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

commented with <<<< inside

Approach seems okay... Perhaps better place is something like
kernel/freezer.c so it stays separate file? It is not really scheduler
core, and it is only conditionally compiled...

There is already lots of other conditional code in kernel/sched.c and thisis just one function. It is scheduler like and uses scheduler variablessince it suspends a process. So lets move it there.

I think this is as far as I can take it. Could you test this and seeif it works okay?


For suspension for migration do:

1. down(&freezer_sem)

2. Signal processes to sleep (see kernel/power/process.c). Basically
   set the TIF_FREEZE and may be do the fake signal thing.

3. If all processes have PF_FROZEN set then they are asleep.

4. Do migration things

5. complete_all(&thaw)

6. up(&freezer_sem)

----
Revise handling of freezing in the suspend code

The current suspend code modifies thread flags from outside the context of process.
This creates a SMP race.

The patch fixes that by introducing a TIF_FREEZE flag (for all arches). Also

- Uses a completion handler instead of waiting in a schedule loop in the refrigerator.

- Introduces a semaphore freezer_sem to provide a way that multiple kernel
  subsystems can use the freezing ability without interfering with one another.

- Include necessary definitions for the migration code if CONFIG_MIGRATE is set.

- Removes PF_FREEZE

Signed-off-by: Christoph Lameter <[email protected]>

Index: linux-2.6.12/include/linux/sched.h
===================================================================
--- linux-2.6.12.orig/include/linux/sched.h	2005-06-27 05:20:15.000000000 +0000
+++ linux-2.6.12/include/linux/sched.h	2005-06-27 05:33:46.000000000 +0000
@@ -804,7 +804,6 @@ do { if (atomic_dec_and_test(&(tsk)->usa
 #define PF_MEMALLOC	0x00000800	/* Allocating memory */
 #define PF_FLUSHER	0x00001000	/* responsible for disk writeback */
 #define PF_USED_MATH	0x00002000	/* if unset the fpu must be initialized before use */
-#define PF_FREEZE	0x00004000	/* this task is being frozen for suspend now */
 #define PF_NOFREEZE	0x00008000	/* this thread should not be frozen */
 #define PF_FROZEN	0x00010000	/* frozen for system suspend */
 #define PF_FSTRANS	0x00020000	/* inside a filesystem transaction */
@@ -1265,78 +1264,37 @@ extern void normalize_rt_tasks(void);

#endif-#ifdef CONFIG_PM

-/*
- * 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;
-}
+#if defined(CONFIG_PM) || defined(CONFIG_MIGRATE)

<<<< why not to make a single option CONFIG_REFRIGERATOR? It looks to bea more robust way, since there are multiple users of it.

+extern struct semaphore freezer_sem;
+extern struct completion thaw;

-/*

- * 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;
-}
+extern void refrigerator(void);

-/*

- * freezing is complete, mark process as frozen
- */
-static inline void frozen_process(struct task_struct *p)
+static inline int freezing(struct task_struct *p)
 {
-	p->flags = (p->flags & ~PF_FREEZE) | PF_FROZEN;
+	return test_ti_thread_flag(p->thread_info, TIF_FREEZE);
 }

-extern void refrigerator(void);

-extern int freeze_processes(void);
-extern void thaw_processes(void);
-
 static inline int try_to_freeze(void)
 {
-	if (freezing(current)) {
+	if (test_thread_flag(TIF_FREEZE)) {
 		refrigerator();
 		return 1;
 	} else
 		return 0;
 }
 #else
-static inline int frozen(struct task_struct *p) { return 0; }
+static inline void refrigerator(void) {}
 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 int try_to_freeze(void) { return 0; }
+#endif

-static inline void refrigerator(void) {}

+#ifdef CONFIG_PM

<<<< is it intentionaly? or you just lost CONFIG_MIGRATE?

