Re: [PATCH -mm 2/2] Introduce freezer flags

From: Rafael J. Wysocki
Date: Fri Apr 27 2007 - 18:53:26 EST

On Saturday, 28 April 2007 00:07, Pavel Machek wrote:
> Hi!
>
> > > > > +#ifdef CONFIG_FREEZER
> > > > > + /* Used by the process freezer, defined in freezer.h */
> > > > > + unsigned int freezer_flags;
> > > >
> > > > unsigned long freezer_flags; ??
> > >
> > > I guess so.
> >
> > Still, on x86_64, for example, we'll waste 4 bytes by using 'unsigned long'
> > here, which I wouldn't like to do.
> >
> > Is it acceptable to use explicit type casting in set_bit() and friends?
>
> I'm afraid set_bit & friends are only defined on unsigned long.

On x86_64 they are defined on anything, even on huge bitmaps.

> You can cast, but you may run into some nasty surprise... like damaging
> surrounding bytes on 64-bit architectures != x86_64.

Let's use unsigned long, then, but I'm not really happy with that.

---
From: Rafael J. Wysocki <rjw@xxxxxxx>

Move all of the freezer-related flags to a separate field in task_struct and
introduce functions to operate them using set_bit() etc.

Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
---
Documentation/power/kernel_threads.txt | 2 -
Documentation/power/swsusp.txt | 4 +-
arch/i386/kernel/apm.c | 2 -
drivers/block/loop.c | 2 -
drivers/char/apm-emulation.c | 6 +--
drivers/ieee1394/ieee1394_core.c | 2 -
drivers/md/md.c | 2 -
drivers/mmc/card/queue.c | 3 +
drivers/mtd/mtd_blkdevs.c | 3 +
drivers/scsi/libsas/sas_scsi_host.c | 2 -
drivers/scsi/scsi_error.c | 2 -
drivers/usb/storage/usb.c | 2 -
include/asm-arm/thread_info.h | 2 -
include/asm-blackfin/thread_info.h | 2 -
include/asm-frv/thread_info.h | 2 -
include/asm-i386/thread_info.h | 2 -
include/asm-ia64/thread_info.h | 2 -
include/asm-mips/thread_info.h | 2 -
include/asm-powerpc/thread_info.h | 2 -
include/asm-sh/thread_info.h | 2 -
include/asm-x86_64/thread_info.h | 2 -
include/linux/freezer.h | 63 +++++++++++++++++++++++++++------
include/linux/sched.h | 8 ++--
kernel/fork.c | 5 ++
kernel/freezer.c | 10 ++---
kernel/kthread.c | 3 +
kernel/rcutorture.c | 4 +-
kernel/sched.c | 2 -
kernel/softirq.c | 2 -
kernel/softlockup.c | 2 -
kernel/workqueue.c | 2 -
31 files changed, 90 insertions(+), 61 deletions(-)

Index: linux-2.6.21-rc7-mm2/include/linux/sched.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/linux/sched.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/linux/sched.h 2007-04-28 00:45:20.000000000 +0200
@@ -1006,7 +1006,10 @@ struct task_struct {
/* Deadlock detection and priority inheritance handling */
struct rt_mutex_waiter *pi_blocked_on;
#endif
-
+#ifdef CONFIG_FREEZER
+ /* Used by the process freezer, defined in freezer.h */
+ unsigned long freezer_flags;
+#endif
#ifdef CONFIG_DEBUG_MUTEXES
/* mutex deadlock detection */
struct mutex_waiter *blocked_on;
@@ -1189,8 +1192,6 @@ static inline void put_task_struct(struc
#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_NOFREEZE 0x00008000 /* this thread should not be frozen */
-#define PF_FROZEN 0x00010000 /* frozen for system suspend */
#define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */
#define PF_KSWAPD 0x00040000 /* I am kswapd */
#define PF_SWAPOFF 0x00080000 /* I am in swapoff */
@@ -1202,7 +1203,6 @@ static inline void put_task_struct(struc
#define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
-#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezeable */

