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    SubjectRe: [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear()
    On Wed, Jan 09, 2019 at 12:47:25PM +0100, Sebastian Andrzej Siewior wrote:
    > The preempt_disable() section was introduced in commit

    <---- newline here.

    > a10b6a16cdad8 ("x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic")

    <---- newline here.

    > 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
    > copy_init_fpstate_to_fpregs().
    > A preemption here has little meaning because the register will always be

    s/register/registers/

    > 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

    ditto.

    > 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 <bigeasy@linutronix.de>
    > ---
    > 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();
    > fpu__initialize(fpu);
    > user_fpu_begin();
    > copy_init_fpstate_to_fpregs();
    > - preempt_enable();
    > }
    > }
    >
    > --

    With the above addressed:

    Reviewed-by: Borislav Petkov <bp@suse.de>

    --
    Regards/Gruss,
    Boris.

    Good mailing practices for 400: avoid top-posting and trim the reply.

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