+extern int freeze_processes(void);
+extern void thaw_processes(void);
+#else
 static inline int freeze_processes(void) { BUG(); return 0; }
 static inline void thaw_processes(void) {}
-
-static inline int try_to_freeze(void) { return 0; }
-
 #endif /* CONFIG_PM */
 #endif /* __KERNEL__ */

Index: linux-2.6.12/kernel/power/process.c

===================================================================
--- linux-2.6.12.orig/kernel/power/process.c	2005-06-27 05:20:15.000000000 +0000
+++ linux-2.6.12/kernel/power/process.c	2005-06-27 15:07:46.000000000 +0000
@@ -18,7 +18,6 @@
  */
 #define TIMEOUT	(6 * HZ)

-

 static inline int freezeable(struct task_struct * p)
 {

if ((p == current) ||@@ -31,28 +30,6 @@ static inline int freezeable(struct task

 	return 1;
 }

-/* Refrigerator is place where frozen processes are stored :-). */

-void refrigerator(void)
-{
-	/* Hmm, should we be allowed to suspend when there are realtime
-	   processes around? */
-	long save;
-	save = current->state;
-	current->state = TASK_UNINTERRUPTIBLE;
-	pr_debug("%s entered refrigerator\n", current->comm);
-	printk("=");
-
-	frozen_process(current);
-	spin_lock_irq(&current->sighand->siglock);
-	recalc_sigpending(); /* We sent fake signal, clean it up */
-	spin_unlock_irq(&current->sighand->siglock);
-
-	while (frozen(current))
-		schedule();
-	pr_debug("%s left refrigerator\n", current->comm);
-	current->state = save;
-}
-
 /* 0 = success, else # of processes that we failed to stop */
 int freeze_processes(void)
 {
@@ -60,6 +37,7 @@ int freeze_processes(void)
 	unsigned long start_time;
 	struct task_struct *g, *p;

+ down(&freezer_sem);

 	printk( "Stopping tasks: " );
 	start_time = jiffies;
 	do {
@@ -69,12 +47,12 @@ int freeze_processes(void)
 			unsigned long flags;
 			if (!freezeable(p))
 				continue;
-			if ((frozen(p)) ||
+			if ((p->flags & PF_FROZEN) ||
 			    (p->state == TASK_TRACED) ||
 			    (p->state == TASK_STOPPED))
 				continue;

- freeze(p);

+			set_thread_flag(TIF_FREEZE);
 			spin_lock_irqsave(&p->sighand->siglock, flags);
 			signal_wake_up(p, 0);
 			spin_unlock_irqrestore(&p->sighand->siglock, flags);
@@ -96,20 +74,6 @@ int freeze_processes(void)

void thaw_processes(void)

 {
-	struct task_struct *g, *p;
-
-	printk( "Restarting tasks..." );
-	read_lock(&tasklist_lock);
-	do_each_thread(g, p) {
-		if (!freezeable(p))
-			continue;
-		if (!thaw_process(p))
-			printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
-	} while_each_thread(g, p);
-
-	read_unlock(&tasklist_lock);
-	schedule();
-	printk( " done\n" );
+	complete_all(&thaw);
+	up(&freezer_sem);
 }
-
-EXPORT_SYMBOL(refrigerator);
Index: linux-2.6.12/include/asm-x86_64/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-x86_64/thread_info.h	2005-06-27 05:20:15.000000000 +0000
+++ linux-2.6.12/include/asm-x86_64/thread_info.h	2005-06-27 05:37:24.000000000 +0000
@@ -108,6 +108,7 @@ static inline struct thread_info *stack_
 #define TIF_FORK		18	/* ret_from_fork */
 #define TIF_ABI_PENDING		19
 #define TIF_MEMDIE		20
+#define TIF_FREEZE		21	/* Freeze process */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-ia64/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-ia64/thread_info.h	2005-06-27 05:20:15.000000000 +0000
+++ linux-2.6.12/include/asm-ia64/thread_info.h	2005-06-27 05:26:12.000000000 +0000
@@ -76,6 +76,7 @@ struct thread_info {
 #define TIF_SIGDELAYED		5	/* signal delayed from MCA/INIT/NMI/PMI context */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17
+#define TIF_FREEZE		18	/* Freeze process */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)

