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Subject[PATCH 2/6] x86,fpu: introduce task_disable_lazy_fpu_restore helper
Date
From: Rik van Riel <riel@redhat.com>

Currently there are a few magic assignments sprinkled through the
code that disable lazy FPU state restoring, some more effective than
others, and all equally mystifying.

It would be easier to have a helper to explicitly disable lazy
FPU state restoring for a task.

Signed-off-by: Rik van Riel <riel@redhat.com>
---
arch/x86/include/asm/fpu-internal.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index 439ac3921a1e..c1f66261ad12 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -79,6 +79,16 @@ static inline void __cpu_disable_lazy_restore(unsigned int cpu)
per_cpu(fpu_owner_task, cpu) = NULL;
}

+/*
+ * Used to indicate that the FPU state in memory is newer than the FPU
+ * state in registers, and the FPU state should be reloaded next time the
+ * task is run. Only safe on the current task, or non-running tasks.
+ */
+static inline void task_disable_lazy_fpu_restore(struct task_struct *tsk)
+{
+ tsk->thread.fpu.last_cpu = ~0;
+}
+
static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu)
{
return new == this_cpu_read_stable(fpu_owner_task) &&
--
1.9.3


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