/*
* Only the _current_ task can read/write to tsk->flags, but other
Index: linux-2.6.21-rc7-mm2/include/asm-arm/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-arm/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-arm/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -147,7 +147,6 @@ extern void iwmmxt_task_switch(struct th
#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)
@@ -155,7 +154,6 @@ extern void iwmmxt_task_switch(struct th
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
-#define _TIF_FREEZE (1 << TIF_FREEZE)

/*
* Change these and you break ASM code in entry-common.S
Index: linux-2.6.21-rc7-mm2/include/asm-blackfin/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-blackfin/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-blackfin/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -125,7 +125,6 @@ static inline struct thread_info *curren
TIF_NEED_RESCHED */
#define TIF_MEMDIE 5
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
-#define TIF_FREEZE 7 /* is freezing for suspend */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -134,7 +133,6 @@ static inline struct thread_info *curren
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
-#define _TIF_FREEZE (1<<TIF_FREEZE)

#define _TIF_WORK_MASK 0x0000FFFE /* work to do on interrupt/exception return */

Index: linux-2.6.21-rc7-mm2/include/asm-frv/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-frv/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-frv/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -116,7 +116,6 @@ register struct thread_info *__current_t
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#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 /* freezing for suspend */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@@ -126,7 +125,6 @@ register struct thread_info *__current_t
#define _TIF_IRET (1 << TIF_IRET)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE (1 << TIF_FREEZE)

#define _TIF_WORK_MASK 0x0000FFFE /* work to do on interrupt/exception return */
#define _TIF_ALLWORK_MASK 0x0000FFFF /* work to do on any return to u-space */
Index: linux-2.6.21-rc7-mm2/include/asm-i386/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-i386/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-i386/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -136,7 +136,6 @@ static inline struct thread_info *curren
#define TIF_MEMDIE 16
#define TIF_DEBUG 17 /* uses debug registers */
#define TIF_IO_BITMAP 18 /* uses I/O bitmap */
-#define TIF_FREEZE 19 /* is freezing for suspend */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -150,7 +149,6 @@ static inline struct thread_info *curren
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_DEBUG (1<<TIF_DEBUG)
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
-#define _TIF_FREEZE (1<<TIF_FREEZE)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
Index: linux-2.6.21-rc7-mm2/include/asm-ia64/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-ia64/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-ia64/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -89,7 +89,6 @@ struct thread_info {
#define TIF_MEMDIE 17
#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
#define TIF_DB_DISABLED 19 /* debug trap disabled for fsyscall */
-#define TIF_FREEZE 20 /* is freezing for suspend */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
@@ -101,7 +100,6 @@ struct thread_info {
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_MCA_INIT (1 << TIF_MCA_INIT)
#define _TIF_DB_DISABLED (1 << TIF_DB_DISABLED)
-#define _TIF_FREEZE (1 << TIF_FREEZE)

/* "work to do on user-return" bits */
#define TIF_ALLWORK_MASK (_TIF_NOTIFY_RESUME|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
Index: linux-2.6.21-rc7-mm2/include/asm-mips/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-mips/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-mips/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -118,7 +118,6 @@ 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)
@@ -130,7 +129,6 @@ register struct thread_info *__current_t
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE (1<<TIF_FREEZE)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK (0x0000ffef & ~_TIF_SECCOMP)
Index: linux-2.6.21-rc7-mm2/include/asm-powerpc/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-powerpc/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-powerpc/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -122,7 +122,6 @@ static inline struct thread_info *curren
#define TIF_RESTOREALL 12 /* Restore all regs (implies NOERROR) */
#define TIF_NOERROR 14 /* Force successful syscall return */
#define TIF_RESTORE_SIGMASK 15 /* Restore signal mask in do_signal */
-#define TIF_FREEZE 16 /* Freezing for suspend */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -139,7 +138,6 @@ static inline struct thread_info *curren
#define _TIF_RESTOREALL (1<<TIF_RESTOREALL)
#define _TIF_NOERROR (1<<TIF_NOERROR)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
-#define _TIF_FREEZE (1<<TIF_FREEZE)
#define _TIF_SYSCALL_T_OR_A (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)