 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
Index: linux-2.6.12/include/asm-i386/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-i386/thread_info.h	2005-06-27 05:20:15.000000000 +0000
+++ linux-2.6.12/include/asm-i386/thread_info.h	2005-06-27 05:25:49.000000000 +0000
@@ -143,6 +143,7 @@ register unsigned long current_stack_poi
 #define TIF_SECCOMP		8	/* secure computing */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17
+#define TIF_FREEZE		18	/* Freeze thread */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-xtensa/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-xtensa/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-xtensa/thread_info.h	2005-06-27 05:36:54.000000000 +0000
@@ -118,6 +118,7 @@ static inline struct thread_info *curren
 #define TIF_SINGLESTEP		4	/* restore singlestep on return to user mode */
 #define TIF_IRET		5	/* return with iret */
 #define TIF_MEMDIE		6
+#define TIF_FREEZE		7
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

Index: linux-2.6.12/include/asm-h8300/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-h8300/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-h8300/thread_info.h	2005-06-27 05:25:25.000000000 +0000
@@ -94,6 +94,7 @@ static inline struct thread_info *curren
 #define TIF_POLLING_NRFLAG	4	/* true if poll_idle() is polling
 					   TIF_NEED_RESCHED */
 #define TIF_MEMDIE		5
+#define TIF_FREEZE		6

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-ppc/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-ppc/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-ppc/thread_info.h	2005-06-27 05:28:53.000000000 +0000
@@ -80,6 +80,7 @@ static inline struct thread_info *curren
 #define TIF_MEMDIE		5
 #define TIF_SYSCALL_AUDIT       6       /* syscall auditing active */
 #define TIF_SECCOMP             7      /* secure computing */
+#define TIF_FREEZE		8

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-sh64/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-sh64/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-sh64/thread_info.h	2005-06-27 05:35:02.000000000 +0000
@@ -80,6 +80,7 @@ static inline struct thread_info *curren
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_MEMDIE		4
+#define TIF_FREEZE		5

#endif /* __KERNEL__ */

Index: linux-2.6.12/include/asm-alpha/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-alpha/thread_info.h	2005-06-17 19:48:29.000000000 +0000
+++ linux-2.6.12/include/asm-alpha/thread_info.h	2005-06-27 05:23:06.000000000 +0000
@@ -78,6 +78,7 @@ register struct thread_info *__current_t
 #define TIF_UAC_NOFIX		7
 #define TIF_UAC_SIGBUS		8
 #define TIF_MEMDIE		9
+#define TIF_FREEZE		10

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-sparc/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-sparc/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-sparc/thread_info.h	2005-06-27 05:35:23.000000000 +0000

@@ -139,6 +139,7 @@ BTFIXUPDEF_CALL(void, free_thread_info,#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling

 					 * TIF_NEED_RESCHED */
 #define TIF_MEMDIE		10
+#define TIF_FREEZE		11

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-frv/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-frv/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-frv/thread_info.h	2005-06-27 05:25:02.000000000 +0000
@@ -133,6 +133,7 @@ register struct thread_info *__current_t
 #define TIF_IRET		5	/* return with iret */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17	/* OOM killer killed process */
+#define TIF_FREEZE		18

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-parisc/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-parisc/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-parisc/thread_info.h	2005-06-27 05:28:34.000000000 +0000
@@ -64,6 +64,7 @@ struct thread_info {
 #define TIF_POLLING_NRFLAG	4	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_32BIT               5       /* 32 bit binary */
 #define TIF_MEMDIE		6
+#define TIF_FREEZE		7

