Merge branch 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into pm-freezer

* 'pm-freezer' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc: (24 commits)
  freezer: fix wait_event_freezable/__thaw_task races
  freezer: kill unused set_freezable_with_signal()
  dmatest: don't use set_freezable_with_signal()
  usb_storage: don't use set_freezable_with_signal()
  freezer: remove unused @sig_only from freeze_task()
  freezer: use lock_task_sighand() in fake_signal_wake_up()
  freezer: restructure __refrigerator()
  freezer: fix set_freezable[_with_signal]() race
  freezer: remove should_send_signal() and update frozen()
  freezer: remove now unused TIF_FREEZE
  freezer: make freezing() test freeze conditions in effect instead of TIF_FREEZE
  cgroup_freezer: prepare for removal of TIF_FREEZE
  freezer: clean up freeze_processes() failure path
  freezer: kill PF_FREEZING
  freezer: test freezable conditions while holding freezer_lock
  freezer: make freezing indicate freeze condition in effect
  freezer: use dedicated lock instead of task_lock() + memory barrier
  freezer: don't distinguish nosig tasks on thaw
  freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
  freezer: rename thaw_process() to __thaw_task() and simplify the implementation
  ...

Documentation/power/freezing-of-tasks.txt

@@ -21,7 +21,7 @@ freeze_processes() (defined in kernel/power/process.c) is called.  It executes
 try_to_freeze_tasks() that sets TIF_FREEZE for all of the freezable tasks and
 either wakes them up, if they are kernel threads, or sends fake signals to them,
 if they are user space processes.  A task that has TIF_FREEZE set, should react
-to it by calling the function called refrigerator() (defined in
+to it by calling the function called __refrigerator() (defined in
 kernel/freezer.c), which sets the task's PF_FROZEN flag, changes its state
 to TASK_UNINTERRUPTIBLE and makes it loop until PF_FROZEN is cleared for it.
 Then, we say that the task is 'frozen' and therefore the set of functions
@@ -29,10 +29,10 @@ handling this mechanism is referred to as 'the freezer' (these functions are
 defined in kernel/power/process.c, kernel/freezer.c & include/linux/freezer.h).
 User space processes are generally frozen before kernel threads.
 
-It is not recommended to call refrigerator() directly.  Instead, it is
-recommended to use the try_to_freeze() function (defined in
-include/linux/freezer.h), that checks the task's TIF_FREEZE flag and makes the
-task enter refrigerator() if the flag is set.
+__refrigerator() must not be called directly.  Instead, use the
+try_to_freeze() function (defined in include/linux/freezer.h), that checks
+the task's TIF_FREEZE flag and makes the task enter __refrigerator() if the
+flag is set.
 
 For user space processes try_to_freeze() is called automatically from the
 signal-handling code, but the freezable kernel threads need to call it
@@ -61,13 +61,13 @@ wait_event_freezable() and wait_event_freezable_timeout() macros.
 After the system memory state has been restored from a hibernation image and
 devices have been reinitialized, the function thaw_processes() is called in
 order to clear the PF_FROZEN flag for each frozen task.  Then, the tasks that
-have been frozen leave refrigerator() and continue running.
+have been frozen leave __refrigerator() and continue running.
 
 III. Which kernel threads are freezable?
 
 Kernel threads are not freezable by default.  However, a kernel thread may clear
 PF_NOFREEZE for itself by calling set_freezable() (the resetting of PF_NOFREEZE
-directly is strongly discouraged).  From this point it is regarded as freezable
+directly is not allowed).  From this point it is regarded as freezable
 and must call try_to_freeze() in a suitable place.
 
 IV. Why do we do that?

arch/alpha/include/asm/thread_info.h

@@ -79,7 +79,6 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define TIF_UAC_SIGBUS		12	/* ! userspace part of 'osf_sysinfo' */
 #define TIF_MEMDIE		13	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	14	/* restore signal mask in do_signal */
-#define TIF_FREEZE		16	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
@@ -87,7 +86,6 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_RESTORE_SIGMASK	(1<<TIF_RESTORE_SIGMASK)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 /* Work to do on interrupt/exception return.  */
 #define _TIF_WORK_MASK		(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \

arch/arm/include/asm/thread_info.h

@@ -142,7 +142,6 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #define TIF_POLLING_NRFLAG	16
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
-#define TIF_FREEZE		19
 #define TIF_RESTORE_SIGMASK	20
 #define TIF_SECCOMP		21
 
@@ -152,7 +151,6 @@ extern void vfp_flush_hwstate(struct thread_info *);
 #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)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 

arch/avr32/include/asm/thread_info.h

@@ -85,7 +85,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTORE_SIGMASK	7	/* restore signal mask in do_signal */
 #define TIF_CPU_GOING_TO_SLEEP	8	/* CPU is entering sleep 0 mode */
 #define TIF_NOTIFY_RESUME	9	/* callback before returning to user */
-#define TIF_FREEZE		29
 #define TIF_DEBUG		30	/* debugging enabled */
 #define TIF_USERSPACE		31      /* true if FS sets userspace */
 
@@ -98,7 +97,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 
 /* Note: The masks below must never span more than 16 bits! */
 

arch/blackfin/include/asm/thread_info.h

@@ -100,7 +100,6 @@ static inline struct thread_info *current_thread_info(void)
 					   TIF_NEED_RESCHED */
 #define TIF_MEMDIE		4	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	5	/* restore signal mask in do_signal() */
-#define TIF_FREEZE		6	/* is freezing for suspend */
 #define TIF_IRQ_SYNC		7	/* sync pipeline stage */
 #define TIF_NOTIFY_RESUME	8	/* callback before returning to user */
 #define TIF_SINGLESTEP		9
@@ -111,7 +110,6 @@ static inline struct thread_info *current_thread_info(void)
 #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_IRQ_SYNC		(1<<TIF_IRQ_SYNC)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)

arch/cris/include/asm/thread_info.h

@@ -86,7 +86,6 @@ struct thread_info {
 #define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal() */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17	/* is terminating due to OOM killer */
-#define TIF_FREEZE		18	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
@@ -94,7 +93,6 @@ struct thread_info {
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #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 */

arch/frv/include/asm/thread_info.h

@@ -111,7 +111,6 @@ register struct thread_info *__current_thread_info asm("gr15");
 #define TIF_RESTORE_SIGMASK	5	/* restore signal mask in do_signal() */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17	/* is terminating due to OOM killer */
-#define TIF_FREEZE		18	/* freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
@@ -120,7 +119,6 @@ register struct thread_info *__current_thread_info asm("gr15");
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #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 */

arch/h8300/include/asm/thread_info.h

@@ -90,7 +90,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE		4	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	5	/* restore signal mask in do_signal() */
 #define TIF_NOTIFY_RESUME	6	/* callback before returning to user */
-#define TIF_FREEZE		16	/* is freezing for suspend */
 
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
@@ -99,7 +98,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_RESTORE_SIGMASK	(1<<TIF_RESTORE_SIGMASK)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 #define _TIF_WORK_MASK		0x0000FFFE	/* work to do on interrupt/exception return */
 

arch/ia64/include/asm/thread_info.h

@@ -113,7 +113,6 @@ struct thread_info {
 #define TIF_MEMDIE		17	/* is terminating due to OOM killer */
 #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_RESTORE_RSE		21	/* user RBS is newer than kernel RBS */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
@@ -126,7 +125,6 @@ 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)
 #define _TIF_RESTORE_RSE	(1 << TIF_RESTORE_RSE)
 
