 			printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
 	} while_each_thread(g, p);
 
Index: linux-2.6.12/mm/vmscan.c
===================================================================
--- linux-2.6.12.orig/mm/vmscan.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/mm/vmscan.c	2005-06-25 05:01:28.000000000 +0000
@@ -1216,8 +1216,8 @@ static int kswapd(void *p)
 	order = 0;
 	for ( ; ; ) {
 		unsigned long new_order;
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+
+		try_to_freeze();
 
 		prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
 		new_order = pgdat->kswapd_max_order;
Index: linux-2.6.12/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -213,7 +213,7 @@ static inline int has_pending_signals(si
 fastcall void recalc_sigpending_tsk(struct task_struct *t)
 {
 	if (t->signal->group_stop_count > 0 ||
-	    (t->flags & PF_FREEZE) ||
+	    (freezing(t)) ||
 	    PENDING(&t->pending, &t->blocked) ||
 	    PENDING(&t->signal->shared_pending, &t->blocked))
 		set_tsk_thread_flag(t, TIF_SIGPENDING);
@@ -2231,8 +2231,7 @@ sys_rt_sigtimedwait(const sigset_t __use
 			current->state = TASK_INTERRUPTIBLE;
 			timeout = schedule_timeout(timeout);
 
-			if (current->flags & PF_FREEZE)
-				refrigerator(PF_FREEZE);
+			try_to_freeze();
 			spin_lock_irq(&current->sighand->siglock);
 			sig = dequeue_signal(current, &these, &info);
 			current->blocked = current->real_blocked;
Index: linux-2.6.12/mm/pdflush.c
===================================================================
--- linux-2.6.12.orig/mm/pdflush.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/mm/pdflush.c	2005-06-25 05:01:28.000000000 +0000
@@ -105,7 +105,7 @@ static int __pdflush(struct pdflush_work
 		spin_unlock_irq(&pdflush_lock);
 
 		schedule();
-		if (try_to_freeze(PF_FREEZE)) {
+		if (try_to_freeze()) {
 			spin_lock_irq(&pdflush_lock);
 			continue;
 		}
Index: linux-2.6.12/kernel/sched.c
===================================================================
--- linux-2.6.12.orig/kernel/sched.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/kernel/sched.c	2005-06-25 05:01:28.000000000 +0000
@@ -4174,8 +4174,7 @@ static int migration_thread(void * data)
 		struct list_head *head;
 		migration_req_t *req;
 
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 
 		spin_lock_irq(&rq->lock);
 
Index: linux-2.6.12/drivers/pcmcia/cs.c
===================================================================
--- linux-2.6.12.orig/drivers/pcmcia/cs.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/pcmcia/cs.c	2005-06-25 05:01:28.000000000 +0000
@@ -718,7 +718,7 @@ static int pccardd(void *__skt)
 		}
 
 		schedule();
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		if (!skt->thread)
 			break;
Index: linux-2.6.12/drivers/usb/core/hub.c
===================================================================
--- linux-2.6.12.orig/drivers/usb/core/hub.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/usb/core/hub.c	2005-06-25 05:01:28.000000000 +0000
@@ -2808,7 +2808,7 @@ static int hub_thread(void *__unused)
 	do {
 		hub_events();
 		wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list)); 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 	pr_debug ("%s: khubd exiting\n", usbcore_name);
Index: linux-2.6.12/drivers/input/serio/serio.c
===================================================================
--- linux-2.6.12.orig/drivers/input/serio/serio.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/input/serio/serio.c	2005-06-25 05:01:28.000000000 +0000
@@ -344,7 +344,7 @@ static int serio_thread(void *nothing)
 	do {
 		serio_handle_events();
 		wait_event_interruptible(serio_wait, !list_empty(&serio_event_list));
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 	printk(KERN_DEBUG "serio: kseriod exiting\n");
Index: linux-2.6.12/fs/jbd/journal.c
===================================================================
--- linux-2.6.12.orig/fs/jbd/journal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/jbd/journal.c	2005-06-25 05:01:28.000000000 +0000
@@ -167,7 +167,7 @@ loop:
 	}
 