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-m68knommu/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-m68knommu/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-m68knommu/thread_info.h	2005-06-27 05:27:13.000000000 +0000
@@ -91,6 +91,7 @@ static inline struct thread_info *curren
 #define TIF_POLLING_NRFLAG	4	/* true if poll_idle() is polling
 					   TIF_NEED_RESCHED */
 #define TIF_MEMDIE		5
+#define TIF_FREEZE		6

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-m68k/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-m68k/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-m68k/thread_info.h	2005-06-27 05:26:49.000000000 +0000
@@ -49,6 +49,7 @@ struct thread_info {
 #define TIF_SIGPENDING		3	/* signal pending */
 #define TIF_NEED_RESCHED	4	/* rescheduling necessary */
 #define TIF_MEMDIE		5
+#define TIF_FREEZE		6

extern int thread_flag_fixme(void);Index: linux-2.6.12/include/asm-sh/thread_info.h

===================================================================
--- linux-2.6.12.orig/include/asm-sh/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-sh/thread_info.h	2005-06-27 05:34:43.000000000 +0000
@@ -84,6 +84,7 @@ static inline struct thread_info *curren
 #define TIF_USEDFPU		16	/* FPU was used by this task this quantum (SMP) */
 #define TIF_POLLING_NRFLAG	17	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		18
+#define TIF_FREEZE		19
 #define TIF_USERSPACE		31	/* true if FS sets userspace */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

Index: linux-2.6.12/include/asm-s390/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-s390/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-s390/thread_info.h	2005-06-27 05:34:19.000000000 +0000
@@ -102,6 +102,7 @@ static inline struct thread_info *curren
 					   TIF_NEED_RESCHED */

#define TIF_31BIT 18 /* 32bit process */#define TIF_MEMDIE 19

+#define TIF_FREEZE		20

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-arm/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-arm/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-arm/thread_info.h	2005-06-27 05:23:34.000000000 +0000
@@ -132,6 +132,7 @@ extern void iwmmxt_task_release(struct t
 #define TIF_POLLING_NRFLAG	16
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18
+#define TIF_FREEZE		19

#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)

 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
Index: linux-2.6.12/include/asm-v850/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-v850/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-v850/thread_info.h	2005-06-27 05:36:25.000000000 +0000
@@ -85,6 +85,7 @@ struct thread_info {
 #define TIF_POLLING_NRFLAG	4	/* true if poll_idle() is polling
 					   TIF_NEED_RESCHED */
 #define TIF_MEMDIE		5
+#define TIF_FREEZE		6

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-mips/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-mips/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-mips/thread_info.h	2005-06-27 05:27:41.000000000 +0000
@@ -117,6 +117,7 @@ register struct thread_info *__current_t
 #define TIF_USEDFPU		16	/* FPU was used by this task this quantum (SMP) */
 #define TIF_POLLING_NRFLAG	17	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		18
+#define TIF_FREEZE		19
 #define TIF_SYSCALL_TRACE	31	/* syscall trace active */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

Index: linux-2.6.12/include/asm-cris/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-cris/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-cris/thread_info.h	2005-06-27 05:24:28.000000000 +0000
@@ -86,6 +86,7 @@ struct thread_info {
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17
+#define TIF_FREEZE		18

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-arm26/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-arm26/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-arm26/thread_info.h	2005-06-27 05:24:02.000000000 +0000
@@ -127,6 +127,7 @@ extern void free_thread_info(struct thre
 #define TIF_USED_FPU		16
 #define TIF_POLLING_NRFLAG	17
 #define TIF_MEMDIE		18
+#define TIF_FREEZE		19

#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)

 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
Index: linux-2.6.12/include/asm-sparc64/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-sparc64/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-sparc64/thread_info.h	2005-06-27 05:35:45.000000000 +0000
@@ -229,6 +229,7 @@ register struct thread_info *current_thr
  */
 #define TIF_ABI_PENDING		12
 #define TIF_MEMDIE		13
+#define TIF_FREEZE		14

