x86/fpu: Use task_disable_lazy_fpu_restore() helper

Replace magic assignments of fpu.last_cpu = ~0 with more explicit
task_disable_lazy_fpu_restore() calls.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1423252925-14451-8-git-send-email-riel@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>

arch/x86/include/asm/fpu-internal.h

@@ -439,7 +439,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
 
 	if (__thread_has_fpu(old)) {
 		if (!__save_init_fpu(old))
-			old->thread.fpu.last_cpu = ~0;
+			task_disable_lazy_fpu_restore(old);
 		else
 			old->thread.fpu.last_cpu = cpu;
 
@@ -455,7 +455,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta
 			stts();
 	} else {
 		old->thread.fpu_counter = 0;
-		old->thread.fpu.last_cpu = ~0;
+		task_disable_lazy_fpu_restore(old);
 		if (fpu.preload) {
 			new->thread.fpu_counter++;
 			if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))

arch/x86/kernel/i387.c

@@ -236,7 +236,7 @@ int init_fpu(struct task_struct *tsk)
 	if (tsk_used_math(tsk)) {
 		if (cpu_has_fpu && tsk == current)
 			unlazy_fpu(tsk);
-		tsk->thread.fpu.last_cpu = ~0;
+		task_disable_lazy_fpu_restore(tsk);
 		return 0;
 	}
 

arch/x86/kernel/process.c

@@ -68,8 +68,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 
 	dst->thread.fpu_counter = 0;
 	dst->thread.fpu.has_fpu = 0;
-	dst->thread.fpu.last_cpu = ~0;
 	dst->thread.fpu.state = NULL;
+	task_disable_lazy_fpu_restore(dst);
 	if (tsk_used_math(src)) {
 		int err = fpu_alloc(&dst->thread.fpu);
 		if (err)