 	wake_up(&journal->j_wait_done_commit);
-	if (current->flags & PF_FREEZE) {
+	if (freezing(current)) {
 		/*
 		 * The simpler the better. Flushing journal isn't a
 		 * good idea, because that depends on threads that may
@@ -175,7 +175,7 @@ loop:
 		 */
 		jbd_debug(1, "Now suspending kjournald\n");
 		spin_unlock(&journal->j_state_lock);
-		refrigerator(PF_FREEZE);
+		refrigerator();
 		spin_lock(&journal->j_state_lock);
 	} else {
 		/*
Index: linux-2.6.12/drivers/usb/storage/usb.c
===================================================================
--- linux-2.6.12.orig/drivers/usb/storage/usb.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/usb/storage/usb.c	2005-06-25 05:01:28.000000000 +0000
@@ -847,10 +847,8 @@ retry:
 		wait_event_interruptible_timeout(us->delay_wait,
 				test_bit(US_FLIDX_DISCONNECTING, &us->flags),
 				delay_use * HZ);
-		if (current->flags & PF_FREEZE) {
-			refrigerator(PF_FREEZE);
+		if (try_to_freeze())
 			goto retry;
-		}
 	}
 
 	/* If the device is still connected, perform the scanning */
Index: linux-2.6.12/drivers/ieee1394/ieee1394_core.c
===================================================================
--- linux-2.6.12.orig/drivers/ieee1394/ieee1394_core.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/ieee1394/ieee1394_core.c	2005-06-25 05:01:28.000000000 +0000
@@ -1041,10 +1041,8 @@ static int hpsbpkt_thread(void *__hi)
 
 	while (1) {
 		if (down_interruptible(&khpsbpkt_sig)) {
-			if (current->flags & PF_FREEZE) {
-				refrigerator(0);
+			if (try_to_freeze())
 				continue;
-			}
 			printk("khpsbpkt: received unexpected signal?!\n" );
 			break;
 		}
Index: linux-2.6.12/arch/i386/kernel/io_apic.c
===================================================================
--- linux-2.6.12.orig/arch/i386/kernel/io_apic.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/i386/kernel/io_apic.c	2005-06-25 05:01:28.000000000 +0000
@@ -573,7 +573,7 @@ static int balanced_irq(void *unused)
 	for ( ; ; ) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		time_remaining = schedule_timeout(time_remaining);
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		if (time_after(jiffies,
 				prev_balance_time+balanced_irq_interval)) {
 			do_irq_balance();
Index: linux-2.6.12/net/sunrpc/svcsock.c
===================================================================
--- linux-2.6.12.orig/net/sunrpc/svcsock.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/net/sunrpc/svcsock.c	2005-06-25 05:01:28.000000000 +0000
@@ -1185,8 +1185,8 @@ svc_recv(struct svc_serv *serv, struct s
 	arg->page_len = (pages-2)*PAGE_SIZE;
 	arg->len = (pages-1)*PAGE_SIZE;
 	arg->tail[0].iov_len = 0;
-	
-	try_to_freeze(PF_FREEZE);
+
+	try_to_freeze();
 	if (signalled())
 		return -EINTR;
 
@@ -1227,7 +1227,7 @@ svc_recv(struct svc_serv *serv, struct s
 
 		schedule_timeout(timeout);
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		spin_lock_bh(&serv->sv_lock);
 		remove_wait_queue(&rqstp->rq_wait, &wait);
Index: linux-2.6.12/drivers/ieee1394/nodemgr.c
===================================================================
--- linux-2.6.12.orig/drivers/ieee1394/nodemgr.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/ieee1394/nodemgr.c	2005-06-25 05:01:28.000000000 +0000
@@ -1510,7 +1510,7 @@ static int nodemgr_host_thread(void *__h
 
