On 2016年06月27日 22:05, Boqun Feng wrote:

On Mon, Jun 27, 2016 at 01:41:28PM -0400, Pan Xinhui wrote:

quoted

this supports to fix lock holder preempted issue which run as a guest

for kernel users, we could use bool vcpu_is_preempted(int cpu) to detech
if one vcpu is preempted or not.

The default implementation is a macrodefined by false. So compiler can
wrap it out if arch dose not support such vcpu pteempted check.

archs can implement it by define arch_vcpu_is_preempted().

Signed-off-by: Pan Xinhui <redacted>
---
  include/linux/sched.h | 9 +++++++++
  1 file changed, 9 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6e42ada..dc0a9c3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h

@@ -3293,6 +3293,15 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)

  #endif /* CONFIG_SMP */

+#ifdef arch_vcpu_is_preempted
+static inline bool vcpu_is_preempted(int cpu)
+{
+	return arch_vcpu_is_preempted(cpu);
+}
+#else
+#define vcpu_is_preempted(cpu)	false
+#endif
+

I think you are missing Peter's comment here. We can

#ifndef vcpu_is_preempted
#define vcpu_is_preempted(cpu)	fasle
#endif

And different archs implement their own versions of vcpu_is_preempted(),
IOW, no need for an arch_vcpu_is_preempted().

yes, right.
just vcpu_is_preempted, no arch_vcpu_is_preempted..
thanks

Regards,
Boqun

quoted

  extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);
  extern long sched_getaffinity(pid_t pid, struct cpumask *mask);

--
2.4.11