sched, tile: Remove finish_arch_switch

Move the simulator bits into switch_to() and use
finish_arch_post_lock_switch() for the homecache migration bits.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/tile/include/asm/switch_to.h

@@ -53,15 +53,11 @@ extern unsigned long get_switch_to_pc(void);
  * Kernel threads can check to see if they need to migrate their
  * stack whenever they return from a context switch; for user
  * threads, we defer until they are returning to user-space.
+ * We defer homecache migration until the runqueue lock is released.
  */
-#define finish_arch_switch(prev) do {                                     \
-	if (unlikely((prev)->state == TASK_DEAD))                         \
-		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |       \
-			((prev)->pid << _SIM_CONTROL_OPERATOR_BITS));     \
-	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |             \
-		(current->pid << _SIM_CONTROL_OPERATOR_BITS));            \
+#define finish_arch_post_lock_switch() do {                               \
 	if (current->mm == NULL && !kstack_hash &&                        \
-	    current_thread_info()->homecache_cpu != smp_processor_id())   \
+	    current_thread_info()->homecache_cpu != raw_smp_processor_id()) \
 		homecache_migrate_kthread();                              \
 } while (0)
 

arch/tile/kernel/process.c

@@ -448,11 +448,24 @@ struct task_struct *__sched _switch_to(struct task_struct *prev,
 
 	/*
 	 * Switch kernel SP, PC, and callee-saved registers.
+	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
+	 * Once we return from this function we will have changed stacks
+	 * and be running with current == next.
+	 */
+	__switch_to(prev, next, next_current_ksp0(next));
+
+	/* Notify the simulator of task switch and task exit. */
+	if (unlikely(prev->state == TASK_DEAD))
+		__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_EXIT |
+			     (prev->pid << _SIM_CONTROL_OPERATOR_BITS));
+	__insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_SWITCH |
+		(next->pid << _SIM_CONTROL_OPERATOR_BITS));
+
+	/*
 	 * In the context of the new task, return the old task pointer
 	 * (i.e. the task that actually called __switch_to).
-	 * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
 	 */
-	return __switch_to(prev, next, next_current_ksp0(next));
+	return prev;
 }
 
 /*