#define _TIF_USER_WORK_MASK (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
Index: linux-2.6.21-rc7-mm2/include/asm-sh/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-sh/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-sh/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -115,7 +115,6 @@ 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_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -125,7 +124,6 @@ static inline struct thread_info *curren
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE (1<<TIF_FREEZE)

#define _TIF_WORK_MASK 0x000000FE /* work to do on interrupt/exception return */
#define _TIF_ALLWORK_MASK 0x000000FF /* work to do on any return to u-space */
Index: linux-2.6.21-rc7-mm2/include/asm-x86_64/thread_info.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/asm-x86_64/thread_info.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/asm-x86_64/thread_info.h 2007-04-27 23:23:57.000000000 +0200
@@ -122,7 +122,6 @@ static inline struct thread_info *stack_
#define TIF_MEMDIE 20
#define TIF_DEBUG 21 /* uses debug registers */
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
-#define TIF_FREEZE 23 /* is freezing for suspend */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -138,7 +137,6 @@ static inline struct thread_info *stack_
#define _TIF_ABI_PENDING (1<<TIF_ABI_PENDING)
#define _TIF_DEBUG (1<<TIF_DEBUG)
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
-#define _TIF_FREEZE (1<<TIF_FREEZE)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK \
Index: linux-2.6.21-rc7-mm2/include/linux/freezer.h
===================================================================
--- linux-2.6.21-rc7-mm2.orig/include/linux/freezer.h 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/include/linux/freezer.h 2007-04-28 00:45:13.000000000 +0200
@@ -3,12 +3,33 @@
#include <linux/sched.h>

#ifdef CONFIG_FREEZER
+
+/*
+ * Per task flags used by the freezer
+ *
+ * They should not be referred to directly outside of this file.
+ */
+#define TFF_NOFREEZE 0 /* task should not be frozen */
+#define TFF_FREEZE 8 /* task should go to the refrigerator ASAP */
+#define TFF_SKIP 9 /* do not count this task as freezable */
+#define TFF_FROZEN 10 /* task is frozen */
+
/*
* Check if a process has been frozen
*/
static inline int frozen(struct task_struct *p)
{
- return p->flags & PF_FROZEN;
+ return test_bit(TFF_FROZEN, &p->freezer_flags);
+}
+
+static inline void set_frozen_flag(struct task_struct *p)
+{
+ set_bit(TFF_FROZEN, &p->freezer_flags);
+}
+
+static inline void clear_frozen_flag(struct task_struct *p)
+{
+ clear_bit(TFF_FROZEN, &p->freezer_flags);
}

/*
@@ -16,7 +37,7 @@ static inline int frozen(struct task_str
*/
static inline int freezing(struct task_struct *p)
{
- return test_tsk_thread_flag(p, TIF_FREEZE);
+ return test_bit(TFF_FREEZE, &p->freezer_flags);
}

/*
@@ -24,15 +45,31 @@ static inline int freezing(struct task_s
*/
static inline void freeze(struct task_struct *p)
{
- set_tsk_thread_flag(p, TIF_FREEZE);
+ set_bit(TFF_FREEZE, &p->freezer_flags);
+}
+
+/*
+ * Cancel the previous 'freeze' request
+ */
+static inline void clear_freeze_flag(struct task_struct *p)
+{
+ clear_bit(TFF_FREEZE, &p->freezer_flags);
+}
+
+/*
+ * Check if the task wants to be exempted from freezing
+ */
+static inline int freezer_should_exempt(struct task_struct *p)
+{
+ return test_bit(TFF_NOFREEZE, &p->freezer_flags);
}

/*
- * Sometimes we may need to cancel the previous 'freeze' request
+ * Tell the freezer to exempt this task from freezing
*/
-static inline void do_not_freeze(struct task_struct *p)
+static inline void freezer_exempt(struct task_struct *p)
{
- clear_tsk_thread_flag(p, TIF_FREEZE);
+ set_bit(TFF_NOFREEZE, &p->freezer_flags);
}