 /* "work to do on user-return" bits */

arch/m32r/include/asm/thread_info.h

@@ -138,7 +138,6 @@ static inline unsigned int get_thread_fault_code(void)
 #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	/* is terminating due to OOM killer */
-#define TIF_FREEZE		19	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
@@ -149,7 +148,6 @@ static inline unsigned int get_thread_fault_code(void)
 #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)
 
 #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 */

arch/m68k/include/asm/thread_info.h

@@ -103,7 +103,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_DELAYED_TRACE	14	/* single step a syscall */
 #define TIF_SYSCALL_TRACE	15	/* syscall trace active */
 #define TIF_MEMDIE		16	/* is terminating due to OOM killer */
-#define TIF_FREEZE		17	/* thread is freezing for suspend */
 #define TIF_RESTORE_SIGMASK	18	/* restore signal mask in do_signal */
 
 #endif	/* _ASM_M68K_THREAD_INFO_H */

arch/microblaze/include/asm/thread_info.h

@@ -125,7 +125,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE		6	/* is terminating due to OOM killer */
 #define TIF_SYSCALL_AUDIT	9       /* syscall auditing active */
 #define TIF_SECCOMP		10      /* secure computing */
-#define TIF_FREEZE		14	/* Freezing for suspend */
 
 /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_POLLING_NRFLAG	16
@@ -137,7 +136,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_IRET		(1 << TIF_IRET)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 

arch/mips/include/asm/thread_info.h

@@ -117,7 +117,6 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #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	/* is terminating due to OOM killer */
-#define TIF_FREEZE		19
 #define TIF_FIXADE		20	/* Fix address errors in software */
 #define TIF_LOGADE		21	/* Log address errors to syslog */
 #define TIF_32BIT_REGS		22	/* also implies 16/32 fprs */
@@ -141,7 +140,6 @@ register struct thread_info *__current_thread_info __asm__("$28");
 #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)
 #define _TIF_FIXADE		(1<<TIF_FIXADE)
 #define _TIF_LOGADE		(1<<TIF_LOGADE)
 #define _TIF_32BIT_REGS		(1<<TIF_32BIT_REGS)

arch/mn10300/include/asm/thread_info.h

@@ -165,7 +165,6 @@ extern void free_thread_info(struct thread_info *);
 #define TIF_RESTORE_SIGMASK	5	/* restore signal mask in do_signal() */
 #define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		17	/* is terminating due to OOM killer */
-#define TIF_FREEZE		18	/* freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	+(1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	+(1 << TIF_NOTIFY_RESUME)
@@ -174,7 +173,6 @@ extern void free_thread_info(struct thread_info *);
 #define _TIF_SINGLESTEP		+(1 << TIF_SINGLESTEP)
 #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 */

arch/parisc/include/asm/thread_info.h

@@ -58,7 +58,6 @@ struct thread_info {
 #define TIF_32BIT               4       /* 32 bit binary */
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	6	/* restore saved signal mask */
-#define TIF_FREEZE		7	/* is freezing for suspend */
 #define TIF_NOTIFY_RESUME	8	/* callback before returning to user */
 #define TIF_SINGLESTEP		9	/* single stepping? */
 #define TIF_BLOCKSTEP		10	/* branch stepping? */
@@ -69,7 +68,6 @@ struct thread_info {
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)

arch/powerpc/include/asm/thread_info.h

@@ -109,7 +109,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTOREALL		11	/* Restore all regs (implies NOERROR) */
 #define TIF_NOERROR		12	/* Force successful syscall return */
 #define TIF_NOTIFY_RESUME	13	/* callback before returning to user */
-#define TIF_FREEZE		14	/* Freezing for suspend */
 #define TIF_SYSCALL_TRACEPOINT	15	/* syscall tracepoint instrumentation */
 #define TIF_RUNLATCH		16	/* Is the runlatch enabled? */
 
@@ -127,7 +126,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_RESTOREALL		(1<<TIF_RESTOREALL)
 #define _TIF_NOERROR		(1<<TIF_NOERROR)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
 #define _TIF_RUNLATCH		(1<<TIF_RUNLATCH)
 #define _TIF_SYSCALL_T_OR_A	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \

arch/s390/include/asm/thread_info.h

@@ -102,7 +102,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_RESTORE_SIGMASK	19	/* restore signal mask in do_signal() */
 #define TIF_SINGLE_STEP		20	/* This task is single stepped */
-#define TIF_FREEZE		21	/* thread is freezing for suspend */
 
 #define _TIF_SYSCALL		(1<<TIF_SYSCALL)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
@@ -119,7 +118,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_31BIT		(1<<TIF_31BIT)
 #define _TIF_SINGLE_STEP	(1<<TIF_SINGLE_STEP)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 #ifdef CONFIG_64BIT
 #define is_32bit_task()		(test_thread_flag(TIF_31BIT))

arch/sh/include/asm/thread_info.h

@@ -122,7 +122,6 @@ extern void init_thread_xstate(void);
 #define TIF_SYSCALL_TRACEPOINT	8	/* for ftrace syscall instrumentation */
 #define TIF_POLLING_NRFLAG	17	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
-#define TIF_FREEZE		19	/* Freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -133,7 +132,6 @@ extern void init_thread_xstate(void);
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 
 /*
  * _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or we

arch/sparc/include/asm/thread_info_32.h

@@ -133,7 +133,6 @@ BTFIXUPDEF_CALL(void, free_thread_info, struct thread_info *)
 #define TIF_POLLING_NRFLAG	9	/* true if poll_idle() is polling
 					 * TIF_NEED_RESCHED */
 #define TIF_MEMDIE		10	/* is terminating due to OOM killer */
-#define TIF_FREEZE		11	/* is freezing for suspend */
 
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
@@ -147,7 +146,6 @@ BTFIXUPDEF_CALL(void, free_thread_info, struct thread_info *)
 #define _TIF_DO_NOTIFY_RESUME_MASK	(_TIF_NOTIFY_RESUME | \
 					 _TIF_SIGPENDING | \
 					 _TIF_RESTORE_SIGMASK)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 #endif /* __KERNEL__ */
 

arch/sparc/include/asm/thread_info_64.h

@@ -225,7 +225,6 @@ register struct thread_info *current_thread_info_reg asm("g6");
 /* flag bit 12 is available */
 #define TIF_MEMDIE		13	/* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG	14
-#define TIF_FREEZE		15	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
@@ -237,7 +236,6 @@ register struct thread_info *current_thread_info_reg asm("g6");
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
-#define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 #define _TIF_USER_WORK_MASK	((0xff << TI_FLAG_WSAVED_SHIFT) | \
 				 _TIF_DO_NOTIFY_RESUME_MASK | \

arch/um/include/asm/thread_info.h

@@ -71,7 +71,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
 #define TIF_SYSCALL_AUDIT	6
 #define TIF_RESTORE_SIGMASK	7
-#define TIF_FREEZE		16	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -80,6 +79,5 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 
 #endif

arch/unicore32/include/asm/thread_info.h

@@ -135,14 +135,12 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_SYSCALL_TRACE	8
 #define TIF_MEMDIE		18
-#define TIF_FREEZE		19
 #define TIF_RESTORE_SIGMASK	20
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 
 /*

arch/x86/include/asm/thread_info.h

@@ -90,7 +90,6 @@ struct thread_info {
 #define TIF_MEMDIE		20	/* is terminating due to OOM killer */
 #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_FORCED_TF		24	/* true if TF in eflags artificially */
 #define TIF_BLOCKSTEP		25	/* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES	27	/* task is updating the mmu lazily */
@@ -112,7 +111,6 @@ struct thread_info {
 #define _TIF_FORK		(1 << TIF_FORK)
 #define _TIF_DEBUG		(1 << TIF_DEBUG)
 #define _TIF_IO_BITMAP		(1 << TIF_IO_BITMAP)
-#define _TIF_FREEZE		(1 << TIF_FREEZE)
 #define _TIF_FORCED_TF		(1 << TIF_FORCED_TF)
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES	(1 << TIF_LAZY_MMU_UPDATES)

arch/xtensa/include/asm/thread_info.h

@@ -132,7 +132,6 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE		5	/* is terminating due to OOM killer */
 #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_FREEZE		17	/* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
@@ -141,7 +140,6 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_IRET		(1<<TIF_IRET)
 #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 */
 #define _TIF_ALLWORK_MASK	0x0000FFFF	/* work to do on any return to u-space */

drivers/bluetooth/btmrvl_main.c

@@ -475,8 +475,6 @@ static int btmrvl_service_main_thread(void *data)
 
 	init_waitqueue_entry(&wait, current);
 
