[PATCH -rt 2/5] Thread Migration Preemption - v2

Peter Zijlstra
2007-07-14T16:03:37Z

[-- Attachment #1: thread-migration.patch --]
[-- Type: text/plain, Size: 48685 bytes --]

From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

This patch adds the ability to protect critical sections from migration to
another CPU without disabling preemption.

This will be useful to minimize the amount of preemption disabling for the -rt
patch. It will help leveraging improvements brought by the local_t types in
asm/local.h (see Documentation/local_ops.txt). Note that the updates done to
variables protected by migrate_disable must be either atomic or protected from
concurrent updates done by other threads.

Typical use:

migrate_disable();
local_inc(&__get_cpu_var(&my_local_t_var));
migrate_enable();

Which will increment the variable atomically wrt the local CPU.

Changes:

Do a check_migrate() upon migrate_enable() to answer to the migration
thread waiting for us to exit the migration disabled critical section. Use a
NEED_MIGRATE thread flag for this.

Note: (or we could say FIXME)
Is we ever want to check migration pending in assembly code, we will have to
make sure we test the right thread flag bits on each architectures. Care should
also be taken to check that the thread flags used won't trigger false positives
in non selective asm thread flag checks.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/asm-alpha/thread_info.h | 3 +
include/asm-arm/thread_info.h | 5 +
include/asm-arm26/thread_info.h | 5 +
include/asm-avr32/thread_info.h | 4 +
include/asm-blackfin/thread_info.h | 4 +
include/asm-cris/thread_info.h | 4 +
include/asm-frv/thread_info.h | 4 +
include/asm-h8300/thread_info.h | 4 +
include/asm-i386/thread_info.h | 6 +-
include/asm-ia64/thread_info.h | 4 +
include/asm-m32r/thread_info.h | 4 +
include/asm-m68k/thread_info.h | 2
include/asm-m68knommu/thread_info.h | 3 +
include/asm-mips/thread_info.h | 4 +
include/asm-parisc/thread_info.h | 4 +
include/asm-powerpc/thread_info.h | 4 +
include/asm-s390/thread_info.h | 4 +
include/asm-sh/thread_info.h | 4 +
include/asm-sh64/thread_info.h | 4 +
include/asm-sparc/thread_info.h | 4 +
include/asm-sparc64/thread_info.h | 5 +
include/asm-um/thread_info.h | 4 +
include/asm-v850/thread_info.h | 4 +
include/asm-x86_64/thread_info.h | 4 +
include/asm-xtensa/thread_info.h | 4 +
include/linux/preempt.h | 44 +++++++++++++++++
kernel/sched.c | 91 +++++++++++++++++++++++++++++++++---
lib/smp_processor_id.c | 6 +-
28 files changed, 230 insertions(+), 12 deletions(-)

Index: linux-2.6/include/asm-i386/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-i386/thread_info.h
+++ linux-2.6/include/asm-i386/thread_info.h
@@ -31,8 +31,7 @@ struct thread_info {
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
-
-
+ int migrate_count;/* 0: can migrate, <0: BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
0-0xFFFFFFFF for kernel-thread
@@ -74,6 +73,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -134,6 +134,7 @@ static inline struct thread_info *curren
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
#define TIF_NEED_RESCHED_DELAYED 10 /* reschedule on return to userspace */
+#define TIF_NEED_MIGRATE 11 /* migration necessary */
#define TIF_MEMDIE 16
#define TIF_DEBUG 17 /* uses debug registers */
#define TIF_IO_BITMAP 18 /* uses I/O bitmap */
@@ -151,6 +152,7 @@ static inline struct thread_info *curren
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_DEBUG (1<<TIF_DEBUG)
#define _TIF_IO_BITMAP (1<<TIF_IO_BITMAP)
#define _TIF_FREEZE (1<<TIF_FREEZE)
Index: linux-2.6/include/linux/preempt.h
===================================================================
--- linux-2.6.orig/include/linux/preempt.h
+++ linux-2.6/include/linux/preempt.h
@@ -15,6 +15,8 @@
extern void notrace sub_preempt_count(unsigned int val);
extern void notrace mask_preempt_count(unsigned int mask);
extern void notrace unmask_preempt_count(unsigned int mask);
+ extern void fastcall add_migrate_count(int val);
+ extern void fastcall sub_migrate_count(int val);
#else
# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
@@ -22,6 +24,8 @@
do { preempt_count() |= (mask); } while (0)
# define unmask_preempt_count(mask) \
do { preempt_count() &= ~(mask); } while (0)
+# define add_migrate_count(val) do { migrate_count() += (val); } while (0)
+# define sub_migrate_count(val) do { migrate_count() -= (val); } while (0)
#endif

