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SubjectRe: [PATCH 5/5] RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc
On Wed, Apr 15, 2009 at 07:35:01PM +0100, David Howells wrote:
> 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.

Looks good to me!

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> Signed-off-by: David Howells <dhowells@redhat.com>
> Cc: Dipankar Sarma <dipankar@in.ibm.com>
> Cc: Paul E. McKenney <paulmck@linux.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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