-	current->flags |= PF_NOFREEZE;
-
 	for (;;) {
 		add_wait_queue(&thread->wait_q, &wait);
 

drivers/dma/dmatest.c

@@ -214,9 +214,18 @@ static unsigned int dmatest_verify(u8 **bufs, unsigned int start,
 	return error_count;
 }
 
-static void dmatest_callback(void *completion)
+/* poor man's completion - we want to use wait_event_freezable() on it */
+struct dmatest_done {
+	bool			done;
+	wait_queue_head_t	*wait;
+};
+
+static void dmatest_callback(void *arg)
 {
-	complete(completion);
+	struct dmatest_done *done = arg;
+
+	done->done = true;
+	wake_up_all(done->wait);
 }
 
 /*
@@ -235,7 +244,9 @@ static void dmatest_callback(void *completion)
  */
 static int dmatest_func(void *data)
 {
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(done_wait);
 	struct dmatest_thread	*thread = data;
+	struct dmatest_done	done = { .wait = &done_wait };
 	struct dma_chan		*chan;
 	const char		*thread_name;
 	unsigned int		src_off, dst_off, len;
@@ -252,7 +263,7 @@ static int dmatest_func(void *data)
 	int			i;
 
 	thread_name = current->comm;
-	set_freezable_with_signal();
+	set_freezable();
 
 	ret = -ENOMEM;
 
@@ -306,9 +317,6 @@ static int dmatest_func(void *data)
 		struct dma_async_tx_descriptor *tx = NULL;
 		dma_addr_t dma_srcs[src_cnt];
 		dma_addr_t dma_dsts[dst_cnt];
-		struct completion cmp;
-		unsigned long start, tmo, end = 0 /* compiler... */;
-		bool reload = true;
 		u8 align = 0;
 
 		total_tests++;
@@ -391,9 +399,9 @@ static int dmatest_func(void *data)
 			continue;
 		}
 
-		init_completion(&cmp);
+		done.done = false;
 		tx->callback = dmatest_callback;
-		tx->callback_param = &cmp;
+		tx->callback_param = &done;
 		cookie = tx->tx_submit(tx);
 
 		if (dma_submit_error(cookie)) {
@@ -407,20 +415,20 @@ static int dmatest_func(void *data)
 		}
 		dma_async_issue_pending(chan);
 
-		do {
-			start = jiffies;
-			if (reload)
-				end = start + msecs_to_jiffies(timeout);
-			else if (end <= start)
-				end = start + 1;
-			tmo = wait_for_completion_interruptible_timeout(&cmp,
-								end - start);
-			reload = try_to_freeze();
-		} while (tmo == -ERESTARTSYS);
+		wait_event_freezable_timeout(done_wait, done.done,
+					     msecs_to_jiffies(timeout));
 
 		status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
 
-		if (tmo == 0) {
+		if (!done.done) {
+			/*
+			 * We're leaving the timed out dma operation with
+			 * dangling pointer to done_wait.  To make this
+			 * correct, we'll need to allocate wait_done for
+			 * each test iteration and perform "who's gonna
+			 * free it this time?" dancing.  For now, just
+			 * leave it dangling.
+			 */
 			pr_warning("%s: #%u: test timed out\n",
 				   thread_name, total_tests - 1);
 			failed_tests++;

drivers/mfd/twl6030-irq.c

@@ -138,8 +138,6 @@ static int twl6030_irq_thread(void *data)
 	static const unsigned max_i2c_errors = 100;
 	int ret;
 
-	current->flags |= PF_NOFREEZE;
-
 	while (!kthread_should_stop()) {
 		int i;
 		union {

drivers/net/irda/stir4200.c

@@ -750,7 +750,7 @@ static int stir_transmit_thread(void *arg)
 
 			write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);
 
-			refrigerator();
+			try_to_freeze();
 
 			if (change_speed(stir, stir->speed))
 				break;

drivers/platform/x86/thinkpad_acpi.c

@@ -2456,8 +2456,9 @@ static int hotkey_kthread(void *data)
 	u32 poll_mask, event_mask;
 	unsigned int si, so;
 	unsigned long t;
-	unsigned int change_detector, must_reset;
+	unsigned int change_detector;
 	unsigned int poll_freq;
+	bool was_frozen;
 
 	mutex_lock(&hotkey_thread_mutex);
 
@@ -2488,14 +2489,14 @@ static int hotkey_kthread(void *data)
 				t = 100;	/* should never happen... */
 		}
 		t = msleep_interruptible(t);
-		if (unlikely(kthread_should_stop()))
+		if (unlikely(kthread_freezable_should_stop(&was_frozen)))
 			break;
-		must_reset = try_to_freeze();
-		if (t > 0 && !must_reset)
+
+		if (t > 0 && !was_frozen)
 			continue;
 
 		mutex_lock(&hotkey_thread_data_mutex);
-		if (must_reset || hotkey_config_change != change_detector) {
+		if (was_frozen || hotkey_config_change != change_detector) {
 			/* forget old state on thaw or config change */
 			si = so;
 			t = 0;
@@ -2528,10 +2529,6 @@ exit:
 static void hotkey_poll_stop_sync(void)
 {
 	if (tpacpi_hotkey_task) {
-		if (frozen(tpacpi_hotkey_task) ||
-		    freezing(tpacpi_hotkey_task))
-			thaw_process(tpacpi_hotkey_task);
-
 		kthread_stop(tpacpi_hotkey_task);
 		tpacpi_hotkey_task = NULL;
 		mutex_lock(&hotkey_thread_mutex);

drivers/staging/rts_pstor/rtsx.c

@@ -466,8 +466,6 @@ static int rtsx_control_thread(void *__dev)
 	struct rtsx_chip *chip = dev->chip;
 	struct Scsi_Host *host = rtsx_to_host(dev);
 
-	current->flags |= PF_NOFREEZE;
-
 	for (;;) {
 		if (wait_for_completion_interruptible(&dev->cmnd_ready))
 			break;

drivers/usb/storage/usb.c

@@ -831,7 +831,8 @@ static int usb_stor_scan_thread(void * __us)
 
 	dev_dbg(dev, "device found\n");
 
