rcu: Remove cond_resched() from Tiny synchronize_sched()

paulmck · paulmck · commit f466ae66fa6a · 2017-01-14T21:22:20.000-08:00
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: 8b355e3 ("rcu: Drive expedited grace periods from workqueue") Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> # 4.9.0-
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
@@ -185,17 +185,13 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
  * 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)
 {
 	RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) ||
 			 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);
 

Original file line number	Diff line number	Diff line change
`@@ -185,17 +185,13 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused`
`185`	`185`	`* benefits of doing might_sleep() to reduce latency.)`
`186`	`186`	`*`
`187`	`187`	`* Cool, huh? (Due to Josh Triplett.)`
`188`		`- *`
`189`		`- * But we want to make this a static inline later. The cond_resched()`
`190`		`- * currently makes this problematic.`
`191`	`188`	`*/`
`192`	`189`	`void synchronize_sched(void)`
`193`	`190`	`{`
`194`	`191`	`RCU_LOCKDEP_WARN(lock_is_held(&rcu_bh_lock_map) \|\|`
`195`	`192`	`lock_is_held(&rcu_lock_map) \|\|`
`196`	`193`	`lock_is_held(&rcu_sched_lock_map),`
`197`	`194`	`"Illegal synchronize_sched() in RCU read-side critical section");`
`198`		`- cond_resched();`
`199`	`195`	`}`
`200`	`196`	`EXPORT_SYMBOL_GPL(synchronize_sched);`
`201`	`197`