[PATCH v2 5/5] x86, fpu: introduce try_to_restore_fpu()

[Oleg Nesterov]

Cosmetic. Every caller of restore_fpu_checking() does drop_init_fpu()
on failure, add the trivial helper and update the callers.

Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
 arch/x86/include/asm/fpu-internal.h |   15 +++++++++++----
 arch/x86/kernel/i387.c              |    8 +++-----
 arch/x86/kernel/traps.c             |    8 +++-----
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/fpu-internal.h 
b/arch/x86/include/asm/fpu-internal.h
index 4cbb40e..e71c7f5 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -384,6 +384,15 @@ static inline void drop_init_fpu(struct task_struct *tsk)
        }
 }
 
+static inline bool try_to_restore_fpu(struct task_struct *tsk)
+{
+       if (unlikely(restore_fpu_checking(tsk))) {
+               drop_init_fpu(tsk);
+               return false;
+       }
+       return true;
+}
+
 /*
  * FPU state switching for scheduling.
  *
@@ -462,10 +471,8 @@ static inline fpu_switch_t switch_fpu_prepare(struct 
task_struct *old, struct ta
  */
 static inline void switch_fpu_finish(struct task_struct *new, fpu_switch_t fpu)
 {
-       if (fpu.preload) {
-               if (unlikely(restore_fpu_checking(new)))
-                       drop_init_fpu(new);
-       }
+       if (fpu.preload)
+               try_to_restore_fpu(new);
 }
 
 /*
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index ece91cf..1918f67 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -104,12 +104,10 @@ void __kernel_fpu_end(void)
 {
        struct task_struct *me = current;
 
-       if (__thread_has_fpu(me)) {
-               if (WARN_ON(restore_fpu_checking(me)))
-                       drop_init_fpu(me);
-       } else if (!use_eager_fpu()) {
+       if (__thread_has_fpu(me))
+               WARN_ON(!try_to_restore_fpu(me));
+       else if (!use_eager_fpu())
                stts();
-       }
 
        this_cpu_write(in_kernel_fpu, false);
 }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index c632843..f516cf1 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -670,12 +670,10 @@ void math_state_restore(void)
        /* Avoid __kernel_fpu_begin() right after __thread_fpu_begin() */
        kernel_fpu_disable();
        __thread_fpu_begin(tsk);
-       if (unlikely(restore_fpu_checking(tsk))) {
-               drop_init_fpu(tsk);
-               force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
-       } else {
+       if (likely(try_to_restore_fpu(tsk)))
                tsk->thread.fpu_counter++;
-       }
+       else
+               force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
        kernel_fpu_enable();
 }
 EXPORT_SYMBOL_GPL(math_state_restore);
-- 
1.5.5.1

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