-	set_freezable_with_signal();
+	set_freezable();
+
 	/*
 	 * Wait for the timeout to expire or for a disconnect
 	 *
@@ -839,16 +840,16 @@ static int usb_stor_scan_thread(void * __us)
 	 * fail to freeze, but we can't be non-freezable either. Nor can
 	 * khubd freeze while waiting for scanning to complete as it may
 	 * hold the device lock, causing a hang when suspending devices.
-	 * So we request a fake signal when freezing and use
-	 * interruptible sleep to kick us out of our wait early when
-	 * freezing happens.
+	 * So instead of using wait_event_freezable(), explicitly test
+	 * for (DONT_SCAN || freezing) in interruptible wait and proceed
+	 * if any of DONT_SCAN, freezing or timeout has happened.
 	 */
 	if (delay_use > 0) {
 		dev_dbg(dev, "waiting for device to settle "
 				"before scanning\n");
 		wait_event_interruptible_timeout(us->delay_wait,
-				test_bit(US_FLIDX_DONT_SCAN, &us->dflags),
-				delay_use * HZ);
+				test_bit(US_FLIDX_DONT_SCAN, &us->dflags) ||
+				freezing(current), delay_use * HZ);
 	}
 
 	/* If the device is still connected, perform the scanning */

fs/btrfs/async-thread.c

@@ -340,7 +340,7 @@ again:
 		if (freezing(current)) {
 			worker->working = 0;
 			spin_unlock_irq(&worker->lock);
-			refrigerator();
+			try_to_freeze();
 		} else {
 			spin_unlock_irq(&worker->lock);
 			if (!kthread_should_stop()) {

fs/btrfs/disk-io.c

@@ -1579,9 +1579,7 @@ static int cleaner_kthread(void *arg)
 			btrfs_run_defrag_inodes(root->fs_info);
 		}
 
-		if (freezing(current)) {
-			refrigerator();
-		} else {
+		if (!try_to_freeze()) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (!kthread_should_stop())
 				schedule();
@@ -1635,9 +1633,7 @@ sleep:
 		wake_up_process(root->fs_info->cleaner_kthread);
 		mutex_unlock(&root->fs_info->transaction_kthread_mutex);
 
-		if (freezing(current)) {
-			refrigerator();
-		} else {
+		if (!try_to_freeze()) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (!kthread_should_stop() &&
 			    !btrfs_transaction_blocked(root->fs_info))

fs/ext4/super.c

@@ -2884,8 +2884,7 @@ cont_thread:
 		}
 		mutex_unlock(&eli->li_list_mtx);
 
-		if (freezing(current))
-			refrigerator();
+		try_to_freeze();
 
 		cur = jiffies;
 		if ((time_after_eq(cur, next_wakeup)) ||

fs/fs-writeback.c

@@ -947,7 +947,7 @@ int bdi_writeback_thread(void *data)
 
 	trace_writeback_thread_start(bdi);
 
-	while (!kthread_should_stop()) {
+	while (!kthread_freezable_should_stop(NULL)) {
 		/*
 		 * Remove own delayed wake-up timer, since we are already awake
 		 * and we'll take care of the preriodic write-back.
@@ -977,8 +977,6 @@ int bdi_writeback_thread(void *data)
 			 */
 			schedule();
 		}
-
-		try_to_freeze();
 	}
 
 	/* Flush any work that raced with us exiting */

fs/gfs2/log.c

@@ -951,8 +951,8 @@ int gfs2_logd(void *data)
 			wake_up(&sdp->sd_log_waitq);
 
 		t = gfs2_tune_get(sdp, gt_logd_secs) * HZ;
-		if (freezing(current))
-			refrigerator();
+
+		try_to_freeze();
 
 		do {
 			prepare_to_wait(&sdp->sd_logd_waitq, &wait,

fs/gfs2/quota.c

@@ -1427,8 +1427,8 @@ int gfs2_quotad(void *data)
 		/* Check for & recover partially truncated inodes */
 		quotad_check_trunc_list(sdp);
 
-		if (freezing(current))
-			refrigerator();
+		try_to_freeze();
+
 		t = min(quotad_timeo, statfs_timeo);
 
 		prepare_to_wait(&sdp->sd_quota_wait, &wait, TASK_INTERRUPTIBLE);

fs/jbd/journal.c

@@ -166,7 +166,7 @@ loop:
 		 */
 		jbd_debug(1, "Now suspending kjournald\n");
 		spin_unlock(&journal->j_state_lock);
-		refrigerator();
+		try_to_freeze();
 		spin_lock(&journal->j_state_lock);
 	} else {
 		/*

fs/jbd2/journal.c

@@ -173,7 +173,7 @@ loop:
 		 */
 		jbd_debug(1, "Now suspending kjournald2\n");
 		write_unlock(&journal->j_state_lock);
-		refrigerator();
+		try_to_freeze();
 		write_lock(&journal->j_state_lock);
 	} else {
 		/*

fs/jfs/jfs_logmgr.c

@@ -2349,7 +2349,7 @@ int jfsIOWait(void *arg)
 
 		if (freezing(current)) {
 			spin_unlock_irq(&log_redrive_lock);
-			refrigerator();
+			try_to_freeze();
 		} else {
 			set_current_state(TASK_INTERRUPTIBLE);
 			spin_unlock_irq(&log_redrive_lock);

fs/jfs/jfs_txnmgr.c

@@ -2800,7 +2800,7 @@ int jfs_lazycommit(void *arg)
 
 		if (freezing(current)) {
 			LAZY_UNLOCK(flags);
-			refrigerator();
+			try_to_freeze();
 		} else {
 			DECLARE_WAITQUEUE(wq, current);
 
@@ -2994,7 +2994,7 @@ int jfs_sync(void *arg)
 
 		if (freezing(current)) {
 			TXN_UNLOCK();
-			refrigerator();
+			try_to_freeze();
 		} else {
 			set_current_state(TASK_INTERRUPTIBLE);
 			TXN_UNLOCK();

fs/nilfs2/segment.c

@@ -2470,7 +2470,7 @@ static int nilfs_segctor_thread(void *arg)
 
 	if (freezing(current)) {
 		spin_unlock(&sci->sc_state_lock);
-		refrigerator();
+		try_to_freeze();
 		spin_lock(&sci->sc_state_lock);
 	} else {
 		DEFINE_WAIT(wait);

fs/xfs/xfs_buf.c

@@ -1703,7 +1703,7 @@ xfsbufd(
 
 		if (unlikely(freezing(current))) {
 			set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
-			refrigerator();
+			try_to_freeze();
 		} else {
 			clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
 		}

include/linux/freezer.h

@@ -5,71 +5,58 @@
 
 #include <linux/sched.h>
 #include <linux/wait.h>
+#include <linux/atomic.h>
 
 #ifdef CONFIG_FREEZER
+extern atomic_t system_freezing_cnt;	/* nr of freezing conds in effect */
+extern bool pm_freezing;		/* PM freezing in effect */
+extern bool pm_nosig_freezing;		/* PM nosig freezing in effect */
+
 /*
  * Check if a process has been frozen
  */
-static inline int frozen(struct task_struct *p)
+static inline bool 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 test_tsk_thread_flag(p, TIF_FREEZE);
-}
-
-/*
- * Request that a process be frozen
- */
-static inline void set_freeze_flag(struct task_struct *p)
-{
-	set_tsk_thread_flag(p, TIF_FREEZE);
-}
+extern bool freezing_slow_path(struct task_struct *p);
 
 /*
- * Sometimes we may need to cancel the previous 'freeze' request
+ * Check if there is a request to freeze a process
  */
-static inline void clear_freeze_flag(struct task_struct *p)
-{
-	clear_tsk_thread_flag(p, TIF_FREEZE);
-}
-
-static inline bool should_send_signal(struct task_struct *p)
+static inline bool freezing(struct task_struct *p)
 {
-	return !(p->flags & PF_FREEZER_NOSIG);
+	if (likely(!atomic_read(&system_freezing_cnt)))
+		return false;
+	return freezing_slow_path(p);
 }
 
