linux-kernel - [PATCH 4.9 032/130] rcu: Remove cond_resched() from Tiny synchronize

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Date:   Tue, 24 Jan 2017 08:54:32 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH 4.9 032/130] rcu: Remove cond_resched() from Tiny synchronize_sched()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

commit f466ae66fa6a599f9a53b5f9bafea4b8cfffa7fb upstream.

It is now legal to invoke synchronize_sched() at early boot, which causes
Tiny RCU's synchronize_sched() to emit spurious splats.  This commit
therefore removes the cond_resched() from Tiny RCU's synchronize_sched().

Fixes: 8b355e3bc140 ("rcu: Drive expedited grace periods from workqueue")
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/rcu/tiny.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -185,9 +185,6 @@ static __latent_entropy void rcu_process
  * benefits of doing might_sleep() to reduce latency.)
  *
  * Cool, huh?  (Due to Josh Triplett.)
- *
- * But we want to make this a static inline later.  The cond_resched()
- * currently makes this problematic.
  */
 void synchronize_sched(void)
 {
@@ -195,7 +192,6 @@ void synchronize_sched(void)
 			 lock_is_held(&rcu_lock_map) ||
 			 lock_is_held(&rcu_sched_lock_map),
 			 "Illegal synchronize_sched() in RCU read-side critical section");
-	cond_resched();
 }
 EXPORT_SYMBOL_GPL(synchronize_sched);