Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation"
This reverts commit 616c310e83b872024271c915c1b9ab505b9efad9.
(Move PREEMPT_RCU preemption to switch_to() invocation).
Testing by Sasha Levin <levinsasha928@gmail.com> showed that this
can result in deadlock due to invoking the scheduler when one of
the runqueue locks is held. Because this commit was simply a
performance optimization, revert it.
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 854dc4c..4e56a9c 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -87,6 +87,10 @@
#ifdef CONFIG_TINY_RCU
+static inline void rcu_preempt_note_context_switch(void)
+{
+}
+
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
{
*delta_jiffies = ULONG_MAX;
@@ -95,6 +99,7 @@
#else /* #ifdef CONFIG_TINY_RCU */
+void rcu_preempt_note_context_switch(void);
int rcu_preempt_needs_cpu(void);
static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
@@ -108,6 +113,7 @@
static inline void rcu_note_context_switch(int cpu)
{
rcu_sched_qs(cpu);
+ rcu_preempt_note_context_switch();
}
/*