x86/fpu: Simplify fpregs_[un]lock()

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 <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201027101349.455380473@linutronix.de

diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index dcd9503b1098388d415c7cdd89428090292ecf21..2c5bef78a4844eb1956d11a4f279e2de4057bc8e 100644 (file)
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -29,17 +29,18 @@ extern void fpregs_mark_activate(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