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SubjectRe: Deadlock in net/sunrpc/sched.c
On Thu, 2 Mar 2006, Simon Derr wrote:

> Index: linux-2.6.12.6/net/sunrpc/sched.c
> ===================================================================
> --- linux-2.6.12.6.orig/net/sunrpc/sched.c 2005-08-29 18:55:27.000000000 +0200
> +++ linux-2.6.12.6/net/sunrpc/sched.c 2006-03-02 12:41:42.000000000 +0100
> @@ -400,16 +400,16 @@ __rpc_default_timer(struct rpc_task *tas
> */
> void rpc_wake_up_task(struct rpc_task *task)
> {
> + struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
> + spin_lock_bh(&queue->lock);
> if (rpc_start_wakeup(task)) {
> if (RPC_IS_QUEUED(task)) {
> - struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
>
> - spin_lock_bh(&queue->lock);
> __rpc_do_wake_up_task(task);
> - spin_unlock_bh(&queue->lock);
> }
> rpc_finish_wakeup(task);
> }
> + spin_unlock_bh(&queue->lock);
> }

Hmm, this is just to show how to reverse the locking order.
I'm not too familiar with the rpc_tasks, and
task->u.tk_wait.rpc_waitq might not be valid.

Maybe this would be better:



--- linux-2.6.12.6.orig/net/sunrpc/sched.c 2006-03-02 13:11:51.000000000 +0100
+++ linux-2.6.12.6/net/sunrpc/sched.c 2006-03-02 13:16:19.000000000 +0100
@@ -400,15 +400,14 @@ __rpc_default_timer(struct rpc_task *tas
*/
void rpc_wake_up_task(struct rpc_task *task)
{
- if (rpc_start_wakeup(task)) {
- if (RPC_IS_QUEUED(task)) {
- struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
-
- spin_lock_bh(&queue->lock);
+ if (RPC_IS_QUEUED(task)) {
+ struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq;
+ spin_lock_bh(&queue->lock);
+ if (rpc_start_wakeup(task)) {
__rpc_do_wake_up_task(task);
- spin_unlock_bh(&queue->lock);
+ rpc_finish_wakeup(task);
}
- rpc_finish_wakeup(task);
+ spin_unlock_bh(&queue->lock);
}
}

-
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