#ifdef CONFIG_CRITICAL_TIMING
@@ -35,7 +39,12 @@
#define inc_preempt_count() add_preempt_count(1)
#define dec_preempt_count() sub_preempt_count(1)

-#define preempt_count() (current_thread_info()->preempt_count)
+#define preempt_count() (current_thread_info()->preempt_count)
+
+#define inc_migrate_count() add_migrate_count(1)
+#define dec_migrate_count() sub_migrate_count(1)
+
+#define migrate_count() (current_thread_info()->migrate_count)

#ifdef CONFIG_PREEMPT

@@ -80,6 +89,36 @@ do { \
preempt_check_resched(); \
} while (0)

+#define migrate_disable() \
+do { \
+ inc_migrate_count(); \
+ barrier(); \
+} while (0)
+
+#define migrate_enable_no_check() \
+do { \
+ barrier(); \
+ dec_migrate_count(); \
+} while (0)
+
+#ifdef CONFIG_SMP
+extern void do_check_migrate(void);
+#define check_migrate() \
+do { \
+ if (unlikely(test_thread_flag(TIF_NEED_MIGRATE))) \
+ do_check_migrate(); \
+} while (0)
+#else
+#define check_migrate()
+#endif
+
+#define migrate_enable() \
+do { \
+ migrate_enable_no_check(); \
+ barrier(); \
+ check_migrate(); \
+} while (0)
+
#else

#define preempt_disable() do { } while (0)
@@ -91,6 +130,9 @@ do { \

#define preempt_schedule_irq() do { } while (0)

+#define migrate_disable() do { } while (0)
+#define migrate_enable() do { } while (0)
+
#endif

#endif /* __LINUX_PREEMPT_H */
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -1175,7 +1175,8 @@ migrate_task(struct task_struct *p, int
* If the task is not on a runqueue (and not running), then
* it is sufficient to simply update the task's cpu field.
*/
- if (!p->se.on_rq && !task_running(rq, p)) {
+ if (!p->se.on_rq && !task_running(rq, p)
+ && !task_thread_info(p)->migrate_count) {
set_task_cpu(p, dest_cpu);
return 0;
}
@@ -1506,6 +1507,29 @@ static void balance_rt_tasks(struct rq *

#endif

+void fastcall add_migrate_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON((migrate_count() < 0)))
+ return;
+ migrate_count() += val;
+}
+EXPORT_SYMBOL(add_migrate_count);
+
+void fastcall sub_migrate_count(int val)
+{
+ /*
+ * Underflow?
+ */
+ if (DEBUG_LOCKS_WARN_ON(val > migrate_count()))
+ return;
+
+ migrate_count() -= val;
+}
+EXPORT_SYMBOL(sub_migrate_count);
+
/*
* find_idlest_cpu - find the idlest cpu among the cpus in group.
*/
@@ -1696,7 +1720,10 @@ try_to_wake_up(struct task_struct *p, un
#ifdef CONFIG_SMP
if (unlikely(task_running(rq, p)))
goto out_activate;
-
+#ifdef CONFIG_PREEMPT
+ if (task_thread_info(p)->migrate_count)
+ goto out_activate;
+#endif
new_cpu = cpu;

schedstat_inc(rq, ttwu_cnt);
@@ -1970,6 +1997,7 @@ void sched_fork(struct task_struct *p, i
#ifdef CONFIG_PREEMPT
/* Want to start with kernel preemption disabled. */
task_thread_info(p)->preempt_count = 1;
+ task_thread_info(p)->migrate_count = 0;
#endif
put_cpu();
}
@@ -2435,6 +2463,10 @@ static void sched_migrate_task(struct ta
if (!cpu_isset(dest_cpu, p->cpus_allowed)
|| unlikely(cpu_is_offline(dest_cpu)))
goto out;
+#ifdef CONFIG_PREEMPT
+ if (task_thread_info(p)->migrate_count)
+ goto out;
+#endif