 		if (down_interruptible(&hi->reset_sem) ||
 		    down_interruptible(&nodemgr_serialize)) {
-			if (try_to_freeze(PF_FREEZE))
+			if (try_to_freeze())
 				continue;
 			printk("NodeMgr: received unexpected signal?!\n" );
 			break;
Index: linux-2.6.12/drivers/md/md.c
===================================================================
--- linux-2.6.12.orig/drivers/md/md.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/md/md.c	2005-06-25 05:01:28.000000000 +0000
@@ -2976,8 +2976,7 @@ static int md_thread(void * arg)
 		wait_event_interruptible_timeout(thread->wqueue,
 						 test_bit(THREAD_WAKEUP, &thread->flags),
 						 thread->timeout);
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 
 		clear_bit(THREAD_WAKEUP, &thread->flags);
 
Index: linux-2.6.12/fs/jfs/jfs_logmgr.c
===================================================================
--- linux-2.6.12.orig/fs/jfs/jfs_logmgr.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/jfs/jfs_logmgr.c	2005-06-25 05:01:28.000000000 +0000
@@ -2359,9 +2359,9 @@ int jfsIOWait(void *arg)
 			lbmStartIO(bp);
 			spin_lock_irq(&log_redrive_lock);
 		}
-		if (current->flags & PF_FREEZE) {
+		if (freezing(current)) {
 			spin_unlock_irq(&log_redrive_lock);
-			refrigerator(PF_FREEZE);
+			refrigerator();
 		} else {
 			add_wait_queue(&jfs_IO_thread_wait, &wq);
 			set_current_state(TASK_INTERRUPTIBLE);
Index: linux-2.6.12/fs/jfs/jfs_txnmgr.c
===================================================================
--- linux-2.6.12.orig/fs/jfs/jfs_txnmgr.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/jfs/jfs_txnmgr.c	2005-06-25 05:01:28.000000000 +0000
@@ -2788,9 +2788,9 @@ int jfs_lazycommit(void *arg)
 		/* In case a wakeup came while all threads were active */
 		jfs_commit_thread_waking = 0;
 
-		if (current->flags & PF_FREEZE) {
+		if (freezing(current)) {
 			LAZY_UNLOCK(flags);
-			refrigerator(PF_FREEZE);
+			refrigerator();
 		} else {
 			DECLARE_WAITQUEUE(wq, current);
 
@@ -2987,9 +2987,9 @@ int jfs_sync(void *arg)
 		/* Add anon_list2 back to anon_list */
 		list_splice_init(&TxAnchor.anon_list2, &TxAnchor.anon_list);
 
-		if (current->flags & PF_FREEZE) {
+		if (freezing(current)) {
 			TXN_UNLOCK();
-			refrigerator(PF_FREEZE);
+			refrigerator();
 		} else {
 			DECLARE_WAITQUEUE(wq, current);
 
Index: linux-2.6.12/arch/i386/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/i386/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/i386/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -608,10 +608,8 @@ int fastcall do_signal(struct pt_regs *r
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze)
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
Index: linux-2.6.12/fs/lockd/clntproc.c
===================================================================
--- linux-2.6.12.orig/fs/lockd/clntproc.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/lockd/clntproc.c	2005-06-25 05:01:28.000000000 +0000
@@ -313,7 +313,7 @@ static int nlm_wait_on_grace(wait_queue_
 	prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 	if (!signalled ()) {
 		schedule_timeout(NLMCLNT_GRACE_WAIT);
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		if (!signalled ())
 			status = 0;
 	}
Index: linux-2.6.12/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- linux-2.6.12.orig/fs/xfs/linux-2.6/xfs_buf.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/xfs/linux-2.6/xfs_buf.c	2005-06-25 05:01:28.000000000 +0000
@@ -1771,9 +1771,9 @@ xfsbufd(
 
