Messages in this thread Patch in this message | | | Date | Mon, 14 Jan 2019 19:55:06 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 03/22] x86/fpu: Remove preempt_disable() in fpu__clear() |
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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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