/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
@@ -2496,6 +2528,7 @@ int can_migrate_task(struct task_struct
* 1) running (obviously), or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
+ * 4) migration preemption is non 0 for this non running task.
*/
if (!cpu_isset(this_cpu, p->cpus_allowed))
return 0;
@@ -2503,6 +2536,10 @@ int can_migrate_task(struct task_struct

if (task_running(rq, p))
return 0;
+#ifdef CONFIG_PREEMPT
+ if (task_thread_info(p)->migrate_count)
+ return 0;
+#endif

/*
* Aggressive migration if too many balance attempts have failed:
@@ -3822,6 +3859,27 @@ EXPORT_SYMBOL(schedule);

#ifdef CONFIG_PREEMPT

+#ifdef CONFIG_SMP
+/*
+ * Wake up the migration thread to deal with our pending migration.
+ * If we have been moved since, we will just wake up the migration thread from
+ * the wrong CPU, which does not hurt anyone. (that's why we use
+ * raw_smp_processor_id()).
+ */
+void __sched do_check_migrate(void)
+{
+ struct rq *rq;
+
+ if (migrate_count())
+ return;
+
+ clear_thread_flag(TIF_NEED_MIGRATE);
+ rq = cpu_rq(raw_smp_processor_id());
+ wake_up_process(rq->migration_thread);
+}
+EXPORT_SYMBOL(do_check_migrate);
+#endif
+
/*
* Global flag to turn preemption off on a CONFIG_PREEMPT kernel:
*/
@@ -5478,7 +5536,7 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed);
* So we race with normal scheduler movements, but that's OK, as long
* as the task is no longer on this CPU.
*
- * Returns non-zero if task was successfully migrated.
+ * Returns non-zero if task is on dest_cpu when this function ends.
*/
static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
{
@@ -5500,13 +5558,19 @@ static int __migrate_task(struct task_st

double_rq_lock(rq_src, rq_dest);
/* Already moved. */
- if (task_cpu(p) != src_cpu)
+ if (task_cpu(p) != src_cpu) {
+ ret = 1;
goto out;
+ }
/* Affinity changed (again). */
if (!cpu_isset(dest_cpu, p->cpus_allowed))
goto out;

on_rq = p->se.on_rq;
+#ifdef CONFIG_PREEMPT
+ if (!on_rq && task_thread_info(p)->migrate_count)
+ goto out;
+#endif
if (on_rq)
deactivate_task(rq_src, p, 0);

@@ -5532,6 +5596,7 @@ static int migration_thread(void *data)
{
int cpu = (long)data;
struct rq *rq;
+ int migrated;

rq = cpu_rq(cpu);
BUG_ON(rq->migration_thread != current);
@@ -5567,10 +5632,22 @@ static int migration_thread(void *data)
list_del_init(head->next);

spin_unlock(&rq->lock);
- __migrate_task(req->task, cpu, req->dest_cpu);
+ migrated = __migrate_task(req->task, cpu, req->dest_cpu);
local_irq_enable();
-
- complete(&req->done);
+ if (!migrated) {
+ /*
+ * If the process has not been migrated, let it run
+ * until it reaches a migration_check() so it can
+ * wake us up.
+ */
+ spin_lock_irq(&rq->lock);
+ head = &rq->migration_queue;
+ list_add(&req->list, head);
+ set_tsk_thread_flag(req->task, TIF_NEED_MIGRATE);
+ spin_unlock_irq(&rq->lock);
+ wake_up_process(req->task);
+ } else
+ complete(&req->done);
}
__set_current_state(TASK_RUNNING);
return 0;
Index: linux-2.6/include/asm-alpha/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-alpha/thread_info.h
+++ linux-2.6/include/asm-alpha/thread_info.h
@@ -21,6 +21,7 @@ struct thread_info {
mm_segment_t addr_limit; /* thread address space */
unsigned cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

int bpt_nsaved;
unsigned long bpt_addr[2]; /* breakpoint handling */
@@ -77,6 +78,7 @@ register struct thread_info *__current_t
#define TIF_UAC_SIGBUS 8
#define TIF_MEMDIE 9
#define TIF_RESTORE_SIGMASK 10 /* restore signal mask in do_signal */
+#define TIF_NEED_MIGRATE 11 /* migration necessary */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
@@ -84,6 +86,7 @@ register struct thread_info *__current_t
#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_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