 	INIT_LIST_HEAD(&tmp);
 	do {
-		if (unlikely(current->flags & PF_FREEZE)) {
+		if (unlikely(freezing(current))) {
 			xfsbufd_force_sleep = 1;
-			refrigerator(PF_FREEZE);
+			refrigerator();
 		} else {
 			xfsbufd_force_sleep = 0;
 		}
Index: linux-2.6.12/arch/x86_64/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/x86_64/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/x86_64/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -425,7 +425,7 @@ int do_signal(struct pt_regs *regs, sigs
 	if (!user_mode(regs))
 		return 1;
 
-	if (try_to_freeze(0))
+	if (try_to_freeze())
 		goto no_signal;
 
 	if (!oldset)
Index: linux-2.6.12/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- linux-2.6.12.orig/fs/xfs/linux-2.6/xfs_super.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/xfs/linux-2.6/xfs_super.c	2005-06-25 05:01:28.000000000 +0000
@@ -483,7 +483,7 @@ xfssyncd(
 		set_current_state(TASK_INTERRUPTIBLE);
 		timeleft = schedule_timeout(timeleft);
 		/* swsusp */
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		if (vfsp->vfs_flag & VFS_UMOUNT)
 			break;
 
Index: linux-2.6.12/arch/ppc/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/ppc/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/ppc/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -705,8 +705,7 @@ int do_signal(sigset_t *oldset, struct p
 	unsigned long frame, newsp;
 	int signr, ret;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(PF_FREEZE);
+	if (try_to_freeze()) {
 		signr = 0;
 		if (!signal_pending(current))
 			goto no_signal;
Index: linux-2.6.12/Documentation/power/kernel_threads.txt
===================================================================
--- linux-2.6.12.orig/Documentation/power/kernel_threads.txt	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/Documentation/power/kernel_threads.txt	2005-06-25 05:01:28.000000000 +0000
@@ -12,8 +12,7 @@ refrigerator. Code to do this looks like
 	do {
 		hub_events();
 		wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 from drivers/usb/core/hub.c::hub_thread()
Index: linux-2.6.12/arch/h8300/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/h8300/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/h8300/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -517,10 +517,8 @@ asmlinkage int do_signal(struct pt_regs 
 	if ((regs->ccr & 0x10))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze())
 		goto no_signal;
-	}
 
 	current->thread.esp0 = (unsigned long) regs;
 
Index: linux-2.6.12/arch/m32r/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/m32r/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/m32r/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -371,10 +371,8 @@ int do_signal(struct pt_regs *regs, sigs
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze()) 
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
Index: linux-2.6.12/fs/afs/kafsasyncd.c
===================================================================
--- linux-2.6.12.orig/fs/afs/kafsasyncd.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/afs/kafsasyncd.c	2005-06-25 05:01:28.000000000 +0000
@@ -116,7 +116,7 @@ static int kafsasyncd(void *arg)
 		remove_wait_queue(&kafsasyncd_sleepq, &myself);
 		set_current_state(TASK_RUNNING);
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		/* discard pending signals */
 		afs_discard_my_signals();
Index: linux-2.6.12/fs/afs/kafstimod.c
===================================================================
--- linux-2.6.12.orig/fs/afs/kafstimod.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/fs/afs/kafstimod.c	2005-06-25 05:01:28.000000000 +0000
@@ -91,7 +91,7 @@ static int kafstimod(void *arg)
 			complete_and_exit(&kafstimod_dead, 0);
 		}
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		/* discard pending signals */
 		afs_discard_my_signals();
Index: linux-2.6.12/Documentation/power/swsusp.txt
===================================================================
--- linux-2.6.12.orig/Documentation/power/swsusp.txt	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/Documentation/power/swsusp.txt	2005-06-25 05:01:28.000000000 +0000
@@ -164,8 +164,7 @@ place where the thread is safe to be fro
 should be held at that point and it must be safe to sleep there), and
 add:
 
