x86/entry: Split out idtentry_exit_cond_resched()

The XEN PV hypercall requires the ability of conditional rescheduling when
preemption is disabled because some hypercalls take ages.

Split out the rescheduling code from idtentry_exit_cond_rcu() so it can
be reused for that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202117.962199649@linutronix.de

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 2a80e4e..066215a 100644 (file)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -583,6 +583,20 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs)
        return false;
 }
 
+static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched)
+{
+       if (may_sched && !preempt_count()) {
+               /* Sanity check RCU and thread stack */
+               rcu_irq_exit_check_preempt();
+               if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
+                       WARN_ON_ONCE(!on_thread_stack());
+               if (need_resched())
+                       preempt_schedule_irq();
+       }
+       /* Covers both tracing and lockdep */
+       trace_hardirqs_on();
+}
+
 /**
  * idtentry_exit_cond_rcu - Handle return from exception with conditional RCU
  *                         handling
@@ -624,21 +638,7 @@ void noinstr idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit)
                }
 
                instrumentation_begin();
-
-               /* Check kernel preemption, if enabled */
-               if (IS_ENABLED(CONFIG_PREEMPTION)) {
-                       if (!preempt_count()) {
-                               /* Sanity check RCU and thread stack */
-                               rcu_irq_exit_check_preempt();
-                               if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
-                                       WARN_ON_ONCE(!on_thread_stack());
-                               if (need_resched())
-                                       preempt_schedule_irq();
-                       }
-               }
-               /* Covers both tracing and lockdep */
-               trace_hardirqs_on();
-
+               idtentry_exit_cond_resched(regs, IS_ENABLED(CONFIG_PREEMPTION));
                instrumentation_end();
        } else {
                /*