MIPS: Fix race condition with FPU thread task flag during context switch.

[ralf@linux-mips.org: Cosmetic changes; also fixed up r2300_switch.S and
octeon_switch.S which needed similar modifications.]

Signed-off-by: Leonid Yegoshin <yegoshin@mips.com>
Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3784/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index 9414f93..42d2a39 100644
--- a/arch/mips/kernel/r4k_switch.S
+++ b/arch/mips/kernel/r4k_switch.S
@@ -41,7 +41,7 @@
 
 /*
  * task_struct *resume(task_struct *prev, task_struct *next,
- *                     struct thread_info *next_ti)
+ *                     struct thread_info *next_ti, int usedfpu)
  */
 	.align	5
 	LEAF(resume)
@@ -53,16 +53,10 @@
 	/*
 	 * check if we need to save FPU registers
 	 */
+
+	beqz    a3, 1f
+
 	PTR_L	t3, TASK_THREAD_INFO(a0)
-	LONG_L	t0, TI_FLAGS(t3)
-	li	t1, _TIF_USEDFPU
-	and	t2, t0, t1
-	beqz	t2, 1f
-	nor	t1, zero, t1
-
-	and	t0, t0, t1
-	LONG_S	t0, TI_FLAGS(t3)
-
 	/*
 	 * clear saved user stack CU1 bit
 	 */