/* Work to do on interrupt/exception return. */
#define _TIF_WORK_MASK (_TIF_NOTIFY_RESUME \
Index: linux-2.6/include/asm-arm/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-arm/thread_info.h
+++ linux-2.6/include/asm-arm/thread_info.h
@@ -51,6 +51,7 @@ struct cpu_context_save {
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -72,6 +73,7 @@ struct thread_info {
.exec_domain = &default_exec_domain, \
.flags = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.cpu_domain = domain_val(DOMAIN_USER, DOMAIN_MANAGER) | \
domain_val(DOMAIN_KERNEL, DOMAIN_MANAGER) | \
@@ -138,6 +140,7 @@ extern void iwmmxt_task_switch(struct th
* TIF_NOTIFY_RESUME - resumption notification requested
* TIF_SIGPENDING - signal pending
* TIF_NEED_RESCHED - rescheduling necessary
+ * TIF_NEED_MIGRATE - migration necessary
* TIF_USEDFPU - FPU was used by this task this quantum (SMP)
* TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED
*/
@@ -145,6 +148,7 @@ extern void iwmmxt_task_switch(struct th
#define TIF_SIGPENDING 1
#define TIF_NEED_RESCHED 2
#define TIF_NEED_RESCHED_DELAYED 3
+#define TIF_NEED_MIGRATE 4
#define TIF_SYSCALL_TRACE 8
#define TIF_POLLING_NRFLAG 16
#define TIF_USING_IWMMXT 17
@@ -155,6 +159,7 @@ extern void iwmmxt_task_switch(struct th
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NEED_RESCHED_DELAYED (1<<TIF_NEED_RESCHED_DELAYED)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
Index: linux-2.6/include/asm-arm26/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-arm26/thread_info.h
+++ linux-2.6/include/asm-arm26/thread_info.h
@@ -45,6 +45,7 @@ struct cpu_context_save {
struct thread_info {
unsigned long flags; /* low level flags */
int preempt_count; /* 0 => preemptable, <0 => bug */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -60,6 +61,7 @@ struct thread_info {
.exec_domain &default_exec_domain, \
.flags 0, \
.preempt_count 0, \
+ .migrate_count 0, \
.addr_limit KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -113,12 +115,14 @@ extern void free_thread_info(struct thre
* TIF_NOTIFY_RESUME - resumption notification requested
* TIF_SIGPENDING - signal pending
* TIF_NEED_RESCHED - rescheduling necessary
+ * TIF_NEED_MIGRATE - migration necessary
* TIF_USEDFPU - FPU was used by this task this quantum (SMP)
* TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED
*/
#define TIF_NOTIFY_RESUME 0
#define TIF_SIGPENDING 1
#define TIF_NEED_RESCHED 2
+#define TIF_NEED_MIGRATE 3
#define TIF_SYSCALL_TRACE 8
#define TIF_USED_FPU 16
#define TIF_POLLING_NRFLAG 17
@@ -127,6 +131,7 @@ extern void free_thread_info(struct thre
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_USED_FPU (1 << TIF_USED_FPU)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
Index: linux-2.6/include/asm-avr32/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-avr32/thread_info.h
+++ linux-2.6/include/asm-avr32/thread_info.h
@@ -25,6 +25,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
__u32 cpu;
__s32 preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
__u8 supervisor_stack[0];
};
@@ -36,6 +37,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall \
} \
@@ -84,6 +86,7 @@ static inline struct thread_info *curren
#define TIF_MEMDIE 7
#define TIF_RESTORE_SIGMASK 8 /* restore signal mask in do_signal */
#define TIF_CPU_GOING_TO_SLEEP 9 /* CPU is entering sleep 0 mode */
+#define TIF_NEED_MIGRATE 10 /* migration necessary */
#define TIF_USERSPACE 31 /* true if FS sets userspace */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
@@ -96,6 +99,7 @@ static inline struct thread_info *curren
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)

