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Date:   Wed,  9 Jan 2019 12:47:25 +0100
From:   Sebastian Andrzej Siewior <>
Cc:, Andy Lutomirski <>,
        Paolo Bonzini <>,
        Radim Krčmář <>,, "Jason A. Donenfeld" <>,
        Rik van Riel <>,
        Dave Hansen <>,
        Sebastian Andrzej Siewior <>
Subject: [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear()

The preempt_disable() section was introduced in commit
  a10b6a16cdad8 ("x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic")
and it was said to be temporary.

fpu__initialize() initializes the FPU struct to its "init" value and
then sets ->initialized to 1. The last part is the important one.
The content of the `state' does not matter because it gets set via
A preemption here has little meaning because the register will always be
set to the same content after copy_init_fpstate_to_fpregs(). A softirq
with a kernel_fpu_begin() could also force to save FPU's register after
fpu__initialize() without changing the outcome here.

Remove the preempt_disable() section in fpu__clear(), preemption here
does not hurt.

Signed-off-by: Sebastian Andrzej Siewior <>
 arch/x86/kernel/fpu/core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 1d3ae7988f7f2..1940319268aef 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -366,11 +366,9 @@ void fpu__clear(struct fpu *fpu)
 	 * Make sure fpstate is cleared and initialized.
 	if (static_cpu_has(X86_FEATURE_FPU)) {
-		preempt_disable();
-		preempt_enable();

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