-            if (current->flags & PF_FREEZE)
-                    refrigerator(PF_FREEZE);
+            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.
Index: linux-2.6.12/arch/frv/kernel/signal.c
===================================================================
--- linux-2.6.12.orig/arch/frv/kernel/signal.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/arch/frv/kernel/signal.c	2005-06-25 05:01:28.000000000 +0000
@@ -536,10 +536,8 @@ int do_signal(struct pt_regs *regs, sigs
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze())
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
Index: linux-2.6.12/net/rxrpc/krxtimod.c
===================================================================
--- linux-2.6.12.orig/net/rxrpc/krxtimod.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/net/rxrpc/krxtimod.c	2005-06-25 05:01:28.000000000 +0000
@@ -90,7 +90,7 @@ static int krxtimod(void *arg)
 			complete_and_exit(&krxtimod_dead, 0);
 		}
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		/* discard pending signals */
 		rxrpc_discard_my_signals();
Index: linux-2.6.12/net/rxrpc/krxiod.c
===================================================================
--- linux-2.6.12.orig/net/rxrpc/krxiod.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/net/rxrpc/krxiod.c	2005-06-25 05:01:28.000000000 +0000
@@ -138,7 +138,7 @@ static int rxrpc_krxiod(void *arg)
 
 		_debug("### End Work");
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
                 /* discard pending signals */
 		rxrpc_discard_my_signals();
Index: linux-2.6.12/net/rxrpc/krxsecd.c
===================================================================
--- linux-2.6.12.orig/net/rxrpc/krxsecd.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/net/rxrpc/krxsecd.c	2005-06-25 05:01:28.000000000 +0000
@@ -107,7 +107,7 @@ static int rxrpc_krxsecd(void *arg)
 
 		_debug("### End Inbound Calls");
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
                 /* discard pending signals */
 		rxrpc_discard_my_signals();
Index: linux-2.6.12/drivers/media/dvb/dvb-core/dvb_frontend.c
===================================================================
--- linux-2.6.12.orig/drivers/media/dvb/dvb-core/dvb_frontend.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/media/dvb/dvb-core/dvb_frontend.c	2005-06-25 05:01:28.000000000 +0000
@@ -391,8 +391,7 @@ static int dvb_frontend_thread(void *dat
 			break;
 		}
 
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 
 		if (down_interruptible(&fepriv->sem))
 			break;
Index: linux-2.6.12/drivers/media/video/msp3400.c
===================================================================
--- linux-2.6.12.orig/drivers/media/video/msp3400.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/media/video/msp3400.c	2005-06-25 05:01:28.000000000 +0000
@@ -750,8 +750,7 @@ static int msp34xx_sleep(struct msp3400c
 #endif
 		}
 	}
-	if (current->flags & PF_FREEZE)
-		refrigerator(PF_FREEZE);
+	try_to_freeze();
 	remove_wait_queue(&msp->wq, &wait);
 	return msp->restart;
 }
Index: linux-2.6.12/drivers/net/irda/stir4200.c
===================================================================
--- linux-2.6.12.orig/drivers/net/irda/stir4200.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/net/irda/stir4200.c	2005-06-25 05:01:28.000000000 +0000
@@ -763,7 +763,7 @@ static int stir_transmit_thread(void *ar
 	{
 #ifdef CONFIG_PM
 		/* if suspending, then power off and wait */
-		if (unlikely(current->flags & PF_FREEZE)) {
+		if (unlikely(freezing(current))) {
 			if (stir->receiving)
 				receive_stop(stir);
 			else
@@ -771,7 +771,7 @@ static int stir_transmit_thread(void *ar
 
 			write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);
 
