From 9f47015530b731cdc3dac128aa0169eb5e437fc9 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 27 Oct 2020 11:09:50 +0100 Subject: [PATCH 154/323] x86/fpu: Simplify fpregs_[un]lock() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.215-rt107.tar.xz There is no point in disabling preemption and then disabling bottom halfs. Just disabling bottom halfs is sufficient as it implicitly disables preemption on !RT kernels. Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201027101349.455380473@linutronix.de Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/include/asm/fpu/api.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index 8b9bfaad6e662..5174c0a640ef3 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -40,17 +40,18 @@ static inline void kernel_fpu_begin(void) * A context switch will (and softirq might) save CPU's FPU registers to * fpu->state and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in * a random state. + * + * local_bh_disable() protects against both preemption and soft interrupts + * on !RT kernels. */ static inline void fpregs_lock(void) { - preempt_disable(); local_bh_disable(); } static inline void fpregs_unlock(void) { local_bh_enable(); - preempt_enable(); } #ifdef CONFIG_X86_DEBUG_FPU -- 2.44.0