 /* Takes and releases task alloc lock using task_lock() */
-extern int thaw_process(struct task_struct *p);
+extern void __thaw_task(struct task_struct *t);
 
-extern void refrigerator(void);
+extern bool __refrigerator(bool check_kthr_stop);
 extern int freeze_processes(void);
 extern int freeze_kernel_threads(void);
 extern void thaw_processes(void);
 
-static inline int try_to_freeze(void)
+static inline bool try_to_freeze(void)
 {
-	if (freezing(current)) {
-		refrigerator();
-		return 1;
-	} else
-		return 0;
+	might_sleep();
+	if (likely(!freezing(current)))
+		return false;
+	return __refrigerator(false);
 }
 
-extern bool freeze_task(struct task_struct *p, bool sig_only);
-extern void cancel_freezing(struct task_struct *p);
+extern bool freeze_task(struct task_struct *p);
+extern bool set_freezable(void);
 
 #ifdef CONFIG_CGROUP_FREEZER
-extern int cgroup_freezing_or_frozen(struct task_struct *task);
+extern bool cgroup_freezing(struct task_struct *task);
 #else /* !CONFIG_CGROUP_FREEZER */
-static inline int cgroup_freezing_or_frozen(struct task_struct *task)
+static inline bool cgroup_freezing(struct task_struct *task)
 {
-	return 0;
+	return false;
 }
 #endif /* !CONFIG_CGROUP_FREEZER */
 
@@ -117,23 +104,6 @@ static inline int freezer_should_skip(struct task_struct *p)
 	return !!(p->flags & PF_FREEZER_SKIP);
 }
 
-/*
- * Tell the freezer that the current task should be frozen by it
- */
-static inline void set_freezable(void)
-{
-	current->flags &= ~PF_NOFREEZE;
-}
-
-/*
- * Tell the freezer that the current task should be frozen by it and that it
- * should send a fake signal to the task to freeze it.
- */
-static inline void set_freezable_with_signal(void)
-{
-	current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
-}
-
 /*
  * Freezer-friendly wrappers around wait_event_interruptible(),
  * wait_event_killable() and wait_event_interruptible_timeout(), originally
@@ -152,47 +122,45 @@ static inline void set_freezable_with_signal(void)
 #define wait_event_freezable(wq, condition)				\
 ({									\
 	int __retval;							\
-	do {								\
+	for (;;) {							\
 		__retval = wait_event_interruptible(wq, 		\
 				(condition) || freezing(current));	\
-		if (__retval && !freezing(current))			\
+		if (__retval || (condition))				\
 			break;						\
-		else if (!(condition))					\
-			__retval = -ERESTARTSYS;			\
-	} while (try_to_freeze());					\
+		try_to_freeze();					\
+	}								\
 	__retval;							\
 })
 
-
 #define wait_event_freezable_timeout(wq, condition, timeout)		\
 ({									\
 	long __retval = timeout;					\
-	do {								\
+	for (;;) {							\
 		__retval = wait_event_interruptible_timeout(wq,		\
 				(condition) || freezing(current),	\
 				__retval); 				\
-	} while (try_to_freeze());					\
+		if (__retval <= 0 || (condition))			\
+			break;						\
+		try_to_freeze();					\
+	}								\
 	__retval;							\
 })
+
 #else /* !CONFIG_FREEZER */
-static inline int frozen(struct task_struct *p) { return 0; }
-static inline int freezing(struct task_struct *p) { return 0; }
-static inline void set_freeze_flag(struct task_struct *p) {}
-static inline void clear_freeze_flag(struct task_struct *p) {}
-static inline int thaw_process(struct task_struct *p) { return 1; }
+static inline bool frozen(struct task_struct *p) { return false; }
+static inline bool freezing(struct task_struct *p) { return false; }
 
-static inline void refrigerator(void) {}
+static inline bool __refrigerator(bool check_kthr_stop) { return false; }
 static inline int freeze_processes(void) { return -ENOSYS; }
 static inline int freeze_kernel_threads(void) { return -ENOSYS; }
 static inline void thaw_processes(void) {}
 
-static inline int try_to_freeze(void) { return 0; }
+static inline bool try_to_freeze(void) { return false; }
 
 static inline void freezer_do_not_count(void) {}
 static inline void freezer_count(void) {}
 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 static inline void set_freezable(void) {}
-static inline void set_freezable_with_signal(void) {}
 
 #define wait_event_freezable(wq, condition)				\
 		wait_event_interruptible(wq, condition)

include/linux/kthread.h

@@ -35,6 +35,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 int kthread_stop(struct task_struct *k);
 int kthread_should_stop(void);
+bool kthread_freezable_should_stop(bool *was_frozen);
 void *kthread_data(struct task_struct *k);
 
 int kthreadd(void *unused);

include/linux/sched.h

@@ -220,7 +220,7 @@ extern char ___assert_task_state[1 - 2*!!(
 			((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
 #define task_contributes_to_load(task)	\
 				((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
-				 (task->flags & PF_FREEZING) == 0)
+				 (task->flags & PF_FROZEN) == 0)
 
 #define __set_task_state(tsk, state_value)		\
 	do { (tsk)->state = (state_value); } while (0)
@@ -1772,7 +1772,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #define PF_MEMALLOC	0x00000800	/* Allocating memory */
 #define PF_NPROC_EXCEEDED 0x00001000	/* set_user noticed that RLIMIT_NPROC was exceeded */
 #define PF_USED_MATH	0x00002000	/* if unset the fpu must be initialized before use */
-#define PF_FREEZING	0x00004000	/* freeze in progress. do not account to load */
 #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 */
@@ -1788,7 +1787,6 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
 #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 freezable */
-#define PF_FREEZER_NOSIG 0x80000000	/* Freezer won't send signals to it */
 
 /*
  * Only the _current_ task can read/write to tsk->flags, but other

kernel/cgroup_freezer.c

@@ -48,19 +48,17 @@ static inline struct freezer *task_freezer(struct task_struct *task)
 			    struct freezer, css);
 }
 
-static inline int __cgroup_freezing_or_frozen(struct task_struct *task)
+bool cgroup_freezing(struct task_struct *task)
 {
-	enum freezer_state state = task_freezer(task)->state;
-	return (state == CGROUP_FREEZING) || (state == CGROUP_FROZEN);
-}
+	enum freezer_state state;
+	bool ret;
 
-int cgroup_freezing_or_frozen(struct task_struct *task)
-{
-	int result;
-	task_lock(task);
-	result = __cgroup_freezing_or_frozen(task);
-	task_unlock(task);
-	return result;
+	rcu_read_lock();
+	state = task_freezer(task)->state;
+	ret = state == CGROUP_FREEZING || state == CGROUP_FROZEN;
+	rcu_read_unlock();
+
+	return ret;
 }
 
