cleanups, speedups and fixes. Added support for non-current set_cpus_allowed().

arch/i386/kernel/i8259.c

@@ -79,7 +79,6 @@ BUILD_16_IRQS(0xc) BUILD_16_IRQS(0xd)
  * through the ICC by us (IPIs)
  */
 #ifdef CONFIG_SMP
-BUILD_SMP_INTERRUPT(task_migration_interrupt,TASK_MIGRATION_VECTOR)
 BUILD_SMP_INTERRUPT(reschedule_interrupt,RESCHEDULE_VECTOR)
 BUILD_SMP_INTERRUPT(invalidate_interrupt,INVALIDATE_TLB_VECTOR)
 BUILD_SMP_INTERRUPT(call_function_interrupt,CALL_FUNCTION_VECTOR)
@@ -474,9 +473,6 @@ void __init init_IRQ(void)
 	 */
 	set_intr_gate(RESCHEDULE_VECTOR, reschedule_interrupt);
 
-	/* IPI for task migration */
-	set_intr_gate(TASK_MIGRATION_VECTOR, task_migration_interrupt);
-
 	/* IPI for invalidation */
 	set_intr_gate(INVALIDATE_TLB_VECTOR, invalidate_interrupt);
 

arch/i386/kernel/smp.c

@@ -485,35 +485,6 @@ void flush_tlb_all(void)
 	do_flush_tlb_all_local();
 }
 
-static spinlock_t migration_lock = SPIN_LOCK_UNLOCKED;
-static task_t *new_task;
-
-/*
- * This function sends a 'task migration' IPI to another CPU.
- * Must be called from syscall contexts, with interrupts *enabled*.
- */
-void smp_migrate_task(int cpu, task_t *p)
-{
-	/*
-	 * The target CPU will unlock the migration spinlock:
-	 */
-	_raw_spin_lock(&migration_lock);
-	new_task = p;
-	send_IPI_mask(1 << cpu, TASK_MIGRATION_VECTOR);
-}
-
-/*
- * Task migration callback.
- */
-asmlinkage void smp_task_migration_interrupt(void)
-{
-	task_t *p;
-
-	ack_APIC_irq();
-	p = new_task;
-	_raw_spin_unlock(&migration_lock);
-	sched_task_migrated(p);
-}
 /*
  * this function sends a 'reschedule' IPI to another CPU.
  * it goes straight through and wastes no time serializing

fs/pipe.c

@@ -116,7 +116,7 @@ pipe_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
 		 * writers synchronously that there is more
 		 * room.
 		 */
-		wake_up_interruptible_sync(PIPE_WAIT(*inode));
+		wake_up_interruptible(PIPE_WAIT(*inode));
 		if (!PIPE_EMPTY(*inode))
 			BUG();
 		goto do_more_read;
@@ -214,7 +214,7 @@ pipe_write(struct file *filp, const char *buf, size_t count, loff_t *ppos)
 			 * is going to give up this CPU, so it doesnt have
 			 * to do idle reschedules.
 			 */
-			wake_up_interruptible_sync(PIPE_WAIT(*inode));
+			wake_up_interruptible(PIPE_WAIT(*inode));
 			PIPE_WAITING_WRITERS(*inode)++;
 			pipe_wait(inode);
 			PIPE_WAITING_WRITERS(*inode)--;

include/asm-i386/hw_irq.h

@@ -35,14 +35,13 @@
  *  into a single vector (CALL_FUNCTION_VECTOR) to save vector space.
  *  TLB, reschedule and local APIC vectors are performance-critical.
  *
- *  Vectors 0xf0-0xf9 are free (reserved for future Linux use).
+ *  Vectors 0xf0-0xfa are free (reserved for future Linux use).
  */
 #define SPURIOUS_APIC_VECTOR	0xff
 #define ERROR_APIC_VECTOR	0xfe
 #define INVALIDATE_TLB_VECTOR	0xfd
 #define RESCHEDULE_VECTOR	0xfc
-#define TASK_MIGRATION_VECTOR	0xfb
-#define CALL_FUNCTION_VECTOR	0xfa
+#define CALL_FUNCTION_VECTOR	0xfb
 
