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>

1 files changed, 3 insertions, 9 deletions

diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S
index 9414f9354469..42d2a3938420 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
          */
-        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)
+        beqz    a3, 1f
 
+        PTR_L   t3, TASK_THREAD_INFO(a0)
         /*
          * clear saved user stack CU1 bit
          */