 /*
@@ -102,9 +100,6 @@ struct cgroup_subsys freezer_subsys;
  * freezer_can_attach():
  * cgroup_mutex (held by caller of can_attach)
  *
- * cgroup_freezing_or_frozen():
- * task->alloc_lock (to get task's cgroup)
- *
  * freezer_fork() (preserving fork() performance means can't take cgroup_mutex):
  * freezer->lock
  *  sighand->siglock (if the cgroup is freezing)
@@ -130,7 +125,7 @@ struct cgroup_subsys freezer_subsys;
  *   write_lock css_set_lock (cgroup iterator start)
  *    task->alloc_lock
  *   read_lock css_set_lock (cgroup iterator start)
- *    task->alloc_lock (inside thaw_process(), prevents race with refrigerator())
+ *    task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())
  *     sighand->siglock
  */
 static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
@@ -150,7 +145,11 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
 static void freezer_destroy(struct cgroup_subsys *ss,
 			    struct cgroup *cgroup)
 {
-	kfree(cgroup_freezer(cgroup));
+	struct freezer *freezer = cgroup_freezer(cgroup);
+
+	if (freezer->state != CGROUP_THAWED)
+		atomic_dec(&system_freezing_cnt);
+	kfree(freezer);
 }
 
 /*
@@ -177,13 +176,7 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
 
 static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
 {
-	rcu_read_lock();
-	if (__cgroup_freezing_or_frozen(tsk)) {
-		rcu_read_unlock();
-		return -EBUSY;
-	}
-	rcu_read_unlock();
-	return 0;
+	return cgroup_freezing(tsk) ? -EBUSY : 0;
 }
 
 static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
@@ -213,7 +206,7 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
 
 	/* Locking avoids race with FREEZING -> THAWED transitions. */
 	if (freezer->state == CGROUP_FREEZING)
-		freeze_task(task, true);
+		freeze_task(task);
 	spin_unlock_irq(&freezer->lock);
 }
 
@@ -231,7 +224,7 @@ static void update_if_frozen(struct cgroup *cgroup,
 	cgroup_iter_start(cgroup, &it);
 	while ((task = cgroup_iter_next(cgroup, &it))) {
 		ntotal++;
-		if (frozen(task))
+		if (freezing(task) && frozen(task))
 			nfrozen++;
 	}
 
@@ -279,10 +272,9 @@ static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
 	struct task_struct *task;
 	unsigned int num_cant_freeze_now = 0;
 
-	freezer->state = CGROUP_FREEZING;
 	cgroup_iter_start(cgroup, &it);
 	while ((task = cgroup_iter_next(cgroup, &it))) {
-		if (!freeze_task(task, true))
+		if (!freeze_task(task))
 			continue;
 		if (frozen(task))
 			continue;
@@ -300,12 +292,9 @@ static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
 	struct task_struct *task;
 
 	cgroup_iter_start(cgroup, &it);
-	while ((task = cgroup_iter_next(cgroup, &it))) {
-		thaw_process(task);
-	}
+	while ((task = cgroup_iter_next(cgroup, &it)))
+		__thaw_task(task);
 	cgroup_iter_end(cgroup, &it);
-
-	freezer->state = CGROUP_THAWED;
 }
 
 static int freezer_change_state(struct cgroup *cgroup,
@@ -319,20 +308,24 @@ static int freezer_change_state(struct cgroup *cgroup,
 	spin_lock_irq(&freezer->lock);
 
 	update_if_frozen(cgroup, freezer);
-	if (goal_state == freezer->state)
-		goto out;
 
 	switch (goal_state) {
 	case CGROUP_THAWED:
+		if (freezer->state != CGROUP_THAWED)
+			atomic_dec(&system_freezing_cnt);
+		freezer->state = CGROUP_THAWED;
 		unfreeze_cgroup(cgroup, freezer);
 		break;
 	case CGROUP_FROZEN:
+		if (freezer->state == CGROUP_THAWED)
+			atomic_inc(&system_freezing_cnt);
+		freezer->state = CGROUP_FREEZING;
 		retval = try_to_freeze_cgroup(cgroup, freezer);
 		break;
 	default:
 		BUG();
 	}
-out:
+
 	spin_unlock_irq(&freezer->lock);
 
 	return retval;

kernel/exit.c

@@ -679,8 +679,6 @@ static void exit_mm(struct task_struct * tsk)
 	tsk->mm = NULL;
 	up_read(&mm->mmap_sem);
 	enter_lazy_tlb(mm, current);
-	/* We don't want this task to be frozen prematurely */
-	clear_freeze_flag(tsk);
 	task_unlock(tsk);
 	mm_update_next_owner(mm);
 	mmput(mm);
@@ -1040,6 +1038,7 @@ NORET_TYPE void do_exit(long code)
 	exit_rcu();
 	/* causes final put_task_struct in finish_task_switch(). */
 	tsk->state = TASK_DEAD;
+	tsk->flags |= PF_NOFREEZE;	/* tell freezer to ignore us */
 	schedule();
 	BUG();
 	/* Avoid "noreturn function does return".  */

kernel/fork.c

@@ -992,7 +992,6 @@ static void copy_flags(unsigned long clone_flags, struct task_struct *p)
 	new_flags |= PF_FORKNOEXEC;
 	new_flags |= PF_STARTING;
 	p->flags = new_flags;
-	clear_freeze_flag(p);
 }
 
 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)

kernel/freezer.c

@@ -9,101 +9,114 @@
 #include <linux/export.h>
 #include <linux/syscalls.h>
 #include <linux/freezer.h>
+#include <linux/kthread.h>
 
-/*
- * freezing is complete, mark current process as frozen
+/* total number of freezing conditions in effect */
+atomic_t system_freezing_cnt = ATOMIC_INIT(0);
+EXPORT_SYMBOL(system_freezing_cnt);
+
+/* indicate whether PM freezing is in effect, protected by pm_mutex */
+bool pm_freezing;
+bool pm_nosig_freezing;
+
+/* protects freezing and frozen transitions */
+static DEFINE_SPINLOCK(freezer_lock);
+
+/**
+ * freezing_slow_path - slow path for testing whether a task needs to be frozen
+ * @p: task to be tested
+ *
+ * This function is called by freezing() if system_freezing_cnt isn't zero
+ * and tests whether @p needs to enter and stay in frozen state.  Can be
+ * called under any context.  The freezers are responsible for ensuring the
+ * target tasks see the updated state.
  */
-static inline void frozen_process(void)
+bool freezing_slow_path(struct task_struct *p)
 {
-	if (!unlikely(current->flags & PF_NOFREEZE)) {
-		current->flags |= PF_FROZEN;
-		smp_wmb();
-	}
-	clear_freeze_flag(current);
+	if (p->flags & PF_NOFREEZE)
+		return false;
+
+	if (pm_nosig_freezing || cgroup_freezing(p))
+		return true;
+
+	if (pm_freezing && !(p->flags & PF_KTHREAD))
+		return true;
+
+	return false;
 }
+EXPORT_SYMBOL(freezing_slow_path);
 
 /* Refrigerator is place where frozen processes are stored :-). */
-void refrigerator(void)
+bool __refrigerator(bool check_kthr_stop)
 {
 	/* Hmm, should we be allowed to suspend when there are realtime
 	   processes around? */
-	long save;
+	bool was_frozen = false;
+	long save = current->state;
 
-	task_lock(current);
-	if (freezing(current)) {
-		frozen_process();
-		task_unlock(current);
-	} else {
-		task_unlock(current);
-		return;
-	}
-	save = current->state;
 	pr_debug("%s entered refrigerator\n", current->comm);
 
-	spin_lock_irq(&current->sighand->siglock);
-	recalc_sigpending(); /* We sent fake signal, clean it up */
-	spin_unlock_irq(&current->sighand->siglock);
-
-	/* prevent accounting of that task to load */
-	current->flags |= PF_FREEZING;
-
 	for (;;) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
-		if (!frozen(current))
+
+		spin_lock_irq(&freezer_lock);
+		current->flags |= PF_FROZEN;
+		if (!freezing(current) ||
+		    (check_kthr_stop && kthread_should_stop()))
+			current->flags &= ~PF_FROZEN;
+		spin_unlock_irq(&freezer_lock);
+
+		if (!(current->flags & PF_FROZEN))
 			break;
+		was_frozen = true;
 		schedule();
 	}
 