-			refrigerator(PF_FREEZE);
+			refrigerator();
 
 			if (change_speed(stir, stir->speed))
 				break;
Index: linux-2.6.12/drivers/input/gameport/gameport.c
===================================================================
--- linux-2.6.12.orig/drivers/input/gameport/gameport.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/input/gameport/gameport.c	2005-06-25 05:01:28.000000000 +0000
@@ -439,7 +439,7 @@ static int gameport_thread(void *nothing
 	do {
 		gameport_handle_events();
 		wait_event_interruptible(gameport_wait, !list_empty(&gameport_event_list));
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 	} while (!signal_pending(current));
 
 	printk(KERN_DEBUG "gameport: kgameportd exiting\n");
Index: linux-2.6.12/drivers/usb/gadget/file_storage.c
===================================================================
--- linux-2.6.12.orig/drivers/usb/gadget/file_storage.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/usb/gadget/file_storage.c	2005-06-25 05:01:28.000000000 +0000
@@ -1554,8 +1554,7 @@ static int sleep_thread(struct fsg_dev *
 	rc = wait_event_interruptible(fsg->thread_wqh,
 			fsg->thread_wakeup_needed);
 	fsg->thread_wakeup_needed = 0;
-	if (current->flags & PF_FREEZE)
-		refrigerator(PF_FREEZE);
+	try_to_freeze();
 	return (rc ? -EINTR : 0);
 }
 
Index: linux-2.6.12/drivers/pnp/pnpbios/core.c
===================================================================
--- linux-2.6.12.orig/drivers/pnp/pnpbios/core.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/pnp/pnpbios/core.c	2005-06-25 05:01:28.000000000 +0000
@@ -182,7 +182,7 @@ static int pnp_dock_thread(void * unused
 		msleep_interruptible(2000);
 
 		if(signal_pending(current)) {
-			if (try_to_freeze(PF_FREEZE))
+			if (try_to_freeze())
 				continue;
 			break;
 		}
Index: linux-2.6.12/drivers/net/wireless/airo.c
===================================================================
--- linux-2.6.12.orig/drivers/net/wireless/airo.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/net/wireless/airo.c	2005-06-25 05:01:28.000000000 +0000
@@ -2918,7 +2918,7 @@ static int airo_thread(void *data) {
 			flush_signals(current);
 
 		/* make swsusp happy with our thread */
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 
 		if (test_bit(JOB_DIE, &ai->flags))
 			break;
Index: linux-2.6.12/drivers/macintosh/therm_adt746x.c
===================================================================
--- linux-2.6.12.orig/drivers/macintosh/therm_adt746x.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/macintosh/therm_adt746x.c	2005-06-25 05:01:28.000000000 +0000
@@ -328,9 +328,7 @@ static int monitor_task(void *arg)
 	struct thermostat* th = arg;
 
 	while(!kthread_should_stop()) {
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
-
+		try_to_freeze();
 		msleep_interruptible(2000);
 
 #ifndef DEBUG
Index: linux-2.6.12/drivers/net/irda/sir_kthread.c
===================================================================
--- linux-2.6.12.orig/drivers/net/irda/sir_kthread.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/net/irda/sir_kthread.c	2005-06-25 05:01:28.000000000 +0000
@@ -135,8 +135,7 @@ static int irda_thread(void *startup)
 		remove_wait_queue(&irda_rq_queue.kick, &wait);
 
 		/* make swsusp happy with our thread */
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 
 		run_irda_queue();
 	}
Index: linux-2.6.12/drivers/media/video/video-buf-dvb.c
===================================================================
--- linux-2.6.12.orig/drivers/media/video/video-buf-dvb.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/media/video/video-buf-dvb.c	2005-06-25 05:01:28.000000000 +0000
@@ -62,8 +62,7 @@ static int videobuf_dvb_thread(void *dat
 			break;
 		if (kthread_should_stop())
 			break;
-		if (current->flags & PF_FREEZE)
-			refrigerator(PF_FREEZE);
+		try_to_freeze();
 
