On Sun, 2010-09-19 at 15:09 +0200, Avi Kivity wrote: > Some time ago, the i8259 emulation code in kvm was changed to use > raw_spinlock_t, as it was called in a preempt_disable() and > local_irq_disable() context, which doesn't work with preemptible > spinlocks used with CONFIG_PREEMPT_RT. > > In Linux 2.6.37, the spinlock will no longer be taken in these contexts, > so I'd like to change it to a normal spinlock_t. However, it is still > taken in a spin_lock_irq() context. > > Is it okay to do this change? I figured since spin_lock_irq() is part > of the spinlock infrastructure it might to the right thing. > In PREEMPT_RT all interrupts (besides the timer) is converted to a thread. The spin_lock_irq() will not disable interrupts in PREEMPT_RT, because it is not needed (irqs are threaded and wont cause a deadlock if they share the same spin_locks). Note, spin_locks used by the timer will must be raw_spin_lock(), and threaded context must disable interrupts for real before using it. -- Steve -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