/*
@@ -48,12 +85,12 @@ static inline int thaw_process(struct ta
{
task_lock(p);
if (frozen(p)) {
- p->flags &= ~PF_FROZEN;
+ clear_frozen_flag(p);
task_unlock(p);
wake_up_process(p);
return 1;
}
- clear_tsk_thread_flag(p, TIF_FREEZE);
+ clear_freeze_flag(p);
task_unlock(p);
return 0;
}
@@ -92,7 +129,7 @@ static inline int try_to_freeze(void)
static inline void freezer_do_not_count(void)
{
if (current->mm)
- current->flags |= PF_FREEZER_SKIP;
+ set_bit(TFF_SKIP, &current->freezer_flags);
}

/*
@@ -102,7 +139,7 @@ static inline void freezer_do_not_count(
static inline void freezer_count(void)
{
if (current->mm) {
- current->flags &= ~PF_FREEZER_SKIP;
+ clear_bit(TFF_SKIP, &current->freezer_flags);
try_to_freeze();
}
}
@@ -112,13 +149,17 @@ static inline void freezer_count(void)
*/
static inline int freezer_should_skip(struct task_struct *p)
{
- return !!(p->flags & PF_FREEZER_SKIP);
+ return test_bit(TFF_SKIP, &current->freezer_flags);
}

#else
static inline int frozen(struct task_struct *p) { return 0; }
+static inline void set_frozen_flag(struct task_struct *p) {}
+static inline void clear_frozen_flag(struct task_struct *p) {}
static inline int freezing(struct task_struct *p) { return 0; }
static inline void freeze(struct task_struct *p) { BUG(); }
+static inline int freezer_should_exempt(struct task_struct *p) { return 0; }
+static inline void freezer_exempt(struct task_struct *p) {}
static inline int thaw_process(struct task_struct *p) { return 1; }

static inline void refrigerator(void) {}
Index: linux-2.6.21-rc7-mm2/kernel/sched.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/sched.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/sched.c 2007-04-27 23:23:57.000000000 +0200
@@ -5478,7 +5478,7 @@ migration_call(struct notifier_block *nf
p = kthread_create(migration_thread, hcpu, "migration/%d",cpu);
if (IS_ERR(p))
return NOTIFY_BAD;
- p->flags |= PF_NOFREEZE;
+ freezer_exempt(p);
kthread_bind(p, cpu);
/* Must be high prio: stop_machine expects to yield to it. */
rq = task_rq_lock(p, &flags);
Index: linux-2.6.21-rc7-mm2/arch/i386/kernel/apm.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/arch/i386/kernel/apm.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/arch/i386/kernel/apm.c 2007-04-27 23:23:57.000000000 +0200
@@ -2313,7 +2313,7 @@ static int __init apm_init(void)
remove_proc_entry("apm", NULL);
return err;
}
- kapmd_task->flags |= PF_NOFREEZE;
+ freezer_exempt(kapmd_task);
wake_up_process(kapmd_task);

if (num_online_cpus() > 1 && !smp ) {
Index: linux-2.6.21-rc7-mm2/drivers/block/loop.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/block/loop.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/block/loop.c 2007-04-27 23:23:57.000000000 +0200
@@ -582,7 +582,7 @@ static int loop_thread(void *data)
* hence, it mustn't be stopped at all
* because it could be indirectly used during suspension
*/
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

set_user_nice(current, -20);

Index: linux-2.6.21-rc7-mm2/drivers/char/apm-emulation.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/char/apm-emulation.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/char/apm-emulation.c 2007-04-27 23:23:57.000000000 +0200
@@ -336,7 +336,7 @@ apm_ioctl(struct inode * inode, struct f
* threads.
*/
flags = current->flags;
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

wait_event(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
@@ -372,7 +372,7 @@ apm_ioctl(struct inode * inode, struct f
* threads.
*/
flags = current->flags;
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

wait_event_interruptible(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
@@ -601,7 +601,7 @@ static int __init apm_init(void)
kapmd_tsk = NULL;
return ret;
}
- kapmd_tsk->flags |= PF_NOFREEZE;
+ freezer_exempt(kapmd_tsk);
wake_up_process(kapmd_tsk);

