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SubjectRe: [tip:core/locking 2/3] lockdep:define preallocated "stack" for BFS as per cpu variable
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On Wed, 2009-07-22 at 20:58 +0800, tom.leiming@gmail.com wrote:
> From: Ming Lei <tom.leiming@gmail.com>

This patch can use a changelog.

Why is this needed, isn't all that serialized by the graph_lock anyway?
Or are there a few paths where this isn't the case and we're now racy?

> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
> kernel/lockdep.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/lockdep.c b/kernel/lockdep.c
> index 1b1796a..1583439 100644
> --- a/kernel/lockdep.c
> +++ b/kernel/lockdep.c
> @@ -847,7 +847,7 @@ struct circular_queue {
> unsigned int front, rear;
> };
>
> -static struct circular_queue lock_cq;
> +static DEFINE_PER_CPU(struct circular_queue, lock_cq);
>
> unsigned int max_bfs_queue_depth;
>
> @@ -937,7 +937,7 @@ static int __bfs(struct lock_list *source_entry,
> {
> struct lock_list *entry;
> struct list_head *head;
> - struct circular_queue *cq = &lock_cq;
> + struct circular_queue *cq = &get_cpu_var(lock_cq);
> int ret = 1;
>
> if (match(source_entry, data)) {
> @@ -993,6 +993,7 @@ static int __bfs(struct lock_list *source_entry,
> }
> }
> exit:
> + put_cpu_var(lock_cq);
> return ret;
> }
>



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