switch_fpu_prepare() calls use_eager_fpu() 3 times, and every call
is confusing.
1st: "tsk_used_math(new) && use_eager_fpu()" is pointless, eagerfpu
means that used_math() is also true.
2nd: !fpu.preload && use_eager_fpu() is not possible, we do not need
to check use_eager_fpu() before use_eager_fpu(). IOW, !preload
alway means !use_eager_fpu(), so this check only adds more
confusion.
3rd: If __thread_has_fpu(old) == F then use_eager_fpu() is false too,
no need to check it before fpu_lazy_restore(). IOW, the "else"
branch is simply impossible if use_eager_fpu().
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
arch/x86/include/asm/fpu-internal.h | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/fpu-internal.h
b/arch/x86/include/asm/fpu-internal.h
index ae6bd35..7b95a87 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -424,8 +424,8 @@ static inline fpu_switch_t switch_fpu_prepare(struct
task_struct *old, struct ta
* If the task has used the math, pre-load the FPU on xsave processors
* or if the past 5 consecutive context-switches used math.
*/
- fpu.preload = tsk_used_math(new) && (use_eager_fpu() ||
- new->thread.fpu_counter > 5);
+ fpu.preload = use_eager_fpu() ||
+ (tsk_used_math(new) && new->thread.fpu_counter > 5);
if (__thread_has_fpu(old)) {
if (!__save_init_fpu(old))
cpu = ~0;
@@ -437,14 +437,14 @@ static inline fpu_switch_t switch_fpu_prepare(struct
task_struct *old, struct ta
new->thread.fpu_counter++;
__thread_set_has_fpu(new);
prefetch(new->thread.fpu.state);
- } else if (!use_eager_fpu())
+ } else
stts();
} else {
old->thread.fpu_counter = 0;
old->thread.fpu.last_cpu = ~0;
if (fpu.preload) {
new->thread.fpu_counter++;
- if (!use_eager_fpu() && fpu_lazy_restore(new, cpu))
+ if (fpu_lazy_restore(new, cpu))
fpu.preload = 0;
else
prefetch(new->thread.fpu.state);
--
1.5.5.1
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