/* XXX: These two masks must never span more than 16 bits! */
/* work to do on interrupt/exception return */
Index: linux-2.6/include/asm-blackfin/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-blackfin/thread_info.h
+++ linux-2.6/include/asm-blackfin/thread_info.h
@@ -54,6 +54,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count; /* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* address limit */
struct restart_block restart_block;
struct l1_scratch_task_info l1_task_info;
@@ -69,6 +70,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -126,6 +128,7 @@ static inline struct thread_info *curren
#define TIF_MEMDIE 5
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
#define TIF_FREEZE 7 /* is freezing for suspend */
+#define TIF_NEED_MIGRATE 8 /* migration necessary */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -135,6 +138,7 @@ static inline struct thread_info *curren
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_FREEZE (1<<TIF_FREEZE)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

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

Index: linux-2.6/include/asm-cris/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-cris/thread_info.h
+++ linux-2.6/include/asm-cris/thread_info.h
@@ -32,6 +32,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -58,6 +59,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -82,6 +84,7 @@ struct thread_info {
#define TIF_NOTIFY_RESUME 1 /* resumption notification requested */
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
+#define TIF_NEED_MIGRATE 4 /* migration necessary */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17

@@ -90,6 +93,7 @@ struct thread_info {
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

#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/include/asm-frv/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-frv/thread_info.h
+++ linux-2.6/include/asm-frv/thread_info.h
@@ -36,6 +36,7 @@ struct thread_info {
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -68,6 +69,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -114,6 +116,7 @@ register struct thread_info *__current_t
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_IRET 5 /* return with iret */
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
+#define TIF_NEED_MIGRATE 7 /* migration necessary */
#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 */
@@ -127,6 +130,7 @@ register struct thread_info *__current_t
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_FREEZE (1 << TIF_FREEZE)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)

#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/include/asm-h8300/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-h8300/thread_info.h
+++ linux-2.6/include/asm-h8300/thread_info.h
@@ -24,6 +24,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -37,6 +38,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -92,6 +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_NEED_MIGRATE 6 /* migration necessary */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -99,6 +102,7 @@ static inline struct thread_info *curren
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

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

Index: linux-2.6/include/asm-ia64/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-ia64/thread_info.h
+++ linux-2.6/include/asm-ia64/thread_info.h
@@ -30,6 +30,7 @@ struct thread_info {
__u32 status; /* Thread synchronous flags */
mm_segment_t addr_limit; /* user-level address space limit */
int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */
+ int migrate_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -43,6 +44,7 @@ struct thread_info {
.cpu = 0, \
.addr_limit = KERNEL_DS, \
.preempt_count = 0, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -86,6 +88,7 @@ struct thread_info {
#define TIF_SYSCALL_AUDIT 4 /* syscall auditing active */
#define TIF_SINGLESTEP 5 /* restore singlestep on return to user mode */
#define TIF_RESTORE_SIGMASK 6 /* restore signal mask in do_signal() */
+#define TIF_NEED_MIGRATE 7 /* migration necessary */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
#define TIF_MEMDIE 17
#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
@@ -99,6 +102,7 @@ struct thread_info {
#define _TIF_SYSCALL_TRACEAUDIT (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
Index: linux-2.6/include/asm-m32r/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-m32r/thread_info.h
+++ linux-2.6/include/asm-m32r/thread_info.h
@@ -29,6 +29,7 @@ struct thread_info {
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thread
@@ -69,6 +70,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -151,6 +153,7 @@ static inline unsigned int get_thread_fa
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
#define TIF_IRET 5 /* return with iret */
+#define TIF_NEED_MIGRATE 6 /* migration necessary */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
/* 31..28 fault code */
#define TIF_MEMDIE 17
@@ -162,6 +165,7 @@ static inline unsigned int get_thread_fa
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_IRET (1<<TIF_IRET)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

#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/include/asm-m68k/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-m68k/thread_info.h
+++ linux-2.6/include/asm-m68k/thread_info.h
@@ -9,6 +9,7 @@ struct thread_info {
unsigned long flags;
struct exec_domain *exec_domain; /* execution domain */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
__u32 cpu; /* should always be 0 on m68k */
struct restart_block restart_block;
};
@@ -58,5 +59,6 @@ struct thread_info {
#define TIF_DELAYED_TRACE 14 /* single step a syscall */
#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
#define TIF_MEMDIE 16
+#define TIF_NEED_MIGRATE 17 /* migration necessary */