 /*
  * Local APIC timer IRQ vector is on a different priority level,

include/linux/init_task.h

@@ -52,6 +52,8 @@
     mm:			NULL,						\
     active_mm:		&init_mm,					\
     run_list:		LIST_HEAD_INIT(tsk.run_list),			\
+    migration_list:	LIST_HEAD_INIT(tsk.migration_list),		\
+    migration_sem:	__MUTEX_INITIALIZER(tsk.migration_sem),		\
     time_slice:		HZ,						\
     next_task:		&tsk,						\
     prev_task:		&tsk,						\

include/linux/sched.h

@@ -150,8 +150,7 @@ extern void update_process_times(int user);
 extern void update_one_process(struct task_struct *p, unsigned long user,
 			       unsigned long system, int cpu);
 extern void scheduler_tick(int user_tick, int system);
-extern void sched_task_migrated(struct task_struct *p);
-extern void smp_migrate_task(int cpu, task_t *task);
+extern void migration_init(void);
 extern unsigned long cache_decay_ticks;
 
 
@@ -286,6 +285,10 @@ struct task_struct {
 
 	wait_queue_head_t wait_chldexit;	/* for wait4() */
 	struct completion *vfork_done;		/* for vfork() */
+
+	list_t migration_list;
+	struct semaphore migration_sem;
+
 	unsigned long rt_priority;
 	unsigned long it_real_value, it_prof_value, it_virt_value;
 	unsigned long it_real_incr, it_prof_incr, it_virt_incr;
@@ -382,7 +385,12 @@ do { if (atomic_dec_and_test(&(tsk)->usage)) __put_task_struct(tsk); } while(0)
  */
 #define _STK_LIM	(8*1024*1024)
 
+#if CONFIG_SMP
 extern void set_cpus_allowed(task_t *p, unsigned long new_mask);
+#else
+# define set_cpus_allowed(p, new_mask) do { } while (0)
+#endif
+
 extern void set_user_nice(task_t *p, long nice);
 extern int task_prio(task_t *p);
 extern int task_nice(task_t *p);
@@ -460,7 +468,6 @@ extern unsigned long prof_len;
 extern unsigned long prof_shift;
 
 extern void FASTCALL(__wake_up(wait_queue_head_t *q, unsigned int mode, int nr));
-extern void FASTCALL(__wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr));
 extern void FASTCALL(sleep_on(wait_queue_head_t *q));
 extern long FASTCALL(sleep_on_timeout(wait_queue_head_t *q,
 				      signed long timeout));
@@ -474,13 +481,9 @@ extern void FASTCALL(sched_exit(task_t * p));
 #define wake_up(x)			__wake_up((x),TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1)
 #define wake_up_nr(x, nr)		__wake_up((x),TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr)
 #define wake_up_all(x)			__wake_up((x),TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 0)
-#define wake_up_sync(x)			__wake_up_sync((x),TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, 1)
-#define wake_up_sync_nr(x, nr)		__wake_up_sync((x),TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, nr)
 #define wake_up_interruptible(x)	__wake_up((x),TASK_INTERRUPTIBLE, 1)
 #define wake_up_interruptible_nr(x, nr)	__wake_up((x),TASK_INTERRUPTIBLE, nr)
 #define wake_up_interruptible_all(x)	__wake_up((x),TASK_INTERRUPTIBLE, 0)
-#define wake_up_interruptible_sync(x)	__wake_up_sync((x),TASK_INTERRUPTIBLE, 1)
-#define wake_up_interruptible_sync_nr(x) __wake_up_sync((x),TASK_INTERRUPTIBLE,  nr)
 asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru);
 
 extern int in_group_p(gid_t);

init/main.c

@@ -413,7 +413,12 @@ static void __init do_initcalls(void)
  */
 static void __init do_basic_setup(void)
 {
-
+	/*
+	 * Let the per-CPU migration threads start up:
+	 */
+#if CONFIG_SMP
+	migration_init();
+#endif
 	/*
 	 * Tell the world that we're going to be the grim
 	 * reaper of innocent orphaned children.

kernel/ksyms.c

@@ -443,7 +443,6 @@ EXPORT_SYMBOL(iomem_resource);
 /* process management */
 EXPORT_SYMBOL(complete_and_exit);
 EXPORT_SYMBOL(__wake_up);
-EXPORT_SYMBOL(__wake_up_sync);
 EXPORT_SYMBOL(wake_up_process);
 EXPORT_SYMBOL(sleep_on);
 EXPORT_SYMBOL(sleep_on_timeout);
@@ -458,6 +457,9 @@ EXPORT_SYMBOL(sys_sched_yield);
 EXPORT_SYMBOL(set_user_nice);
 EXPORT_SYMBOL(task_nice);
 EXPORT_SYMBOL_GPL(idle_cpu);
+#if CONFIG_SMP
+EXPORT_SYMBOL_GPL(set_cpus_allowed);
+#endif
 EXPORT_SYMBOL(jiffies);
 EXPORT_SYMBOL(xtime);
 EXPORT_SYMBOL(do_gettimeofday);