rcu: Eliminate in_irq() checks in rcu_enter_nohz()

The in_irq() check in rcu_enter_nohz() is redundant because if we really
are in an interrupt, the attempt to re-enter dyntick-idle mode will invoke
rcu_needs_cpu() in any case, which will force the check for RCU callbacks.
So this commit removes the check along with the set_need_resched().

Suggested-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 7e2f297aeec86a43ad8d31d1baf8c2f8379324c5..0c6c30dc6a7cbd80e6fe7c3528d3effeee0d0cd9 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -373,13 +373,6 @@ void rcu_enter_nohz(void)
        smp_mb__after_atomic_inc();  /* Force ordering with next sojourn. */
        WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
        local_irq_restore(flags);
-
-       /* If the interrupt queued a callback, get out of dyntick mode. */
-       if (in_irq() &&
-           (__get_cpu_var(rcu_sched_data).nxtlist ||
-            __get_cpu_var(rcu_bh_data).nxtlist ||
-            rcu_preempt_needs_cpu(smp_processor_id())))
-               set_need_resched();
 }
 
 /*