-	/* Remove the accounting blocker */
-	current->flags &= ~PF_FREEZING;
-
 	pr_debug("%s left refrigerator\n", current->comm);
-	__set_current_state(save);
+
+	/*
+	 * Restore saved task state before returning.  The mb'd version
+	 * needs to be used; otherwise, it might silently break
+	 * synchronization which depends on ordered task state change.
+	 */
+	set_current_state(save);
+
+	return was_frozen;
 }
-EXPORT_SYMBOL(refrigerator);
+EXPORT_SYMBOL(__refrigerator);
 
 static void fake_signal_wake_up(struct task_struct *p)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&p->sighand->siglock, flags);
-	signal_wake_up(p, 0);
-	spin_unlock_irqrestore(&p->sighand->siglock, flags);
+	if (lock_task_sighand(p, &flags)) {
+		signal_wake_up(p, 0);
+		unlock_task_sighand(p, &flags);
+	}
 }
 
 /**
- *	freeze_task - send a freeze request to given task
- *	@p: task to send the request to
- *	@sig_only: if set, the request will only be sent if the task has the
- *		PF_FREEZER_NOSIG flag unset
- *	Return value: 'false', if @sig_only is set and the task has
- *		PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
+ * freeze_task - send a freeze request to given task
+ * @p: task to send the request to
+ *
+ * If @p is freezing, the freeze request is sent by setting %TIF_FREEZE
+ * flag and either sending a fake signal to it or waking it up, depending
+ * on whether it has %PF_FREEZER_NOSIG set.
  *
- *	The freeze request is sent by setting the tasks's TIF_FREEZE flag and
- *	either sending a fake signal to it or waking it up, depending on whether
- *	or not it has PF_FREEZER_NOSIG set.  If @sig_only is set and the task
- *	has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
- *	TIF_FREEZE flag will not be set.
+ * RETURNS:
+ * %false, if @p is not freezing or already frozen; %true, otherwise
  */
-bool freeze_task(struct task_struct *p, bool sig_only)
+bool freeze_task(struct task_struct *p)
 {
-	/*
-	 * We first check if the task is freezing and next if it has already
-	 * been frozen to avoid the race with frozen_process() which first marks
-	 * the task as frozen and next clears its TIF_FREEZE.
-	 */
-	if (!freezing(p)) {
-		smp_rmb();
-		if (frozen(p))
-			return false;
-
-		if (!sig_only || should_send_signal(p))
-			set_freeze_flag(p);
-		else
-			return false;
+	unsigned long flags;
+
+	spin_lock_irqsave(&freezer_lock, flags);
+	if (!freezing(p) || frozen(p)) {
+		spin_unlock_irqrestore(&freezer_lock, flags);
+		return false;
 	}
 
-	if (should_send_signal(p)) {
+	if (!(p->flags & PF_KTHREAD)) {
 		fake_signal_wake_up(p);
 		/*
 		 * fake_signal_wake_up() goes through p's scheduler
@@ -111,56 +124,48 @@ bool freeze_task(struct task_struct *p, bool sig_only)
 		 * TASK_RUNNING transition can't race with task state
 		 * testing in try_to_freeze_tasks().
 		 */
-	} else if (sig_only) {
-		return false;
 	} else {
 		wake_up_state(p, TASK_INTERRUPTIBLE);
 	}
 
+	spin_unlock_irqrestore(&freezer_lock, flags);
 	return true;
 }
 
-void cancel_freezing(struct task_struct *p)
+void __thaw_task(struct task_struct *p)
 {
 	unsigned long flags;
 
-	if (freezing(p)) {
-		pr_debug("  clean up: %s\n", p->comm);
-		clear_freeze_flag(p);
-		spin_lock_irqsave(&p->sighand->siglock, flags);
-		recalc_sigpending_and_wake(p);
-		spin_unlock_irqrestore(&p->sighand->siglock, flags);
-	}
-}
-
-static int __thaw_process(struct task_struct *p)
-{
-	if (frozen(p)) {
-		p->flags &= ~PF_FROZEN;
-		return 1;
-	}
-	clear_freeze_flag(p);
-	return 0;
+	/*
+	 * Clear freezing and kick @p if FROZEN.  Clearing is guaranteed to
+	 * be visible to @p as waking up implies wmb.  Waking up inside
+	 * freezer_lock also prevents wakeups from leaking outside
+	 * refrigerator.
+	 */
+	spin_lock_irqsave(&freezer_lock, flags);
+	if (frozen(p))
+		wake_up_process(p);
+	spin_unlock_irqrestore(&freezer_lock, flags);
 }
 
-/*
- * Wake up a frozen process
+/**
+ * set_freezable - make %current freezable
  *
- * task_lock() is needed to prevent the race with refrigerator() which may
- * occur if the freezing of tasks fails.  Namely, without the lock, if the
- * freezing of tasks failed, thaw_tasks() might have run before a task in
- * refrigerator() could call frozen_process(), in which case the task would be
- * frozen and no one would thaw it.
+ * Mark %current freezable and enter refrigerator if necessary.
  */
-int thaw_process(struct task_struct *p)
+bool set_freezable(void)
 {
-	task_lock(p);
-	if (__thaw_process(p) == 1) {
-		task_unlock(p);
-		wake_up_process(p);
-		return 1;
-	}
-	task_unlock(p);
-	return 0;
+	might_sleep();
+
+	/*
+	 * Modify flags while holding freezer_lock.  This ensures the
+	 * freezer notices that we aren't frozen yet or the freezing
+	 * condition is visible to try_to_freeze() below.
+	 */
+	spin_lock_irq(&freezer_lock);
+	current->flags &= ~PF_NOFREEZE;
+	spin_unlock_irq(&freezer_lock);
+
+	return try_to_freeze();
 }
-EXPORT_SYMBOL(thaw_process);
+EXPORT_SYMBOL(set_freezable);

kernel/kthread.c

@@ -58,6 +58,31 @@ int kthread_should_stop(void)
 }
 EXPORT_SYMBOL(kthread_should_stop);
 
+/**
+ * kthread_freezable_should_stop - should this freezable kthread return now?
+ * @was_frozen: optional out parameter, indicates whether %current was frozen
+ *
+ * kthread_should_stop() for freezable kthreads, which will enter
+ * refrigerator if necessary.  This function is safe from kthread_stop() /
+ * freezer deadlock and freezable kthreads should use this function instead
+ * of calling try_to_freeze() directly.
+ */
+bool kthread_freezable_should_stop(bool *was_frozen)
+{
+	bool frozen = false;
+
+	might_sleep();
+
+	if (unlikely(freezing(current)))
+		frozen = __refrigerator(true);
+
+	if (was_frozen)
+		*was_frozen = frozen;
+
+	return kthread_should_stop();
+}
+EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
+
 /**
  * kthread_data - return data value specified on kthread creation
  * @task: kthread task in question
@@ -257,7 +282,7 @@ int kthreadd(void *unused)
 	set_cpus_allowed_ptr(tsk, cpu_all_mask);
 	set_mems_allowed(node_states[N_HIGH_MEMORY]);
 