#endif /* _ASM_M68K_THREAD_INFO_H */
Index: linux-2.6/include/asm-m68knommu/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-m68knommu/thread_info.h
+++ linux-2.6/include/asm-m68knommu/thread_info.h
@@ -37,6 +37,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -89,6 +90,7 @@ 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_NEED_MIGRATE 6 /* migration necessary */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -96,6 +98,7 @@ static inline struct thread_info *curren
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

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

Index: linux-2.6/include/asm-mips/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-mips/thread_info.h
+++ linux-2.6/include/asm-mips/thread_info.h
@@ -28,6 +28,7 @@ struct thread_info {
unsigned long tp_value; /* thread pointer */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user-thead
@@ -49,6 +50,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -115,6 +117,7 @@ register struct thread_info *__current_t
#define TIF_SYSCALL_AUDIT 4 /* syscall auditing active */
#define TIF_SECCOMP 5 /* secure computing */
#define TIF_NEED_RESCHED_DELAYED 6 /* reschedule on return to userspace */
+#define TIF_NEED_MIGRATE 7 /* migration necessary */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */
#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 */
@@ -129,6 +132,7 @@ register struct thread_info *__current_t
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_NEED_RESCHED_DELAYED (1<<TIF_NEED_RESCHED_DELAYED)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
Index: linux-2.6/include/asm-parisc/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-parisc/thread_info.h
+++ linux-2.6/include/asm-parisc/thread_info.h
@@ -13,6 +13,7 @@ struct thread_info {
mm_segment_t addr_limit; /* user-level address space limit */
__u32 cpu; /* current CPU */
int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */
+ int migrate_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -24,6 +25,7 @@ struct thread_info {
.cpu = 0, \
.addr_limit = KERNEL_DS, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall \
} \
@@ -63,6 +65,7 @@ struct thread_info {
#define TIF_32BIT 5 /* 32 bit binary */
#define TIF_MEMDIE 6
#define TIF_RESTORE_SIGMASK 7 /* restore saved signal mask */
+#define TIF_NEED_MIGRATE 8 /* migration necessary */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@@ -71,6 +74,7 @@ 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_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)

#define _TIF_USER_WORK_MASK (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | \
_TIF_NEED_RESCHED | _TIF_RESTORE_SIGMASK)
Index: linux-2.6/include/asm-powerpc/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/thread_info.h
+++ linux-2.6/include/asm-powerpc/thread_info.h
@@ -35,6 +35,7 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migrate_count; /* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
unsigned long local_flags; /* private flags for thread */

@@ -53,6 +54,7 @@ struct thread_info {
.exec_domain = &default_exec_domain, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -124,6 +126,7 @@ static inline struct thread_info *curren
#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 */
+#define TIF_NEED_MIGRATE 17 /* migration necessary */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -143,6 +146,7 @@ static inline struct thread_info *curren
#define _TIF_FREEZE (1<<TIF_FREEZE)
#define _TIF_NEED_RESCHED_DELAYED (1<<TIF_NEED_RESCHED_DELAYED)

+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#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/include/asm-s390/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-s390/thread_info.h
+++ linux-2.6/include/asm-s390/thread_info.h
@@ -51,6 +51,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
unsigned int cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -64,6 +65,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -96,6 +98,7 @@ static inline struct thread_info *curren
#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
#define TIF_SINGLE_STEP 6 /* deliver sigtrap on return to user */
#define TIF_MCCK_PENDING 7 /* machine check handling is pending */
+#define TIF_NEED_MIGRATE 8 /* migration necessary */
#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 */
@@ -110,6 +113,7 @@ static inline struct thread_info *curren
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_SINGLE_STEP (1<<TIF_SINGLE_STEP)
#define _TIF_MCCK_PENDING (1<<TIF_MCCK_PENDING)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_31BIT (1<<TIF_31BIT)
Index: linux-2.6/include/asm-sh/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-sh/thread_info.h
+++ linux-2.6/include/asm-sh/thread_info.h
@@ -21,6 +21,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
__u32 cpu;
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
unsigned long previous_sp; /* sp of previous stack in case
@@ -58,6 +59,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -113,6 +115,7 @@ static inline struct thread_info *curren
#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
#define TIF_SINGLESTEP 5 /* singlestepping active */
#define TIF_NEED_RESCHED_DELAYED 6 /* reschedule on return to userspace */
+#define TIF_NEED_MIGRATE 7 /* migration necessary */
#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
@@ -125,6 +128,7 @@ static inline struct thread_info *curren
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_NEED_RESCHED_DELAYED (1<<TIF_NEED_RESCHED_DELAYED)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_FREEZE (1<<TIF_FREEZE)
Index: linux-2.6/include/asm-sh64/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-sh64/thread_info.h
+++ linux-2.6/include/asm-sh64/thread_info.h
@@ -23,6 +23,7 @@ struct thread_info {
unsigned long flags; /* low level flags */
/* Put the 4 32-bit fields together to make asm offsetting easier. */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
__u16 cpu;