#ifdef CONFIG_PROC_FS
Index: linux-2.6.21-rc7-mm2/drivers/ieee1394/ieee1394_core.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/ieee1394/ieee1394_core.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/ieee1394/ieee1394_core.c 2007-04-27 23:23:57.000000000 +0200
@@ -1134,7 +1134,7 @@ static int hpsbpkt_thread(void *__hi)
struct list_head tmp;
int may_schedule;

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

while (!kthread_should_stop()) {

Index: linux-2.6.21-rc7-mm2/drivers/md/md.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/md/md.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/md/md.c 2007-04-27 23:23:57.000000000 +0200
@@ -4541,7 +4541,7 @@ static int md_thread(void * arg)
* many dirty RAID5 blocks.
*/

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);
while (!kthread_should_stop()) {

/* We need to wait INTERRUPTIBLE so that
Index: linux-2.6.21-rc7-mm2/drivers/mmc/card/queue.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/mmc/card/queue.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/mmc/card/queue.c 2007-04-27 23:23:57.000000000 +0200
@@ -66,7 +66,8 @@ static int mmc_queue_thread(void *d)
* 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;
+ freezer_exempt(current);

down(&mq->thread_sem);
do {
Index: linux-2.6.21-rc7-mm2/drivers/mtd/mtd_blkdevs.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/mtd/mtd_blkdevs.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/mtd/mtd_blkdevs.c 2007-04-27 23:23:57.000000000 +0200
@@ -81,7 +81,8 @@ 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;
+ freezer_exempt(current);

spin_lock_irq(rq->queue_lock);
while (!kthread_should_stop()) {
Index: linux-2.6.21-rc7-mm2/drivers/scsi/libsas/sas_scsi_host.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/scsi/libsas/sas_scsi_host.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/scsi/libsas/sas_scsi_host.c 2007-04-27 23:23:57.000000000 +0200
@@ -871,7 +871,7 @@ static int sas_queue_thread(void *_sas_h
struct sas_ha_struct *sas_ha = _sas_ha;
struct scsi_core *core = &sas_ha->core;

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

complete(&queue_th_comp);

Index: linux-2.6.21-rc7-mm2/drivers/scsi/scsi_error.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/scsi/scsi_error.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/scsi/scsi_error.c 2007-04-27 23:23:57.000000000 +0200
@@ -1536,7 +1536,7 @@ int scsi_error_handler(void *data)
{
struct Scsi_Host *shost = data;

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

/*
* We use TASK_INTERRUPTIBLE so that the thread is not
Index: linux-2.6.21-rc7-mm2/drivers/usb/storage/usb.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/drivers/usb/storage/usb.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/drivers/usb/storage/usb.c 2007-04-27 23:23:57.000000000 +0200
@@ -301,7 +301,7 @@ static int usb_stor_control_thread(void
struct us_data *us = (struct us_data *)__us;
struct Scsi_Host *host = us_to_host(us);

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

for(;;) {
try_to_freeze();
Index: linux-2.6.21-rc7-mm2/kernel/fork.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/fork.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/fork.c 2007-04-27 23:23:57.000000000 +0200
@@ -921,11 +921,14 @@ static inline void copy_flags(unsigned l
{
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;
p->flags = new_flags;
+#ifdef CONFIG_FREEZER
+ p->freezer_flags = 0;
+#endif
}

asmlinkage long sys_set_tid_address(int __user *tidptr)
Index: linux-2.6.21-rc7-mm2/kernel/rcutorture.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/rcutorture.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/rcutorture.c 2007-04-27 23:23:57.000000000 +0200
@@ -559,7 +559,7 @@ rcu_torture_fakewriter(void *arg)

VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
set_user_nice(current, 19);
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

do {
schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
@@ -590,7 +590,7 @@ rcu_torture_reader(void *arg)

VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
set_user_nice(current, 19);
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

do {
idx = cur_ops->readlock();
Index: linux-2.6.21-rc7-mm2/kernel/softirq.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/softirq.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/softirq.c 2007-04-27 23:23:57.000000000 +0200
@@ -490,7 +490,7 @@ void __init softirq_init(void)
static int ksoftirqd(void * __bind_cpu)
{
set_user_nice(current, 15);
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

set_current_state(TASK_INTERRUPTIBLE);

Index: linux-2.6.21-rc7-mm2/kernel/softlockup.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/softlockup.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/softlockup.c 2007-04-27 23:23:57.000000000 +0200
@@ -117,7 +117,7 @@ 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;
+ freezer_exempt(current);

/* initialize timestamp */
touch_softlockup_watchdog();
Index: linux-2.6.21-rc7-mm2/kernel/workqueue.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/workqueue.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/workqueue.c 2007-04-27 23:23:57.000000000 +0200
@@ -291,7 +291,7 @@ static int worker_thread(void *__cwq)
DEFINE_WAIT(wait);

if (!cwq->wq->freezeable)
- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

for (;;) {
prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE);
Index: linux-2.6.21-rc7-mm2/kernel/freezer.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/freezer.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/freezer.c 2007-04-27 23:54:02.000000000 +0200
@@ -26,7 +26,7 @@
static inline int freezeable(struct task_struct * p)
{
if ((p == current) ||
- (p->flags & PF_NOFREEZE) ||
+ freezer_should_exempt(p) ||
(p->exit_state != 0))
return 0;
return 1;
@@ -37,11 +37,11 @@ static inline int freezeable(struct task
*/
static inline void frozen_process(void)
{
- if (!unlikely(current->flags & PF_NOFREEZE)) {
- current->flags |= PF_FROZEN;
+ if (!unlikely(freezer_should_exempt(current))) {
+ set_frozen_flag(current);
wmb();
}
- clear_tsk_thread_flag(current, TIF_FREEZE);
+ clear_freeze_flag(current);
}

/* Refrigerator is place where frozen processes are stored :-). */
@@ -100,7 +100,7 @@ static void cancel_freezing(struct task_

if (freezing(p)) {
pr_debug(" clean up: %s\n", p->comm);
- do_not_freeze(p);
+ clear_freeze_flag(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
recalc_sigpending_tsk(p);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
Index: linux-2.6.21-rc7-mm2/Documentation/power/kernel_threads.txt
===================================================================
--- linux-2.6.21-rc7-mm2.orig/Documentation/power/kernel_threads.txt 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/Documentation/power/kernel_threads.txt 2007-04-27 23:23:57.000000000 +0200
@@ -32,7 +32,7 @@ like this:
*/
daemonize("usb-storage");

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

from drivers/usb/storage/usb.c::usb_stor_control_thread()

Index: linux-2.6.21-rc7-mm2/Documentation/power/swsusp.txt
===================================================================
--- linux-2.6.21-rc7-mm2.orig/Documentation/power/swsusp.txt 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/Documentation/power/swsusp.txt 2007-04-27 23:23:57.000000000 +0200
@@ -152,8 +152,8 @@ 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).
+instead use freezer_exempt() to mark the thread as nonfreezable when creating
+it (and be very careful).


Q: What is the difference between "platform" and "shutdown"?
Index: linux-2.6.21-rc7-mm2/kernel/kthread.c
===================================================================
--- linux-2.6.21-rc7-mm2.orig/kernel/kthread.c 2007-04-27 23:20:23.000000000 +0200
+++ linux-2.6.21-rc7-mm2/kernel/kthread.c 2007-04-27 23:23:57.000000000 +0200
@@ -13,6 +13,7 @@
#include <linux/file.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/freezer.h>
#include <asm/semaphore.h>

static DEFINE_SPINLOCK(kthread_create_lock);
@@ -232,7 +233,7 @@ int kthreadd(void *unused)
/* Setup a clean context for our children to inherit. */
kthreadd_setup();

- current->flags |= PF_NOFREEZE;
+ freezer_exempt(current);

for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
-
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