-	current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
+	current->flags |= PF_NOFREEZE;
 
 	for (;;) {
 		set_current_state(TASK_INTERRUPTIBLE);

kernel/power/hibernate.c

@@ -611,17 +611,6 @@ static void power_down(void)
 	while(1);
 }
 
-static int prepare_processes(void)
-{
-	int error = 0;
-
-	if (freeze_processes()) {
-		error = -EBUSY;
-		thaw_processes();
-	}
-	return error;
-}
-
 /**
  * hibernate - Carry out system hibernation, including saving the image.
  */
@@ -654,7 +643,7 @@ int hibernate(void)
 	sys_sync();
 	printk("done.\n");
 
-	error = prepare_processes();
+	error = freeze_processes();
 	if (error)
 		goto Finish;
 
@@ -815,7 +804,7 @@ static int software_resume(void)
 		goto close_finish;
 
 	pr_debug("PM: Preparing processes for restore.\n");
-	error = prepare_processes();
+	error = freeze_processes();
 	if (error) {
 		swsusp_close(FMODE_READ);
 		goto Done;

kernel/power/process.c

@@ -22,16 +22,7 @@
  */
 #define TIMEOUT	(20 * HZ)
 
-static inline int freezable(struct task_struct * p)
-{
-	if ((p == current) ||
-	    (p->flags & PF_NOFREEZE) ||
-	    (p->exit_state != 0))
-		return 0;
-	return 1;
-}
-
-static int try_to_freeze_tasks(bool sig_only)
+static int try_to_freeze_tasks(bool user_only)
 {
 	struct task_struct *g, *p;
 	unsigned long end_time;
@@ -46,17 +37,14 @@ static int try_to_freeze_tasks(bool sig_only)
 
 	end_time = jiffies + TIMEOUT;
 
-	if (!sig_only)
+	if (!user_only)
 		freeze_workqueues_begin();
 
 	while (true) {
 		todo = 0;
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
-			if (frozen(p) || !freezable(p))
-				continue;
-
-			if (!freeze_task(p, sig_only))
+			if (p == current || !freeze_task(p))
 				continue;
 
 			/*
@@ -77,7 +65,7 @@ static int try_to_freeze_tasks(bool sig_only)
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
 
-		if (!sig_only) {
+		if (!user_only) {
 			wq_busy = freeze_workqueues_busy();
 			todo += wq_busy;
 		}
@@ -103,11 +91,6 @@ static int try_to_freeze_tasks(bool sig_only)
 	elapsed_csecs = elapsed_csecs64;
 
 	if (todo) {
-		/* This does not unfreeze processes that are already frozen
-		 * (we have slightly ugly calling convention in that respect,
-		 * and caller must call thaw_processes() if something fails),
-		 * but it cleans up leftover PF_FREEZE requests.
-		 */
 		printk("\n");
 		printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds "
 		       "(%d tasks refusing to freeze, wq_busy=%d):\n",
@@ -115,15 +98,11 @@ static int try_to_freeze_tasks(bool sig_only)
 		       elapsed_csecs / 100, elapsed_csecs % 100,
 		       todo - wq_busy, wq_busy);
 
-		thaw_workqueues();
-
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
-			task_lock(p);
-			if (!wakeup && freezing(p) && !freezer_should_skip(p))
+			if (!wakeup && !freezer_should_skip(p) &&
+			    p != current && freezing(p) && !frozen(p))
 				sched_show_task(p);
-			cancel_freezing(p);
-			task_unlock(p);
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);
 	} else {
@@ -136,12 +115,18 @@ static int try_to_freeze_tasks(bool sig_only)
 
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
+ *
+ * On success, returns 0.  On failure, -errno and system is fully thawed.
  */
 int freeze_processes(void)
 {
 	int error;
 
+	if (!pm_freezing)
+		atomic_inc(&system_freezing_cnt);
+
 	printk("Freezing user space processes ... ");
+	pm_freezing = true;
 	error = try_to_freeze_tasks(true);
 	if (!error) {
 		printk("done.");
@@ -150,17 +135,22 @@ int freeze_processes(void)
 	printk("\n");
 	BUG_ON(in_atomic());
 
+	if (error)
+		thaw_processes();
 	return error;
 }
 
 /**
  * freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
+ *
+ * On success, returns 0.  On failure, -errno and system is fully thawed.
  */
 int freeze_kernel_threads(void)
 {
 	int error;
 
 	printk("Freezing remaining freezable tasks ... ");
+	pm_nosig_freezing = true;
 	error = try_to_freeze_tasks(false);
 	if (!error)
 		printk("done.");
@@ -168,37 +158,32 @@ int freeze_kernel_threads(void)
 	printk("\n");
 	BUG_ON(in_atomic());
 
+	if (error)
+		thaw_processes();
 	return error;
 }
 
-static void thaw_tasks(bool nosig_only)
+void thaw_processes(void)
 {
 	struct task_struct *g, *p;
 
-	read_lock(&tasklist_lock);
-	do_each_thread(g, p) {
-		if (!freezable(p))
-			continue;
+	if (pm_freezing)
+		atomic_dec(&system_freezing_cnt);
+	pm_freezing = false;
+	pm_nosig_freezing = false;
 
-		if (nosig_only && should_send_signal(p))
-			continue;
+	oom_killer_enable();
+
+	printk("Restarting tasks ... ");
 
-		if (cgroup_freezing_or_frozen(p))
-			continue;
+	thaw_workqueues();
 
-		thaw_process(p);
+	read_lock(&tasklist_lock);
+	do_each_thread(g, p) {
+		__thaw_task(p);
 	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
-}
 
-void thaw_processes(void)
-{
-	oom_killer_enable();
-
-	printk("Restarting tasks ... ");
-	thaw_workqueues();
-	thaw_tasks(true);
-	thaw_tasks(false);
 	schedule();
 	printk("done.\n");
 }

kernel/power/suspend.c

@@ -106,13 +106,11 @@ static int suspend_prepare(void)
 		goto Finish;
 
 	error = suspend_freeze_processes();
-	if (error) {
-		suspend_stats.failed_freeze++;
-		dpm_save_failed_step(SUSPEND_FREEZE);
-	} else
+	if (!error)
 		return 0;
 
-	suspend_thaw_processes();
+	suspend_stats.failed_freeze++;
+	dpm_save_failed_step(SUSPEND_FREEZE);
 	usermodehelper_enable();
  Finish:
 	pm_notifier_call_chain(PM_POST_SUSPEND);

kernel/power/user.c

@@ -257,10 +257,8 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 			break;
 
 		error = freeze_processes();
-		if (error) {
-			thaw_processes();
+		if (error)
 			usermodehelper_enable();
-		}
 		if (!error)
 			data->frozen = 1;
 		break;

mm/backing-dev.c

@@ -600,14 +600,10 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 
 	/*
 	 * Finally, kill the kernel thread. We don't need to be RCU
-	 * safe anymore, since the bdi is gone from visibility. Force
-	 * unfreeze of the thread before calling kthread_stop(), otherwise
-	 * it would never exet if it is currently stuck in the refrigerator.
+	 * safe anymore, since the bdi is gone from visibility.
 	 */
-	if (bdi->wb.task) {
-		thaw_process(bdi->wb.task);
+	if (bdi->wb.task)
 		kthread_stop(bdi->wb.task);
-	}
 }
 
 /*

mm/oom_kill.c

@@ -328,7 +328,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
 		 */
 		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
 			if (unlikely(frozen(p)))
-				thaw_process(p);
+				__thaw_task(p);
 			return ERR_PTR(-1UL);
 		}
 		if (!p->mm)