mm_segment_t addr_limit;
@@ -41,6 +42,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -79,12 +81,14 @@ static inline struct thread_info *curren
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_MEMDIE 4
#define TIF_RESTORE_SIGMASK 5 /* Restore signal mask in do_signal */
+#define TIF_NEED_MIGRATE 6 /* migration necessary */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)

#endif /* __KERNEL__ */

Index: linux-2.6/include/asm-sparc/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-sparc/thread_info.h
+++ linux-2.6/include/asm-sparc/thread_info.h
@@ -33,6 +33,7 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
int softirq_count;
int hardirq_count;

@@ -65,6 +66,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -132,6 +134,7 @@ BTFIXUPDEF_CALL(void, free_thread_info,
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTORE_SIGMASK 4 /* restore signal mask in do_signal() */
+#define TIF_NEED_MIGRATE 5 /* migration necessary */
#define TIF_USEDFPU 8 /* FPU was used by this task
* this quantum (SMP) */
#define TIF_POLLING_NRFLAG 9 /* true if poll_idle() is polling
@@ -143,6 +146,7 @@ BTFIXUPDEF_CALL(void, free_thread_info,
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_USEDFPU (1<<TIF_USEDFPU)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)

Index: linux-2.6/include/asm-sparc64/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-sparc64/thread_info.h
+++ linux-2.6/include/asm-sparc64/thread_info.h
@@ -47,6 +47,7 @@ struct thread_info {
struct pt_regs *kregs;
struct exec_domain *exec_domain;
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
__u8 new_child;
__u8 syscall_noerror;
__u16 cpu;
@@ -137,6 +138,7 @@ struct thread_info {
.flags = ((unsigned long)ASI_P) << TI_FLAG_CURRENT_DS_SHIFT, \
.exec_domain = &default_exec_domain, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -225,7 +227,7 @@ register struct thread_info *current_thr
#define TIF_UNALIGNED 5 /* allowed to do unaligned accesses */
#define TIF_NEWSIGNALS 6 /* wants new-style signals */
#define TIF_32BIT 7 /* 32-bit binary */
-/* flag bit 8 is available */
+#define TIF_NEED_MIGRATE 8 /* migration necessary */
#define TIF_SECCOMP 9 /* secure computing */
#define TIF_SYSCALL_AUDIT 10 /* syscall auditing active */
/* flag bit 11 is available */
@@ -244,6 +246,7 @@ register struct thread_info *current_thr
#define _TIF_UNALIGNED (1<<TIF_UNALIGNED)
#define _TIF_NEWSIGNALS (1<<TIF_NEWSIGNALS)
#define _TIF_32BIT (1<<TIF_32BIT)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
Index: linux-2.6/include/asm-um/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-um/thread_info.h
+++ linux-2.6/include/asm-um/thread_info.h
@@ -18,6 +18,7 @@ struct thread_info {
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
mm_segment_t addr_limit; /* thread address space:
0-0xBFFFFFFF for user
0-0xFFFFFFFF for kernel */
@@ -32,6 +33,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -71,6 +73,7 @@ static inline struct thread_info *curren
#define TIF_MEMDIE 5
#define TIF_SYSCALL_AUDIT 6
#define TIF_RESTORE_SIGMASK 7
+#define TIF_NEED_MIGRATE 8 /* migration necessary */