 		/* feed buffer data to demux */
 		if (buf->state == STATE_DONE)
Index: linux-2.6.12/drivers/net/8139too.c
===================================================================
--- linux-2.6.12.orig/drivers/net/8139too.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/net/8139too.c	2005-06-25 05:01:28.000000000 +0000
@@ -1606,7 +1606,7 @@ static int rtl8139_thread (void *data)
 		do {
 			timeout = interruptible_sleep_on_timeout (&tp->thr_wait, timeout);
 			/* make swsusp happy with our thread */
-			try_to_freeze(PF_FREEZE);
+			try_to_freeze();
 		} while (!signal_pending (current) && (timeout > 0));
 
 		if (signal_pending (current)) {
Index: linux-2.6.12/drivers/w1/w1.c
===================================================================
--- linux-2.6.12.orig/drivers/w1/w1.c	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/drivers/w1/w1.c	2005-06-25 05:01:28.000000000 +0000
@@ -646,7 +646,7 @@ static int w1_control(void *data)
 	while (!control_needs_exit || have_to_wait) {
 		have_to_wait = 0;
 
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		msleep_interruptible(w1_timeout * 1000);
 
 		if (signal_pending(current))
@@ -725,7 +725,7 @@ int w1_process(void *data)
 	allow_signal(SIGTERM);
 
 	while (!test_bit(W1_MASTER_NEED_EXIT, &dev->flags)) {
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		msleep_interruptible(w1_timeout * 1000);
 
 		if (signal_pending(current))
Index: linux-2.6.12/include/linux/sched.h
===================================================================
--- linux-2.6.12.orig/include/linux/sched.h	2005-06-25 05:01:26.000000000 +0000
+++ linux-2.6.12/include/linux/sched.h	2005-06-25 05:41:28.000000000 +0000
@@ -1245,33 +1245,78 @@ extern void normalize_rt_tasks(void);
 
 #endif
 
-/* try_to_freeze
- *
- * Checks whether we need to enter the refrigerator
- * and returns 1 if we did so.
- */
 #ifdef CONFIG_PM
-extern void refrigerator(unsigned long);
+/*
+ * Check if a process has been frozen
+ */
+static inline int frozen(struct task_struct *p)
+{
+	return p->flags & PF_FROZEN;
+}
+
+/*
+ * Check if there is a request to freeze a process
+ */
+static inline int freezing(struct task_struct *p)
+{
+	return p->flags & PF_FREEZE;
+}
+
+/*
+ * Request that a process be frozen
+ * FIXME: SMP problem. We may not modify other process' flags!
+ */
+static inline void freeze(struct task_struct *p)
+{
+	p->flags |= PF_FREEZE;
+}
+
+/*
+ * Wake up a frozen process
+ */
+static inline int thaw_process(struct task_struct *p)
+{
+	if (frozen(p)) {
+		p->flags &= ~PF_FROZEN;
+		wake_up_process(p);
+		return 1;
+	}
+	return 0;
+}
+
+/*
+ * freezing is complete, mark process as frozen
+ */
+static inline void frozen_process(struct task_struct *p)
+{
+	p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN;
+}
+
+extern void refrigerator(void);
 extern int freeze_processes(void);
 extern void thaw_processes(void);
 
-static inline int try_to_freeze(unsigned long refrigerator_flags)
+static inline int try_to_freeze(void)
 {
-	if (unlikely(current->flags & PF_FREEZE)) {
-		refrigerator(refrigerator_flags);
+	if (freezing(current)) {
+		refrigerator();
 		return 1;
 	} else
 		return 0;
 }
 #else
-static inline void refrigerator(unsigned long flag) {}
+static inline int frozen(struct task_struct *p) { return 0; }
+static inline int freezing(struct task_struct *p) { return 0; }
+static inline void freeze(struct task_struct *p) { BUG(); }
+static inline int thaw_process(struct task_struct *p) { return 1; }
+static inline void frozen_process(struct task_struct *p) { BUG(); }
+
+static inline void refrigerator(void) {}
 static inline int freeze_processes(void) { BUG(); return 0; }
 static inline void thaw_processes(void) {}
 
-static inline int try_to_freeze(unsigned long refrigerator_flags)
-{
-	return 0;
-}
+static inline int try_to_freeze(void) { return 0; }
+
 #endif /* CONFIG_PM */
 #endif /* __KERNEL__ */
 
-
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