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    Subject[PATCH 3/5] x86/fpu: Fold fpu_copy into fpu__copy
    Date
    Splitting it into two functions needlessly obfuscated the code.
    While we're at it, improve the comment slightly.

    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    ---
    arch/x86/kernel/fpu/core.c | 32 +++++++++++---------------------
    1 file changed, 11 insertions(+), 21 deletions(-)

    diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
    index 7a9244df33e2..299b58bb975b 100644
    --- a/arch/x86/kernel/fpu/core.c
    +++ b/arch/x86/kernel/fpu/core.c
    @@ -231,14 +231,15 @@ void fpstate_init(union fpregs_state *state)
    }
    EXPORT_SYMBOL_GPL(fpstate_init);

    -/*
    - * Copy the current task's FPU state to a new task's FPU context.
    - *
    - * In both the 'eager' and the 'lazy' case we save hardware registers
    - * directly to the destination buffer.
    - */
    -static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    +int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    {
    + dst_fpu->counter = 0;
    + dst_fpu->fpregs_active = 0;
    + dst_fpu->last_cpu = -1;
    +
    + if (!src_fpu->fpstate_active || !cpu_has_fpu)
    + return 0;
    +
    WARN_ON_FPU(src_fpu != &current->thread.fpu);

    /*
    @@ -251,10 +252,9 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    /*
    * Save current FPU registers directly into the child
    * FPU context, without any memory-to-memory copying.
    - *
    - * If the FPU context got destroyed in the process (FNSAVE
    - * done on old CPUs) then copy it back into the source
    - * context and mark the current task for lazy restore.
    + * In lazy mode, if the FPU context isn't loaded into
    + * fpregs, CR0.TS will be set and do_device_not_available
    + * will load the FPU context.
    *
    * We have to do all this with preemption disabled,
    * mostly because of the FNSAVE case, because in that
    @@ -274,16 +274,6 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    fpregs_deactivate(src_fpu);
    }
    preempt_enable();
    -}
    -
    -int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    -{
    - dst_fpu->counter = 0;
    - dst_fpu->fpregs_active = 0;
    - dst_fpu->last_cpu = -1;
    -
    - if (src_fpu->fpstate_active && cpu_has_fpu)
    - fpu_copy(dst_fpu, src_fpu);

    return 0;
    }
    --
    2.5.0
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