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
@@ -79,5 +82,6 @@ static inline struct thread_info *curren
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
+#define _TIF_NEED_MIGRATE (1 << TIF_NEED_MIGRATE)

#endif
Index: linux-2.6/include/asm-v850/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-v850/thread_info.h
+++ linux-2.6/include/asm-v850/thread_info.h
@@ -32,6 +32,7 @@ struct thread_info {
int cpu; /* cpu we're on */
int preempt_count; /* 0 => preemptable,
<0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */
struct restart_block restart_block;
};

@@ -42,6 +43,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.restart_block = { \
.fn = do_no_restart_syscall, \
}, \
@@ -83,6 +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_NEED_MIGRATE 6 /* migration necessary */

/* as above, but as bit values */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -90,6 +93,7 @@ struct thread_info {
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)

/* Size of kernel stack for each process. */
Index: linux-2.6/include/asm-x86_64/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-x86_64/thread_info.h
+++ linux-2.6/include/asm-x86_64/thread_info.h
@@ -30,6 +30,7 @@ struct thread_info {
__u32 status; /* thread synchronous flags */
__u32 cpu; /* current CPU */
int preempt_count; /* 0 => preemptable, <0 => BUG */
+ int migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit;
struct restart_block restart_block;
@@ -48,6 +49,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -116,6 +118,7 @@ static inline struct thread_info *stack_
#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal */
+#define TIF_NEED_MIGRATE 11 /* migration necessary */
/* 16 free */
#define TIF_IA32 17 /* 32bit process */
#define TIF_FORK 18 /* ret_from_fork */
@@ -135,6 +138,7 @@ static inline struct thread_info *stack_
#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_NEED_RESCHED_DELAYED (1<<TIF_NEED_RESCHED_DELAYED)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_IA32 (1<<TIF_IA32)
#define _TIF_FORK (1<<TIF_FORK)
#define _TIF_ABI_PENDING (1<<TIF_ABI_PENDING)
Index: linux-2.6/include/asm-xtensa/thread_info.h
===================================================================
--- linux-2.6.orig/include/asm-xtensa/thread_info.h
+++ linux-2.6/include/asm-xtensa/thread_info.h
@@ -34,6 +34,7 @@ struct thread_info {
unsigned long status; /* thread-synchronous flags */
__u32 cpu; /* current CPU */
__s32 preempt_count; /* 0 => preemptable,< 0 => BUG*/
+ __s32 migrate_count;/* 0: can migrate, <0 => BUG */

mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
@@ -72,6 +73,7 @@ struct thread_info {
.flags = 0, \
.cpu = 0, \
.preempt_count = 1, \
+ .migrate_count = 0, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
@@ -117,6 +119,7 @@ static inline struct thread_info *curren
#define TIF_IRET 5 /* return with iret */
#define TIF_MEMDIE 6
#define TIF_RESTORE_SIGMASK 7 /* restore signal mask in do_signal() */
+#define TIF_NEED_MIGRATE 8 /* migration necessary */
#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -125,6 +128,7 @@ static inline struct thread_info *curren
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
#define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP)
#define _TIF_IRET (1<<TIF_IRET)
+#define _TIF_NEED_MIGRATE (1<<TIF_NEED_MIGRATE)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)

Index: linux-2.6/lib/smp_processor_id.c
===================================================================
--- linux-2.6.orig/lib/smp_processor_id.c
+++ linux-2.6/lib/smp_processor_id.c
@@ -10,12 +10,16 @@
unsigned int notrace debug_smp_processor_id(void)
{
unsigned long preempt_count = preempt_count();
+ unsigned long migrate_count = migrate_count();
int this_cpu = raw_smp_processor_id();
cpumask_t this_mask;

if (likely(preempt_count))
goto out;

+ if (likely(migrate_count))
+ goto out;
+
if (irqs_disabled())
goto out;

@@ -42,7 +46,7 @@ unsigned int notrace debug_smp_processor
if (!printk_ratelimit())
goto out_enable;

- printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count()-1, current->comm, current->pid);
+ printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] migration [%08x] code: %s/%d\n", preempt_count()-1, migrate_count(), current->comm, current->pid);
print_symbol("caller is %s\n", (long)__builtin_return_address(0));
dump_stack();

--