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-m32r/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-m32r/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-m32r/thread_info.h	2005-06-27 05:26:33.000000000 +0000
@@ -156,6 +156,7 @@ static inline unsigned int get_thread_fa
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 					/* 31..28 fault code */
 #define TIF_MEMDIE		17
+#define TIF_FREEZE		18

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)

 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
Index: linux-2.6.12/include/asm-ppc64/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-ppc64/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-ppc64/thread_info.h	2005-06-27 05:29:13.000000000 +0000
@@ -102,6 +102,7 @@ static inline struct thread_info *curren
 #define TIF_SINGLESTEP		9	/* singlestepping active */
 #define TIF_MEMDIE		10
 #define TIF_SECCOMP		11	/* secure computing */
+#define TIF_FREEZE		12

/* as above, but as bit values */

 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
Index: linux-2.6.12/include/asm-um/thread_info.h
===================================================================
--- linux-2.6.12.orig/include/asm-um/thread_info.h	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/include/asm-um/thread_info.h	2005-06-27 05:36:07.000000000 +0000
@@ -72,6 +72,7 @@ static inline struct thread_info *curren
 #define TIF_RESTART_BLOCK 	4
 #define TIF_MEMDIE	 	5
 #define TIF_SYSCALL_AUDIT	6
+#define TIF_FREEZE		7

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)

 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
Index: linux-2.6.12/kernel/sched.c
===================================================================
--- linux-2.6.12.orig/kernel/sched.c	2005-06-27 02:23:01.000000000 +0000
+++ linux-2.6.12/kernel/sched.c	2005-06-27 15:08:19.000000000 +0000
@@ -5203,6 +5203,25 @@ void __init sched_init(void)
 	init_idle(current, smp_processor_id());
 }

+#if defined(CONFIG_PM) || defined(CONFIG_MIGRATE)

+DECLARE_MUTEX(freezer_sem);
+DECLARE_COMPLETION(thaw);
+
+void refrigerator(void)
+{
+	current->flags |= PF_FROZEN;
+	clear_thread_flag(TIF_FREEZE);
+	/* A fake signal 0 may have been sent. Recalculate sigpending */
+	spin_lock_irq(&current->sighand->siglock);
+	recalc_sigpending();
+	spin_unlock_irq(&current->sighand->siglock);
+	wait_for_completion(&thaw);
+	current->flags &= ~PF_FROZEN;

<<<< I still think this refrigerator is racy with freeze_processes():
<<<< scenarios:
<<<< scenario 1
<<<<
task1 -> freeze_processes():			taskXXX ->refrigerator()
  checked (task->flags & PF_FROZEN) == 0	cur->flags |= PF_FROZEN
						clear TIF_FREEZE
						<sleep on thaw>
  set TIF_FREEZING
						clear PF_FROZEN

<<<< so the task awakes with TIF_FREEZE flag set!!!

<<<< scenario 2

<<<< look at error path in freeze_processes (on timeout), it is brokenas well. You need to wakeup tasks there...


<<<< ------------------------------

+}
+EXPORT_SYMBOL(refrigerator);
+#endif
+
+
 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 void __might_sleep(char *file, int line)
 {
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Follow-Ups:
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Pavel Machek <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>

References:
- [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Pavel Machek <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Pavel Machek <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Pavel Machek <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Linus Torvalds <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Pavel Machek <[email protected]>
- Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
  - From: Christoph Lameter <[email protected]>

Prev by Date: tungsten t5 doesn't sync anymore with kernel 2.6.12
Next by Date: Re: [PATCH] de_thread: eliminate unneccessary sighand locking
Previous by thread: Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
Next by thread: Re: [RFC] Fix SMP brokenness for PF_FREEZE and make freezing usable for other purposes
Index(es):
- Date
- Thread

[Index of Archives] [Kernel Newbies] [Netfilter] [Bugtraq] [Photo] [Stuff] [Gimp] [Yosemite News] [MIPS Linux] [ARM Linux] [Linux Security] [Linux RAID] [Video 4 Linux] [Linux for the blind] [Linux Resources]