linux-kernel - [PATCH 5/5] RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc

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Message-ID: <20090415183501.11029.81607.stgit@warthog.procyon.org.uk>
Date:	Wed, 15 Apr 2009 19:35:01 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>,
	Dipankar Sarma <dipankar@...ibm.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH 5/5] RCU: Don't try and predeclare inline funcs as it upsets
	some versions of gcc

Don't try and predeclare inline funcs like this:

	static inline void wait_migrated_callbacks(void)
	...
	static void _rcu_barrier(enum rcu_barrier type)
	{
		...
		wait_migrated_callbacks();
	}
	...
	static inline void wait_migrated_callbacks(void)
	{
		wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
	}

as it upsets some versions of gcc under some circumstances:

	kernel/rcupdate.c: In function `_rcu_barrier':
	kernel/rcupdate.c:125: sorry, unimplemented: inlining failed in call to 'wait_migrated_callbacks': function body not available
	kernel/rcupdate.c:152: sorry, unimplemented: called from here

This can be dealt with by simply putting the static variables (rcu_migrate_*)
at the top, and moving the implementation of the function up so that it
replaces its forward declaration.

Signed-off-by: David Howells <dhowells@...hat.com>
Cc: Dipankar Sarma <dipankar@...ibm.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---

 kernel/rcupdate.c |   18 ++++++++----------
 1 files changed, 8 insertions(+), 10 deletions(-)


diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 2c7b845..a967c9f 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -58,6 +58,10 @@ static DEFINE_MUTEX(rcu_barrier_mutex);
 static struct completion rcu_barrier_completion;
 int rcu_scheduler_active __read_mostly;
 
+static atomic_t rcu_migrate_type_count = ATOMIC_INIT(0);
+static struct rcu_head rcu_migrate_head[3];
+static DECLARE_WAIT_QUEUE_HEAD(rcu_migrate_wq);
+
 /*
  * Awaken the corresponding synchronize_rcu() instance now that a
  * grace period has elapsed.
@@ -122,7 +126,10 @@ static void rcu_barrier_func(void *type)
 	}
 }
 
-static inline void wait_migrated_callbacks(void);
+static inline void wait_migrated_callbacks(void)
+{
+	wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
+}
 
 /*
  * Orchestrate the specified type of RCU barrier, waiting for all
@@ -179,21 +186,12 @@ void rcu_barrier_sched(void)
 }
 EXPORT_SYMBOL_GPL(rcu_barrier_sched);
 
-static atomic_t rcu_migrate_type_count = ATOMIC_INIT(0);
-static struct rcu_head rcu_migrate_head[3];
-static DECLARE_WAIT_QUEUE_HEAD(rcu_migrate_wq);
-
 static void rcu_migrate_callback(struct rcu_head *notused)
 {
 	if (atomic_dec_and_test(&rcu_migrate_type_count))
 		wake_up(&rcu_migrate_wq);
 }
 
-static inline void wait_migrated_callbacks(void)
-{
-	wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
-}
-
 static int __cpuinit rcu_barrier_cpu_hotplug(struct notifier_block *self,
 		unsigned long action, void *hcpu)
 {

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